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1. A Appendix I Parts List PART NO PART NAME QTY MATERIAL METHOD STOCK SIZE 100 100 INNER GRIPPER 1 N A 00 103 FINGER INNER GRIPPER 3 STEEL WJ 00 105 LINK INNER GRIPPER 6 STEEL WJ 00 107 CENTER SHAFT INNER GRIPPER 1 STEEL CNC 03 16 X 3 00 108 TOP MOUNT INNER GRIPPER 1 STEEL 2 X2 X 00 109 BOTTOM MOUNT INNER GRIPPER 1 STEEL 2 2 1 25 00 110 LINK SERVO INNER GRIPPER 1 STEEL 00 111 SERVO INNER GRIPPER 1 N A N A 00 112 BRACKET SERVO MOUNT INNER GRIPPER l AL CNC 1 5 0 5 00 113 CRANK SERVO INNER GRIPPER 1 N A N A MCMASTER PN 92735 110 PIN INNER GRIPPER 12 N A N A 100 000 R2 OUTER GRIPPER 1 N A 00 001 FINGER OUTER GRIPPER 2 STEEL MANUAL 00 002 LINK OUTER GRIPPER 6 STEEL WJ 00 003 R2 MOUNTING BLOCK FINGER LINKS OUTER GRIPPER 2 AL CNC 4 X3 X2 SQUARE TUBING INNER GRIPPER HOUSING 3X3 00 004 0 125 1 AL MANUAL 00 005 LINK ESSENTRIC CRANK OUTER GRIPPER 2 STEEL WJ 00 006 LINK ACTUATOR TO ESSENTRIC CRANK 2 STEEL CNC 00 007 END CAP 3X3 SQUARE TUBING 1 AL CNC 3 X3 X 1 SQUARE TUBING ACTUATOR HOUSING 2X2 0 125 00 008 THK 1 AL MANUAL 00 009 END CAP 2X2 SQUARE TUBING GRIPPER SIDE 1 AL CNC 2 X2 xX 1 00 010 END CAP 2X2 SQUARE TUBING BOTTOM SIDE 1 AL CNC 2 X2 X 1 00 011 BRACKET 4IN ACTUATOR BASE MOUNT 1 AL 22 PA 14 4 150 ACTUATOR 4IN PROGRESSIVE AUTOMATIONS 1 N A N A PA 14 10 150 ACTUATOR 10IN
2. Channels Cost Voltage Peak Continuous Input Type USD V Current Current 2 Cytron Proprietary SaberTooth Analog PWM Serial SyRen 75 24 45 24 Analog PWM Serial Pololu Analog USB TTL PWM Simple H 1 80 24 4 25 PWM Jaguar 1 85 24 45 40 Serial Can 2 Communicating with motor controllers There are several different types of communication that can be used to talk with motor controllers Some of the more popular methods include CAN RS232 or Ethernet communication Direct forms of control one way communication include analog voltage and PWM signals CANBUS CAN communication consists of a series of ranked nodes Each node contains a processor a CAN protocol controller with a synchronous clock and an actual transceiver Nodes can send and receive messages independently from each other using a Non Return To Zero protocol which means that the voltages range from 5V to 5V never using asa communications signal to prevent errant signals processing 23 Node Node Len MOOR ID Byte o Byte 1 Byte Bytes 6 Byte 7 Figure 20 CANBUS 23 The messages are sent in packets with the node ID and other address information If two nodes are talking at the same time the node with the higher ranking resumes with priority Speeds for this application on a robot can reach one megabit per second of digital information RS232 F
3. gt 30 20 10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 Distance yards Figure 50 Link quality and strength as a function of distance from controller E Cost Analysis A cost analysis was performed as cost was a key factor contributing to the marketability and widespread availability of the robot The total amount of money spent in the development of the robot prototype was 2 998 19 USD This figure does not represent the hardware that was donated including two Axis cameras totaling 1 918 00 USD as shown in Table 8 a wheelchair base from The Wheelchair Recycler which was used as a mobile base platform and the National Instruments sbRIO board 72 Table 8 Axis Camera Donation Qty Product Axis Part MSRP 1 212 0257 004 649 00 1 214 0246 004 1 299 00 A production ready robot would have the added cost of the cameras onboard controller and a base platform however many of the features used in the prototype are far more powerful then are needed in a production model Assuming the MSRP for all components on the robot the final cost still totals only about 7 000 00 USD well below the 10 000 goal 73 VIII Recommendations for future development There are a number of possible developments that can be made to improve the robot in future years including weight reduction of the mechanical systems developing a custom base
4. 85 Wrist CW Limit Input Port5 DIOO 21 30 Wrist CCW Limit Power Port6 DIOO 23 31 Wrist CCW Limit Input Port6 DIOO 25 Port6 DIOO 27 Port6 DIOO 29 Port6 DIOO 31 Port6 DIOO 33 Port6 DIOO 35 Digital Out Pin Port Pin of Destination Connector Disruptor Signal Port0 DIO4 11 Disruptor Relay 1 Disruptor Ground D GND 12 Disruptor Relay Spotlight 1 Signal PortO0 DIOS 13 Spotlight 1 Relay 2 Spotlight 1 Ground D GND 14 Spotlight 1 Relay Spotlight 2 Signal Port0 DIO6 15 Spotlight 2 Relay 3 Spotlight 2 Ground D GND 16 Spotlight 2 Relay To Be Assigned Signal Port0 DIO7 17 TBD 4 To Be Assigned Ground D GND 18 TBD Digital Input Descriptions are from facing the front of the robot 86 C Appendix III Packet Overview S Total Types of packets Packets TO sbRIO FROM host GET Packet Requests data from the robot 1 or more sensors MOVE Packet Sets 1 or more PWM s on the robot SET Packet Changes 1 or more relays on the robot SAFE Packet Shutdown the arm base or entire robot Safety stop Packets FROM sbRIO TO host e RETURN Packet Returns requested sensor data Packet Details GET Packet This packet is sent from the host to obtain sensor data from the sbRIO Packet Structure SOURCE 1B SOURCE CONTROL 1 when requesting data ACTION 1B GET 71 decimal for G NUMBER OF DEVICES 1B The n
5. E A 9 E B amp gt amp d o 2 ob S g 5 E S 5 2 gt 2 am Las _ Andros HD 1 Remotec 4 3 3 21 6603 1 MURV 100 MURV 100 6 w ue Del DR pepe EE RMI 10F RMEIOF 2 Pedsco E l peg Scarab IIA EL 6 5 Eg 23 _ e ww pwosovus ims er w 2s mus s x Network Communication Methods From every aspect of the operator s controller unit to every sensor and actuator on the robot itself without a means of communicating between the user interface and the robot the entire system would be useless There are many different ways to link a control system to a device when the two can t reside on the same physical piece of equipment because they will be moving independently from each other Types of common controllers one might use frequently such as a television remote or radio controlled toy car typically have no feedback so the controller only needs to be able to transmit a signal and the device receive it as opposed to both ends using transceivers Two other important aspects of the communication system are the 15 reliability of the connection and the amount of available throughput to ensure there s enough bandwidth for supporting multiple simultaneous video feeds A mini
6. and lowering the production costs Reducing the weight of the robot would greatly increase its usability This would allow for the robot to be more easily loaded into a vehicle and transported by smaller teams Additionally reducing the weight of the arm would allow the robot to lift a larger payload One method to approach this would be to explore the use of hydraulic systems which have a higher power to weight ratio then electric actuators Hydraulic systems would have additional advantages such as energy regeneration capabilities and decreased size For this prototype a wheelchair base was used due to the scope of the project limiting the time to produce a custom base The addition of a custom base could allow for off road capabilities to be improved and the potential for stair climbing while greatly reducing the robot weight The custom base could use tracks or outrigger paddles to allow for greater stability and the ability to cover more terrain The donated equipment such as the AXIS cameras and the NI sbRIO are ideal for the development of a new system due to their flexibility and high capabilities A production model would not need the same capabilities as the prototype New hardware components could be found that would decrease the production cost for higher volume production This project concentrated on developing a gripper that allows for the removal of blasting caps however it would improve the capabilities of the robot to i
7. o vem bn Itu nt nba M i Fable of a ette pee bra dotate dece onec env de P abe td Bomb Disposal Robot Prot t p iere ren terni bee tut ibo 1 L UPA UIC ONE ca ace 2 4 AD E 4 Sensor Feedback testes 6 Controls and 6 D Mechanical Systems ose desea ua dete ts dead 9 E Network Communication Methods eee teta entree eei der 15 F Hardware Components QD A 18 Motor COTO CTS UA tO IR Mm a 18 2 Communicating with motor controllers 000 23 3 Robot Controller c ee teet oO tv Sid ius 25 42 ncc pM PEE 28 EM eru 31 viU 8 MCCC 32 MI Methodology d baba que adc a ORE e d ba
8. 14 15 16 17 18 19 20 21 22 23 24 25 26 Higher Speed Study Group LMSC LAN MAN Standards Committee Project 802 IEEE 30 NOV 2007 WEB 26 Apr 2011 lt http www ieee802 org 3 hssg gt Hornback P 1998 The Wheel versus Track Dilemma Armor 33 34 How to Choose the Transistor and the Current Limiting Resistor of the H bridge Let s Make Robots Let s Make Robots Let s Make Robots Web 21 Apr 2011 lt http letsmakerobots com node 4767 gt ICOR Technology CALIBER T5 Small EOD SWAT Robot Ottawa ON Online IEEE 802 3 Protocol Rigacci org rigacci org Web 21 Apr 2011 lt http www rigacci org docs biblio online intro_to_networking c4642 htm gt IEEE 802 1 1n 2009 Amendment 5 Enhancements for Higher Throughput IEEE SA 29 October 2009 lt http dx doi org 10 1109 2FIEEESTD 2009 5307322 gt IFI Robotics FRC Robot Controller IFI Robotics The Art and Science of Control IFI Robotics Web 26 Apr 2011 lt http www ifrobotics com rc shtml gt Introduction to Pulse Width Modulation PWM O Reilly Media O Reilly Media Technology Books Tech Conferences IT Courses News Web 21 Apr 2011 lt http www oreillynet com pub a network synd 2003 07 02 pwm html gt iRobot iRobot 510 Packbot Bedford MA Online Keller John Navy to Continue Buys of Bomb disposal Unmanned Ground Vehicles UGVs from IRobot in 23
9. give the primary perspective of objects being picked up moved or pulled apart E Control Hardware The robot has a stand alone control system equipped to run all the motors actuators and sensors as well as actively monitor the conditions of the robot Essential hardware components of the robot are depicted in Figure 34 each of which are described in detail throughout the Mechanical and Hardware Design section The onboard control operation is run by a National Instruments single board RIO model 9612 sbRIO The controller is responsible for sending out the PWM signals required to control the motors This small but powerful board is also capable of processing the signals from the robot s sensor suite as described above The sensor suit also includes three onboard cameras providing visual feedback to the user Each camera provides a unique view of the robot to provide as much situational awareness as possible These cameras along with the sbRIO communicate with the onboard network router system with network packets from the wirelessly transmitted user input 43 gt Wheelchair and Arm Drive Motors Drive Motor Controllers On board sbRIO Actuator Motor Controllers Y 7 dBi Directional Wireless Router Antenna with 9 3 dBi ecce ua TUN Omni x i Directional DE c T m Fa 4 Gripper Actuators ad Potentiometers Limit Switches Pressure Sensors Ultrasonic lt P IR Range Finders
10. Novel EOD Robot Design with Dexterous Gripper and Intuitive Teleoperation A Major Qualifying Project submitted to the faculty of Worcester Polytechnic Institute in partial fulfillment of the requirements for the Degree of Bachelor of Science Submitted by Matthew W Carey RBE ECE Eric M Kurz RBE Joshua D Matte ME Timothy D Perrault RBE Advised by Professor Taskin Padir Advisor Code Project Code 1 April 22 2011 Abstract This paper details the design and implementation of an intelligent explosive ordinance disposal EOD robot to provide law enforcement agencies with a cost effective and reliable robotic platform The key features of the robot include an intuitive user interface which provides additional sensor feedback and enhanced visual awareness compared to existing systems an onboard three degree of freedom manipulator arm providing an enlarged workspace and a dexterous gripper allowing for the removal of detonators The flexible and modular robot design utilizes commercial off the shelf components for ease of maintenance and repairs The robot provides a safe distance threat assessment and increased capacity for explosive ordinance disposal improving the effectiveness of bomb disposal teams The robot s low cost intuitive operation and ease of maintenance promote its widespread appeal thereby saving the lives of both law enforcement personnel and civilians Contents
11. the USB transceiver 15 designed to be able to run at up to 1000 mW 30 dBm There was a concern that if the robot was using 802 11 wireless networking there would be too much interference in the 2 4 GHz spectrum in which it operates Typically a user is presented with the choice to run their wireless network on a channel numbered one through eleven which correspond to the frequencies ranging from 2 412 GHz to 2 462 GHz a 50 MHz block What most don t realize is that while these channels are equally spaced out 5 MHz apart from each other even at 100 dBm 802 11 is typically considered to be non operational below 85 dBm due to a high rate of packet loss each channel requires 22 MHz of bandwidth This means that only three channels one six or eleven can be used without overlapping and causing or receiving interference from another channel as seen in Figure 36 Another benefit of the non default firmware on the router is the benefit to set a channel of 12 13 or 14 Since channel 14 15 specifically not allowed for use by the FCC in the USA broadcasting a relatively high power wireless network on the frequency wasn t desirable The next best choice to have the least amount of interference possible when already surrounded in the worst case scenario with networks on channels one through eleven is channel 13 which has a bandwidth block centered around one endpoint for channel eleven This means that there will be interference but the amplifie
12. APPR enam OUTER GRIPPER CONFIDENTIAL TOUSTANCING PEE COMMENTS CF SIZE DWG NO COMPANY ANY ENEAN E EASA MIAE emu wn 100 002 ees APPUCATION DO NOI SCALE DRAWING SCALE 122 WEIGHT SHEET 1 OF 1 5 4 3 2 1 90 UNLESS OTHERWISE SPECIRED DIMENSIONS ARE IN INCHES DRAWN CHECKED ENG APPR THREE PLACE DECIMAL MFG APPR MAPAS ALUMINUM MAM ANY assy COMPANY DO NOI SCALE DRAWING 5 4 3 000 M 3 000 125 4X 250 THRU ALL E 1 125 i __ 2X 0194 THRU ALL 1 750 UNLESS OTHERWISE SPECIFIED DIMENSIONS ARE IN INCHES DRAWN TWORACEDECMAL 108 THREE PLACE DECIMAL MEO AFER ei CONTAINED MATERAL DRAWING I5 TH SOLE PROPERTY CF COMPANY neat assy WED ON COMPANY 47 DO SCALE DRAWING 1 875 125 CHAMFER MOUNTING BLOCK FINGER LINKS OUTEER GRIPPER SZE DWG NO REV A 100 003 R2 SCALE 1 2 WEIGHT SHEET 1 OF 1 SQUARE TUBING INNER GRIPPER HOUSING 3X3 0 125 THK SUE DWG NO A 100 004 SCALE 1 5 WEIGHT SHEET 1 OF 1 9 jr 1050 CHAMFER gt 3625 THRU ALL UNLESS OTHERWISE NAME DATE DIMENSIONS ARE IN INCHES DRAWN CHECKED ANQUAR MACH 80002 APPR THREE PLA
13. Controller Figure 34 Hardware systems overview F Controller A standard control device is implemented to reduce complexity and long learning curves for operators The Xbox 360 gamepad was selected since many younger operators are already fairly familiar with it This intuitive standard controller that comfortably fits in one s hands allows utilization of up to five analog axes and ten digital buttons A breakdown of the control scheme is shown in Figure 38 By using this gamepad instead of some far more complex controllers the learning curve for a new operator will be significantly decreased due to inherent familiarity 44 V Design of Software and Communication Systems A Network Communication In order to communicate with the mobile robot remotely and meet the communications range and throughput specifications a wireless router is installed on the mobile base The IEEE 802 11 architecture used here is often found implemented in homes and businesses using integrated antennas and off the shelf routers or access points APs limiting the communication distance to approximately 40 meters By choosing an appropriate protocol version and amplifying the two transceivers both in software and physically with antennas the specification which required full usage at a minimum of 150 meters was met and exceeded with ease To determine the best 802 11 protocol version the requirements of a wireless network need to be taken into consideratio
14. R398 777 0 25 E E oon m EUN unu ACTUATOR NOSE Prn MOUNT BRACKET s ne sou recreen cr i ALUMINUM SIZE DWG NO noe MeN DONOTSCALEDRAWNG SCALE 21 WEGHT SHEET 1 OF 1 5 4 3 2 1 438 Thi Q 250 N 1 500 Roy ss 1 4 20 Tapped Hole 4 0 2x 8125 250 L Hi I me 1 350 1 1 500 mE ACTUATOR NOSE WAEPACEDRCMAL 1 MOUNT BRACKET quem INNER GRIPPER mur ERA SIZE DWG NO n 100 015 APPUCATION NOT SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 2 1 94 m TE FINGER Q INNER GRIPPER SUE DWG NO amos A 100 103 APPUCATION DO NOI SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 3 2 1 2X R 125 Es 125 2 125 __ THRU ALL EN 025 CHAMFER os o mE 8 LINK INNER GRIPPER LLL rim 7 100 105 meno eem t HPRICATOR DO NOTSCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 2 1 95 5 188 2 500 Tq 1 4 20 THREADS ON BOTTOM END MATES WITH 100 015 UNLESS OTHERWISE SPECIFED NAME DATE DIMENSIONS ARE IN INCHES DRAWN CHECKED TLE Ex ao moame CENTER SHAFT INNER GRIPPER Er 100 107 APPLICATION DO NOT SCALE DRAWING SCALE 1 1 WEIGHT
15. Safety System i a tod Osa e Ui Mp be qr TR ad 49 Cascaded PID Arm Control System nete ete eren teuer 51 Labview programming dose ene oa pada do ubi Po etin e 52 Gamepad Control Pin OoHt ui trie rite pbi aei 54 Graphical User Interface 1 1 56 ED RIAL LOM a ee EE eu 60 Oscillation motion PID Simulation 61 Linearization for Dynamic Model of Robot Arm 62 Cascaded Control LOO iue ade iet nere er de tine orta dete y obe even 63 Saturated Velocity Controller eie d tareas rg eq 63 Cascaded PID Slew Rate Added 65 ENS UT OUS DERI 69 Side WIC Wi E 69 Link quality and strength as a function of distance from controller 72 vi Table of Tables Table 1 Gripper Claw Comparison sodas tn t Queen aid tato 10 Table 2 Comparison of key features of competitive EOD robots Values dependent on accessories installed iu unice cuir dass RR Ia eue 15 Table 3 Motor Controller Summary eno Pen bane ean een 23 Table d Drive red he S ipe
16. 3 3 0 seconds 9 1 seconds Test 4 2 9 seconds 9 1 seconds Average Average 2 93 seconds Average 9 13 seconds One of the task specifications was that the robot must be able to attain a top speed of four miles per hour The speed was tested on a football field where distance was accurately measured every yard The first test measured the rate of acceleration Across four tests from completely stopped to the five yard line the average time was 2 93s as seen in Table 6 Acceleration and 40 Maximum Speed Testing Results This means in the first five yards the robot attained a velocity of 3 5 miles per hour Further testing was performed at 10 and 30 yards to measure the maximum velocity In four tests performed with nearly fully charged batteries there was no more than 1 deviation from the average for the 30 yard dash test results displayed in Table 6 Acceleration and Maximum Speed Testing Results The ten yard timings were used to confirm that they were one third of the 30 yard timings meaning that the robot had indeed achieved full speed by the time it started the test The resulting maximum speed is 9 1 seconds to travel 30 yards or 3 3 yards per second In miles per hour this correlates to 6 75 mph well above the four mile per hour goal D Sensor Suite The robot sensor suite includes a range of sensors providing position feedback at all of the arm joints pressure feedback and range finders on the gripper
17. D Iteration 3 Position and Velocity 1 62 E Iteration 4 Position and Velocity Control with slew rate 4 4 222222 64 VH e Y 66 A Finished Robot Sec ICAL ONS osea Oe oth oce at Ree n Ad S e et 66 B Mechanical Systems a d direi pae pe esse A 69 C Interface e MM M LIA DEALS 70 D Mareless Capabilities 71 iii VIII IX XI XIII XIV mo Oo gt Cost AMAL Y eT T IEEE 72 Recommendations for future development sse 74 Greater Impacts uere sue trei RR D Me PON i Vd 75 OTIC LS OTIS M E 76 Acknowledgementsra e te xD ee t E 76 77 APPENDICES Gs 80 Appendix I Parts T 80 Appendix I Electrical Pin out for SDRIO eR S Na edi 82 Appendix Packet Overview eic aie e nio eile eterne te tun dee aen dein 87 Appendix IV Mechanical Drawings of Key Components esses 90 Appendix Vs Dser 102 iv Table of Figures Eioure aries eodd du til
18. Photography by Thomas Knoblauch Web 21 2011 lt http www star shine ch astro autostar autostar LX200 LXD75 html gt Axis Products Axis Communications Leader in Network Cameras and Other IP Networking Solutions Web 26 Apr 2011 lt http www axis com gt Axon II Microcontroller Trossen Robotics World s Leading Robot Shop for Robot Kits and Robot Parts TRossen Robotics Web 26 Apr 2011 lt http www trossenrobotics com p axon I microcontroller aspx gt Blasting Cap Encyclopaedia Britannica Encyclopaedia Britannica Online Encyclopaedia Britannica 2011 Web lt http www britannica com EBchecked topic 69053 blasting cap gt Cytron 15A 6 24V Brushed DC Motor Controller IFC Series RobotShop Robot Store Robots Robot Parts Robot Kits Robot Toys Web 21 Apr 2011 http www robotshop com cytron 152a 6 24v brushed dc motor controller html utm_source google gt Defenders Network Inc MURV 100 Robot System Thibodaux Louisiana Online Dimension Engineering Sabertooth 2X10 SKU 50110 HVW Technologies HVW Technologies Microcontrollers Embedded Software Development Tools and Robotics Web 21 Apr 2011 lt http www hvwtech com products_view asp ProductID 979 gt EODPartner MR 5 Explosive amp Ordnance Disposal Robot St Johann Germany Online Flickenger Rob Wireless Networking in the Developing World Vol 2 Hacker Friendly LLC 2007 Print 77 13
19. SHEET 1 OF 1 22 TRUE R 031 THRU ALL 108 DIMENSIONS ARE IN INCHES qn TOP MOUNT INNER GRIPPER Saas A 100 108 meno NOTSCALE DRAWING SCALE 2 1 WEIGHT SHEET 1 OF 1 5 4 2 1 96 __ 188 THRUALL 3X 6 125 THRU ALL 156 CHECKED bL BOTTOM MOUNT A 100 109 4X R 100 __ 2X Q 094 mn 188 pi wos ome m BRACKET SERVO MOUNT wee INNER GRIPPER peues ne seroren ce MABE ALUMINUM SIZE DWG NO 100 112 DO NOT SCALE DRAWING SCALE 2 1 WEIGHT SHEET 1 OF 1 97 ae 8 TE ENG APPR GRIPPER MOUNTING THREE PLACE DECIMAL t APER BLOCK BEARING MOUNT 1 11 IS hE SOLE PROPERTY CF ALUMINUM lo 5 Snes P 100 201 oe APPUCATION DO NOT SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 3 2 1 500 NUT SHOWN 250 NOT TO MACHINED 250 i 52 000 A SHOWN i DO NOT MACHINE S E 250 THREAD 875 ROD 4X 194 __ THRU ALL _ 375 77 THRU ALL FRACTIONAI CHECKED LI ARM MOUNTING BLOCK RUNS RS BEARING MOUNT o WRIST MO
20. amount of bandwidth required from its lack of compression On the contrary MPEG4 has the benefit of providing decent compression without requiring many resources on the receiving end to decode the video but it is primarily only for sub megapixel resolutions H 264 requires significantly more CPU time to both encode and decode which can add some latency to the entire process but in some cases is worth the tradeoff because it can transfer the same quality video as MPEG4 can while using only half as much bandwidth 29 Figure 26 Axis 214 PTZ camera 5 There are two basic types of cameras intended for monitoring purposes fixed and PTZ Pan Tilt Zoom Both can come with or without a dome the purpose of such being to hide the current position of the camera prevent vandalism and protect the lens and onboard electronics from the elements for outdoor use A fixed camera is used in applications where the position angle and focal distance of the area being monitored are constant such as a camera pointed downwards at a cash register in a convenience store Fixed cameras typically have no optical zoom but sometimes have exchangeable lenses or an adjustable focal range on the lens apparatus itself This also changes the field of view which is how wide of an angle each frame captures 30 AAS Figure 27 Axis 212 Wide Angle Camera 5 PTZ cameras are useful in larger open spaces or where there s no fixed angle that needs t
21. and battery voltage indicators The mounting locations of these sensors can be seen in Figure 33 Limit switch for joint twe Tr pot OOF Pots for joint one and two Switches for joint one Figure 33 Robot Sensor Suite 41 The robot returns position feedback to the user interface in the form of a computer generated model providing an intuitive method for operating the robot These sensors not only provide feedback to the user but also transmit information to the robot s safety control system preventing self inflicted damage due to improper user direction In addition to position feedback pressure sensors are attached to the claws of the outer gripper giving the operator real time updates of the clamp force exerted by the claw Linear passive pressure sensors are utilized for this application because of their simplicity and durability A ranging sensor system provides the distance feedback for the operator to aid in orienting the disruptor and gripper mechanisms This system utilizes an infrared range finder excelling at longer ranges up to four feet as well as rough materials An ultrasonic sensor is also included to verify the return distance while increasing the accuracy at short distances of less than two feet as well as on smoother surfaces The modular design of the robot makes it possible to mount additional mission specific sensors as needed including x ray or ultrasonic imaging equipment or a Geiger cou
22. and carry objects as well as a means to resist the motion of the inner gripper A 150Ib actuator is used to drive the opening and closing of the outer gripper These two grippers can be used together to improve the overall dexterity and manipulation capabilities of the robot 39 Figure 31 Physical Gripper Figure 32 Gripper CAD Model C Base Design The robot design uses a wheelchair base rather than a custom designed platform allowing for faster design and prototype development of the gripper and manipulator arm The wheelchair base contains a differential drive system which provides the needed mobility in terms of maneuverability and speed The maximum speed of the robot is seven miles per hour but it can be easily controlled at much slower speeds The power source on the wheelchair is also large enough to power the entire robot system for several hours of continuous operation Anti tip wheels and intelligent braking with electronic regenerative disk brakes help to aid the drivability of the base The base also serves as a stable platform to house the robot arm for manipulation tasks At the production stage custom designed base platforms can be used to provide smaller and lighter alternatives with high mobility Table 6 Acceleration and Maximum Speed Testing Results Acceleration 5 yard dash Maximum Speed 30 yards at from stop full speed Test 1 2 9 seconds 9 1 seconds Test 2 2 9 seconds 9 2 seconds Test
23. arm joint etc Name Pin Port Pin of Destination Packet Connector ID Motors Pin Port Pin of Destination Connector Left Drive Motor Signal Port1 DIOO 23 24v Motor 1 Left Drive Motor Ground D GND 24 24v Motor Controller Right Drive Motor Signal Portl DIOI 25 24v Motor 2 Controller Right Drive Motor Ground D GND 26 24v Motor Controller Arm Joint 1 Signal Port1 DIO2 27 24v Motor 3 Controller Arm Joint 1 Ground D GND 28 24v Motor Controller Arm Joint 2 Signal Port1 DIO3 29 24v Motor 4 Controller Arm Joint 2 Ground D GND 30 24v Motor Controller Arm Wrist Joint Signal Port1 DIO4 31 12v Motor 5 Arm Wrist Joint Ground D GND 32 12v Motor 83 Controller Big Claw Actuator Signal Port1 DIOS5 33 12v Motor 6 Controller Big Claw Actuator Ground D GND 34 12v Motor Controller Small Claw Extend Signal Port1 DIO6 35 12v Motor 7 Controller Small Claw Extend Ground D GND 36 12v Motor Controller Small Claw Close Signal Port1 DIO7 37 12v Motor 8 Controller Small Claw Close Ground D GND 38 12 Motor Controller Sensors analog Pin Port Pin of Destination Sensor ID Joint 1 Pot Power 5V 48 Port9 Joint 1 Pot Signal AIO 2 1 Joint 1 Pot Ground D GND 50 Port9 Joint Z2 Pot Power 5V 48 Port9 Joint 2 Pot Signa
24. commonly used to assist in stair climbing and counter balance the robot for a higher lifting capacity Other mechanisms may also be included in the base to redistribute the weight allowing for heavier lifting 12 Wheeled Study Results Vehicles Vehicles Route Flexibility 4 Cross Country Mobility Traction on Slopes Road Speed Logistics O amp S Costs GVW Volume amp Payload Maneuverability Turning Radius Transportability Weight Growth Potential Gap amp Obstacle Crossing Figure 9 Comparison of Tracked vs Wheeled Vehicles 10 Summary of Mechanical Features A comparison of the key mechanical features of researched robots is shown in Table 2 These robots range in weight from 50 to 550 pounds capable of driving at speeds ranging from 0 23 to 5 8mph There are several different arm designs allowing for anywhere from three to five degrees of freedom A wide range of reaches are available from vertical reaches over 100 inches to horizontal reaches nearly approaching this value The pressure that robot grippers can exert ranges from 20 to 115 pounds These values are largely dependent on the amount that the gripper opens 14 Table 2 Comparison of key features of competitive EOD robots Values dependent on accessories installed Ground in Max Horizontal Reach from base in Max Lifting Capacity Ibs Gripper Pressure Ibs Max Gripper Opening in Max Speed mph amp A
25. controller implements a standard PID loop for control These changes in location are limited by a slew rate Slew rate 1s the rate of change of the process variable in this case motor output The final position requested is also limited to the operational range of the robot The output of this loop is then fed to the velocity controller The next level down is the velocity controller This controller takes the change in position the robot arm has traveled and divides the value by the amount of time that has passed during the change in position After calculating this actual velocity it compares it to the desired velocity provided by the position loop This is done through an advanced anti wind PID loop The output of this loop 15 then slew rate limited to avoid voltage spikes in the motor and used as part of the actual motor voltage output This output is measured in percent of total voltage 24 volts for the robot BDR _Engine vi Block Diagram i RIO File Edit View Project Operate Tools Window Help 5 8 e m e RA bole pt Application Font 7 sta Sea Iteration Duration Safety Timeout Get Set Safe or Move 7 7 Move Packet loureur 383 BDR Enginexi Front Panel on BDR2 Ivproj RT Single Board RIO Edit View Project Operate Tools Window Help m 15pt Application Font Bo 8 9 mj Project Bomb Disposal Rob
26. for each analog value If there s a queued up command related to a button such as the emergency packet toggling the safety switches on or off this thread sends it and erases it from the queue which is checked every 100ms Packet Structure Since alternate signal confirmation protocols are being used bandwidth can be saved and packet communication facilitated by using the User Datagram Protocol UDP Unlike the Transmission Control Protocol TCP where there is an acknowledgement ACK packet sent from the original receiver back to the original sender the UDP can just send a packet out to a specific IP or all addresses on the local subnet and won t receive any packets back containing ACKs The packets sent are usually only a few dozen bytes long due to excessive overhead being eliminated by creating a customized packet structure As shown in Appendix there are four different types of packets that the controller unit can send to the sbRIO onboard robot controller They are the GET packet MOVE packet SET 58 packet and SAFE packet The sbRIO will only ever return one packet type RETURN which contains sensor values to return The common structure among all packets are the first three bytes The source which is either a 1 to designate that the packet originated from the controller or a 0 to show that it originated from the robot The next byte is the Action which typically contains the first letter of the packet type and
27. monitoring done by the robot controller more details found in safety design section The response of the system is shown in Figure 47 64 mee ry 3 Figure 47 Cascaded PID Slew Rate Added The response of this system 15 actually able to settle unlike previous iterations The spikes shown in Figure 47 are actual contacts on the arm from outside forces to ensure that the robot arm re settles at the desired position Since each sample is taken at 100Hz it can be determined that the arm settles in slightly under one second There is still some steady state error that can be fixed throughout the system as the graph shows Ideally this should happen by slightly raising the integral term on the velocity controller allowing the output to accumulate with the integral term and eventually fixing the error 65 VII Results The robot prototype was fabricated and assembled then taken through a series of testing This section outlines the final specifications of the system as well as a look at the mechanical systems user interface wireless capabilities and a cost analysis of the robot A Finished Robot Specifications Dimensions e Height arm and boom camera stowed 38 e Height boom camera attached 70 e Width 26 e Length Arm stowed 54 e Max Length arm at full extension 96 e Horizontal Reach 56 e Ground Clearance 3 Weight fully loaded 312 165 Drivability e Top Spe
28. only method of bomb disposal The method of communication is often costly can lead to a range of problems Wired communication is commonly performed using fiber optic cable Fiber optic cable is highly susceptible to breaking and can be crushed by passing vehicles or the robot itself For the robots that do not use fiber optic cables wireless radio transmission B Sensor Feedback There is an apparent lack of sensor feedback in the current EOD robots on the market This problem could be easily solved with the addition of simple sensors such as potentiometers limit switches range finders and pressure sensors Potentiometers could be used to provide the operator with real time position feedback from all links of the robot arm Limit switches would increase the safety of the system and prevent the robot from colliding with its own systems Range finders would allow more precise alignment of the gripper and arm while pressure sensors would allow the operator to cautiously grip delicate objects Figure 3 Visual Arm Position Feedback of the Andros F6A Robot C Controls and Control Software Each EOD robot manufacturer has a unique user interface to control their robots These user interfaces vary from applications that run on standard computers to custom built units The MARKBot uses a control program that can be installed on any windows computer with wireless capability This program takes input from an Xbox 360 controller allowing the
29. or user induced In order to properly fire the disruptor an encrypted specific packet must first be used to disable the disruptor safeties before the fire command can be followed Motor Control System The robot implements a double loop control system to maintain the stability of the arm As shown in Figure 38 the system is broken down into four separate pieces namely the velocity controller position controller system model and the limit sets 50 User Input Joystick esi poi Position Calcuator ZU Current Pi S Position 4 Position PID Output is joint 7 velocity Cu a Velocity Calculator 5 Outputis direct motor voltage A Master Clock Safeties input Limit Switch input Safety Y Contra ena Motor Output output Figure 38 Cascaded PID Arm Control System The position controller is the highest level of the motor control system This controller takes the analog input of the potentiometers monitoring each joint and determines the next position the arm should go This destination is dependent on the input of the controller For instance if the controller sends a zero the arm will hold position and let its next position be its current position If the user wants to move the arm slightly forward the algorithm will choose a value forward of the current position that is proportional to the speed at which the user wants to 51 move This
30. state error correction The feature is accomplished by creating a memory of the integral term and clearing old non relevant values Although the single PID system described above was implemented it did not succeed in controlling the arm The control system response on the arm resulted in a severe oscillating motion Although tuning the PID loop did help the correct tuning parameters were position specific resulting in a different system response depending on the position of the arm This oscillating motion is showed in Figure 43 where the arm process variable constantly overshoots the setline 60 PID Loop Simulation Process Value Set Point Output 3 o c gt o a a 5 a z o Time sec Figure 43 Oscillation motion PID Simulation The reason for these problems came from several mechanical factors on the robot First the innovative gripper attachment at the end of the arm is quite heavy resulting in radically different torques required to drive the arm at the same velocity if the positions are different Second the arm system onboard the robot is not close to an ideal system The slop gained from the chain gearbox and motor cause significant delays of force transmission in the system As a result the robot will continue to increase the output but not see the result until a set delay later making it significantly harder to control C Iterati
31. that include the capability to create user interfaces C has libraries that allow easy creation of a user interface Java has a similar system with a couple of different options for what library to use The java swing library allows for easy and quick construction of a graphical user interface or GUI This library includes objects such as buttons text boxes and panels By using these objects it is possible to create any user interface that can be thought of There are two main ways to create these interfaces the first is by writing code directly then testing it The second method to create a GUI is to use a tool that is specifically designed to create a user interface such as NetBeans SWT AWT are java libraries that are designed to be used in the same manner as the swing library The libraries for C are also built with the same concepts in mind as the swing library D Mechanical Systems Manipulator Arm EOD robots require some form of arm to perform basic functions This arm can range from a short linkage to hold a disruptor to a large six degree of freedom robotic arm with gripper claw The arm design will vary depending on the robot s utility but the basic ability to reach and manipulate the targets is important to all systems Figure 7 MURV 100 High Rise Arm for Aircraft Applications 6 The arms ability to reach the target is often hard to predict because bomb threats can occur in a wide range of locations in
32. the initial software was developed to lay out the structure and layout of the GUI and controller as well as software that controls the arm dynamics Prototyping Integration and Testing This stage is essential to confirm that the system will work and meet the task specifications Several iterations of mechanical designs and software coding will be made Creating prototypes of any complex mechanical systems will allow for revisions to be made in the design before manufacturing begins Similar processes can be done with the software by revising models and control architecture Final Design The results of the prototyping and testing will yield changes to be made to the design Once these changes are made the final design should be modeled manufactured and tested 34 IV Mechanical and Hardware Design The robot features several different mechanical and hardware systems A three Degree of Freedom DOF arm is mounted to an electronic wheelchair base that provides a rugged yet relatively compact mobile unit to build off of An innovative end effector makes use of a dual gripper design to allow the operator to manipulate objects in a way never before possible and specifically facilitates the neutralization of a blasting cap or detonator The onboard CPU continually checks for and processes data from all sensors not limited to but including potentiometers for feedback ranging sensors pressure sensors on the end effector and limit switches for
33. weight and motion of the arm In order to calculate the basic forward and inverse kinematics of the arm the coordinate transformation matrices must first be derived For a given link number i the Denavit Hartenberg D H parameters shown in Figure 29 summarize these transformation equations Figure 29 defines variable locations on the arm s coordinate axes Table 5 D H parameters of arm a D 0 0 48 0 0 0 0 2 2 0 05 0 1 2 0 94 Where l offset along the previous z axis to the common normal angle about previous z axis D length of the common normal 0 angle about common normal 36 Link i Length m li 0 48 191 0 20 8 0 94 371 Joint 1 Figure 29 Kinematics Analysis of Arm The coordinate transformation matrices were calculated for the arm as shown in Equation 1 For a given vector B in base coordinate system Equation 2 allows for the transformation into the final coordinate system end effector system The result is represented by vector A Equation 1 Coordinate Transformation Matrices cos0 sin0O 0 0 sin0 5 0 d 1 0 0 T 5 cos0 0 0 lee 0 010 10 0 0 0 10 1 0 001 0 0 0 0 1 0 1 000 1 Equation 2 Vector Transformation A T xB Torques can be calculated on the arm as expressed using the Lagrangian equation as sho
34. 0 1 Million Contract Military amp Aerospace Electronics 13 Apr 2011 Web 21 Apr 2011 lt http www militaryaerospace com index display article display 7846206058 articles military aerospace electronics online news 2 2011 4 navy to_continue_buys html gt Luminary Micro First Robotics Competition Luminary Micro Stellaris the Industry s First Cortex M3 MCUs Web 21 Apr 2011 lt http www luminarymicro com jaguar gt Mesa Robotics Inc Matilda II Madison AL Online NI sbRIO 9612 9612XT Embedded Devices with Analog Input and DIO 2M Gate FPGA National Instruments Test Measurement and Embedded Systems National Instruments Web 26 Apr 2011 lt http sine ni com nips cds view p lang en rid 205898 gt Nicopolitidis P 2003 WIRELESS NETWORKS p 190 Chichester England Hoboken NJ John Wiley amp Sons Ltd UK 2003 78 27 28 29 30 31 32 33 34 35 36 37 38 39 NTT 2010 03 25 World Record 69 Terabit Capacity for Optical Transmission over a Single Optical Fiber Press release http www ntt co jp news2010 1003e 100325a html Retrieved 2010 04 03 Pololu Pololu Simple High Power Motor Controller 18v25 Pololu Robotics and Electronics Web 21 Apr 2011 lt http www pololu com catalog product 1381 gt Robert L Norton Design of Machinery 4 edition McGraw Hill New York NY 2008 pp37 40 Products North
35. 120 LOCK NUT FLANGED 5 16 18 1 N A N A MCMASTER PN 93298A125 LOCK NUT FLANGED 5 1624 1 N A N A 100 300 ARM 1 N A MP 36064 540 BANEBOT MOTOR AND PLANETARY GEARBOX 12V 1 N A N A 00 301 SQUARE TUBING ARM LOWER LINK 2X2 0 125 THK 1 AL M CNC SQUARE TUBING ARM MIDDLE LINK 2X2 0 125 00 302 THK 1 AL M CNC SQUARE TUBING WRIST ROTATION MOTOR 00 303 SLEEVE 2X2 1 AL M CNC 00 304 LINK 8IN ACTUATOR JOINT AND BASE MOUNT 4 STEEL WJ 00 305 LINK ACTUATOR JOINT BASE SIDE 2 STEEL WJ 00 306 SHAFT ACTUATOR 8IN 1 N A N A 00 307 FLANGE LOWER ARM JOINT 2 STEEL WJ 00 308 ATTACHMENT 8IN ACTUATOR NOSE MCMASTER PN 6793K110 SPROCKET CHAIN DRIVE LOWER ARM LINK 2 N A MANUAL MCMASTER PN XXX CHAIN LOWER ARM LINK 1 N A N A 100 310 END CAP 2X2 SQUARE TUBING ARM DRIVE 1 STEEL CNC 2 X2 X2 MCMASTER PN 92220A175 LOW PROFILE MACHINE SCREW 10 32 X 1 2 4 N A MCMASTER PN 92220A171 LOW PROFILE MACHINE SCREW 10 32 X 1 4 8 N A N A MCMASTER PN 91259A537 SHOULDER SCREW 225 X 1 4 2 N A MCMASTER PN 93298A108 LOCK NUT 10 24 75 N A N A MCMASTER PN 90298A551 SHOULDER SCREW 1 4 X 2 75 1 N A N A MCMASTER PN 97345 A489 SHOULDER SCREW 5 8 X 3 16 1 N A N A 81 Appendix II Electrical Pin out for sbRIO Arlle Pinout Note Grounds for outputs are on same connector as signals Note 2 Arm joints are signified by lowest joint first i e 1 arm joint is the base
36. CE DECIMAL MEG APPR TOLBRANONG PSE MATERAL DO NOI SCALE DRAWING 3 2 0 500 fb TE LINK ESSENTRIC CRANK OUTER GRIPPER 100 005 92 1 000 BOTH SIDES UNLESS OTHERWISE SPECIFIED NAME DIMENSIONS ARE IN INCHES DRAWN CHECKED TWOPACEDECMAL 20 THREE PLACE DECIMAL t APPR CONFIDENTIAL porem COMMENTS Petre MAIEMAL ALUMINUM COMPANY ANY INE INCURRERE OR NEXT assy ON COMPANY 5 APPUCADON NOI SCALE DRAWING 5 4 1 000 15 250 1 455 2X 9313 250 THRU ALL THRU ALL 2000 1 815 125 8 000 2 000 500 2X 1 000 563 4x Q 159 THRU ALL UNLESS OTHERWISE SPECIFIED NAME DIMENSIONS ARE IN INCHES DRAWN CHECKED MO PACEDICMAL 200 2 RACE MEG APPR PROPET AMD CORPIDEMTIAL INFORMA DON CONTAINED IN THS MATERAL pem DRAWING I5 SOLE PROPERTY CF COMPANY ANY m NET assy umon COMPANY HSD APPUCANON DO SCALE DRAWING THLE EMD CAP 2X2 SQUARE TUBING GRIPPER SIDE SUE DWG NO 100 009 SCALE 1 1 WEIGHT SHEET 1 OF 1 TE SQUARE TUBING ACTUATOR HOUSING 2X2 0 125 THK SIZE DWG NO A 100 008 SCALE 1 5 WEIGHT SHEET 1 OF 1 1 93 lt 777 250 4 77 THRU ALL 250 2X R 125 H 250 2000 __ 6250 375
37. Many camera manufacturers that specialize in security and monitoring solutions make dozens of different network cameras and some companies don t even produce an analog line With an IP camera all of the encoding and compression is done in the same small package as the camera itself simplifying both installation and implementation Many network cameras also support PoE Power over Ethernet to further facilitate installation since a power outlet doesn t even need to be nearby This means only a single wire needs to be plugged in to handle power user configuration and viewing the actual video stream Almost every IP camera comes with one two or three different supported codecs for encoding the network stream before the signal even leaves the camera to be broadcast over the network MJPEG Motion JPEG is the most simple of the three and requires hardly any resources to decompress and view since it s essentially just a stream of JPEG images coming in at a specified frame rate This is useful when the camera is capturing significant movement in the field of view because it hardly takes any time to output due to a lack of significant compression If the available throughput is a limited resource choosing an encoding method such as 4 or H 264 might be more suitable It s important to note that even though these latter two alternatives don t perform as well under action intense conditions one is still usually preferred over MJPEG due to the large
38. PROGRESSIVE AUTOMATIONS 1 N A N A 100 012 SHAFT LOIN ACTUATOR 1 N A N A 100 013 SHAFT 4IN ACTUATOR 1 N A 100 014 ACTUATOR NOSE MOUNT BRACKET 1 AL CNC 2 25 5 1 5 100 015 ACTUATOR NOSE MOUNT FOR INNER GRIPPER 1 AL CNC 2 25 X 1 5 1 5 MCMASTER PN 973454458 SHOULDER SCREW 5 32 X 1 2 1 N A N A MCMASTER PN 91259A540 SHOULDER SCREW 1 4 X 3 4 1 N A N A MCMASTER PN 91259A544 SHOULDER SCREW 1 4 X 1 25 4 N A N A 80 MCMASTER PN XXX CLEVIS PIN OUTER GRIPPER 8 N A N A MCMASTER PN XXX COTTER PIN FOR CLEVIS ABOVE 8 N A MCMASTER PN 92220A184 LOW PROFILE MACHINE SCREW 1 4 20 X 5 8 8 N A N A MCMASTER PN 92220A176 LOW PROFILE MACHINE SCREW 710 32 X 1 4 N A N A MCMASTER PN 92220A173 LOW PROFILE MACHINE SCREW 710 32 X 1 2 8 N A N A MCMASTER PN 92220172 LOW PROFILE MACHINE SCREW 10 32 X 3 8 36 N A N A MCMASTER PN 9222A174 LOW PROFILE MACHINE SCREW 10 32 X 5 8 16 N A N A MCMASTER PN 91259A103 SHOULDER SCREW 1 4 X 2 1 N A N A 100 200 AXIAL BEARING WRIST MOTOR N A 100 201 GRIPPER MOUNT BEARING MOUNT WRIST MOTOR 1 STEEL CNC 3 X3 X 1 ARM MOUNTING BLOCK BEARING MOUNT WRIST 100 202 MOTOR 1 STEEL CNC 2 X 1 5 MCMASTER PN 6384K365 BEARING FLANGED 5 16 BORE WRIST MOTOR 1 N A N A 100 203 SHAFT BANEBOTS MOTOR KEYED 1 STEEL MCMASTER PN 93298A
39. T SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 3 2 1 100 2 750 1 750 BOTH SIDES 4X 10 32 TAPPED HOLE 4 500 22 4X 194 THRU ALL CHECKED MACH EEND S APPR TWO PIACE DECIMAL PLACE DECIMAL MFO APPR CECMETISC QA PROPRE CONFIDENTIAL TOLRANONG PER JHENFORMADCH CONTAINED IN me A DRAWING IS PE SOLE PROPEN Y CF PART OR ASA WHOLE RE COMPANY APPUCATON DONOTSCALEDRAWRG 5 4 3 mE END CAP 3X3 SQUARE TUBING SIZE DWG NO REV A 100 007 101 Appendix V User Manual 102
40. TO ENABLE DISABLE 1B Arm A dec 65 Base B dec 66 Everything Master M dec 77 Disruptor D dec 68 VALUE 1B Value 0 disable or 1 enable Packet data length 4B RETURN Packet This packet is sent from the host to obtain sensor data from the sbRIO Packet Structure SOURCE 1B SOURCE ROBOT 0 when the value is being returned ACTION 1B GET 71 decimal for NUMBER OF DEVICES 1B The number of devices being requested or returned in this packet DEVICE ID 1B The device ID that a value has been returned Denoted as on pinout 88 VALUE 2B RETURN PACKET ONLY THESE TWO BYTES DON T EXIST IN REQUEST when source 1 The value of the device above Packet data length 6 B 6 is the minimum the sbRIO will send back 89 Appendix IV Mechanical Drawings of Key Components MY UNLESS OTHERWISE SPECIFIED NAME DATE son DRAWN TABANCE pomum TILE LT NIA FINGER THREE PLACE DECIMAL APPR kd OUTER GRIPPER AND CONFIDENTIAL TOURANONG PER SIZE NO CONSE COMPANY NAME HERE ANY LL wow 100 001 APPLICATION DO NOT SCALE DRAWNO SCALE 1 5 WEIGHT SHEET 1 OF 1 5 4 2 1 9 7 250 2X R 375 X925 S 1050 CHAMFER 750 UNLESS OTHERWISE SPECIFIED NAME DATE DIMENSIONS ARE IN INCHES DRAWN TLE udi ENG APPR L N THREE PLACE DECIMAL t
41. TOR pente EEL SWE DWG NO EE 100 202 7 mn APPUCATON DO NOI SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 2 1 98 1050 CHAMFER 2278 4X10 32 CLEARANCE HOLE 3 536 THRU ALL 4X R250 THRU ALL 2X R313 LINK 8IN mex ACTUATOR JOINT morsus ue Comat LT AND BASE MOUNT pente hon SUE DWG NO Soe A 100 304 DO NOT SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 2 750 250 senators eo LINK ACTUATOR JOINT BASE SIDE mer SUE DWG NO mum 100 305 foenore APPLICATION DO NOT SCALE DRAWING SCALE 1 1 WEIGHT SHEET 1 OF 1 99 050 CHAMFER 250 zt L 188 d 9250 THRU ALL THRU ALL DIMENSIONS AREN INCHES DRAWN FRACTIONAL CHECKED THLE BEND FLANGE LOWER ARM JOINT COMMENTS mex SUE DWG NO 100 307 NEGASSY umon eo emt APRUCAVOR DONOTSCAEORAWNG _ SCALE 1 1 WEIGHT SHEET 1 OF 1 5 4 2 1 1 500 2x 250 THRU ALL wos mE END CAP 2 2X2 SQUARE TUBING 5 m aec En ARM DRIVE Demos p SWE DWG NO See 100 310 ars APRICATION DO NO
42. and prevent cutting from sharp rocks or stress This would only require minimal video compression and would provide a reliable means of both video and data communication for well over a mile 13 Unfortunately any sizable length of ruggedized thick cable is going to add significant extra weight and require mechanisms for deployment and re spooling Depending on the thickness it likely wouldn t even be possible to achieve an adequate distance because the spool of cable would be larger than the robot itself Figure 11 shows that a fiber optic spool is bulky and requires extra onboard equipment for the spooling mechanisms and this would be much lighter than copper cabling instead Fortunately there is an alternative to the tethered approach wireless communication Cell phones are excellent examples of devices used every day that communicate with a transceiver tower sometimes located several miles away Newer mobile networks are utilizing LTE for 4G mobile data and voice services By using different modulation and encoding 16 techniques similar amounts of bandwidth that were used in previous cell networks can provide throughput speeds almost as high as a typical consumer CAT 5e cable with unbelievably low latencies 25 Using this technology for a mobile robotic application would be an excellent choice if the only areas of operation were going to be in the top ten largest cities in the country The service is so new that it is only just beginn
43. bps and 802 11b coming in at 11 Mbps Although 802 11n is more effective at combating the problems of multipath interference objects obstructing the line of site communication between the base station and client it s also more expensive and typically requires a multi antenna setup It does have the added bonus of being able to operate at 5GHz where there is less interference but it s more often used at the normal 2 4GHz part of the spectrum due to slightly better range in real world applications Comparing 11g and 11b the sacrifice for the speed increase in the former is a much smaller area of coverage meaning that the latter can cover much more distance before the signal strength drops off below the threshold 18 To increase the distance even farther a combination of omnidirectional and directional antennas can be used or even two directional antennas if the application is stationary F Hardware Components 1 Motor Controllers Motor controllers are electronic components that provide controlled power to the motors Typically they are connected between the battery and the output device controlled by a low power input signal such as PWM or CAN Pulse width modulation PWM is a signal that is often transmitted to motor controllers to control the motor speed It works by controlling the duty cycle of the signal and is usually measured in a percent value of the voltage on or high time over of the period For example if t
44. cluding vehicles trash cans or dumpsters closets bags and other obscure areas The arm should therefore be designed to reach a variety of locations Many robots are designed for specific applications such as the HDE MURV 100 with a high rise arm designed for aircraft EOD missions 6 The arm must be able to reach inside overhead luggage bins at heights up to eight feet see Figure 7 Another aspect of reaching the target is the ability to open doors break glass and lift objects For this reason most robotic arms contain a gripper claw Gripper Claw The gripper offers the ability to manipulate potential targets as well the ability to reach and view these threats Just like with the arm there are several different designs for gripper claws each providing the user with the ability to lift drag and carry objects as well as open doors and compartments The Talon Scarab IIA Caliber Packbot MURV 100 MK2 ROV Pedsco and Matilda robots all have small grippers designed to pick up smaller objects The Andros Knight and MR 5 robots have much larger grippers allowing them to pick up a wider range of objects There are also many ways to control the opening and closing motion of the gripper The Andros and Knight robots use a standard four bar linkage drive system to power the gripper This system is advantageous as it can provide a high level of mechanical advantage if transmission angles are optimized Many smaller gripper designs are driven usi
45. d transceivers combined with DSSS modulation should prevent this interference from corrupting packet data 47 1 2 3 4 5 6 7 8 9 10 1 12 13 14 Channel 2 412 2 417 2 422 2 427 2 432 2 437 2 442 2 447 2 452 2 457 2 462 2 467 2 472 2 484 Center Frequency 22 MHz Figure 36 802 11 Bandwidth Layout 7 To test the robot s line of sight wireless connection the signal quality and signal strength were tested every ten yards for 170 yards as seen in Figure 50 in the Results section The directional panel antenna was placed on the ground for this test but it was later noted that when the antennas are on the same horizontal plane both the signal strength and the signal quality are much greater compared to when they are not at the same height This can be explained by the fact that the omnidirectional antenna is isotropic or a source from which the signal extends outward from B Onboard Processing As previously mentioned in the Control Hardware section the robot s onboard systems are controlled by a National Instruments single board control unit sbRIO Aside from the basic I O monitoring there are three main pieces to the on board software These pieces are the Ethernet parsing control safety system and the motor output control All code written for the SbRIO was created in Labview Ethernet Parsing By far the simplest of the three systems this system is responsible for taking the packets from the computer and transfe
46. e settings will always remain the same An example of this is the left joystick which is assigned to an arcade style single joystick driving control The user will need to be able to drive the robot at any time and in any mode The most important button that always has the same functionality is the Start button which sends an enable or disable Emergency packet to flip all the safety switches at once With regards to different modes the user can always hit X to cycle through camera mode and arm mode while A is used to switch between inner and outer gripper modes Since these buttons determine the functionality of the remaining three axes they need to be able to change them at any time It should be noted that these modes do not exist on the robot side they re only to assist the operator with sending the right packets when s he means to The left bumper can be used to cycle through and select main arm links even though they can only be controlled in arm mode and the right bumper can always cycle through the different camera feeds The right joystick or non driving joystick if the controls are reconfigured has a 40 threshold setting compared to the driving joystick s 15 The minimum threshold for any joystick should be 15 because when released the joystick rarely returns to the exact center and in testing was found to be up to 1596 off the center point on a single axis These threshold values 54 mean t
47. e e 2 Figure 2 The Team with the Andros F6A Robot sess 5 Figure 3 Visual Arm Position Feedback of the Andros F6A Robot eee 6 Figure 4 Andros UL Display iss aee conten rer eir e o e ards iori tu i dd dn 7 Fig re 5s Phe Talon Cotnttoller i os tata dni s 8 Figure 6 The Andros ea eoo tena p aS Nena ma Sd 8 Figure 7 MURV 100 High Rise Arm for Aircraft Applications 6 eese 9 Figure 8 iRobot s Packbot Fires a Disruptor 211 2 22 100000 12 Figure 9 Comparison of Tracked vs Wheeled Vehicles 10 sene 13 Figure 10 Andros F6A Wireless 17 Figure 11 Andros Dash with Fiber Optic sese 17 Figure 12 PWM control at different duty cycles 19 Fig re 13 H Bridge Circuit LL aseo tif ti m e d dis 20 Figure 14 Cytron Motor Controller 5 ise sae oat aetna ac 20 Figure 15 Sabertooth Motor Controller 7 21 Motor Controller ene tuni od ai teas ted 21 Figure 17 Pololu Motor Controller 21 Figure 18 Simple H Motor Controller sis erret ee ette cree 22 Figure 19 Black Jaguar Motor Inna loa hu NER Reps da 22 Figure 20 C ANBUS 281 rni 24 F
48. e primary benefit of going through this process for the robot was to drastically increase the transmission power At the factory this setting is set to default to 23 mW 14 dBm but this customized software allows the transmitter to send at up to 251 mW 24 dBm It s important to note that a greater transmission power doesn t necessarily correlate to a better signal since with standard routers since the components are not designed to be operating at that power level This can cause them to overheat and fail or be responsible for noise and corruption on the channel prior to failing when the components are used outside of their specified temperature range After 46 initial testing the router was set to a recommended 80 mW 19 dBm for optimal performance Other minor changes were made to optimize the router for our needs such as disabling the WAN port and using it as an additional LAN connection To further increase range and throughput the 3 dBi stock antenna was replaced with a 15 inch high gain 9 dBi omnidirectional antenna to account for the robot being in any orientation while driving without affecting the signal For the laptop running the control software on the user interface side a wireless USB adapter is outfitted with a high gain 7 dBi directional panel antenna that can be aimed in the general direction of the robot during operation The controller unit s antenna does not need to have as high a gain as the robot s antenna because
49. e research performed on existing robot systems before design work began This phase involves investigating exiting EOD robot systems and performing basic market research to determine desirable and undesirable features The key aspects of research include a Market Research Involves interviews with bomb technicians to review advantages and flaws of currently available robots b Sensor Feedback Explores basic sensors that would aid in EOD missions c Controls and Control Software Study of the controller and GUI software and the hardware control architecture d Mechanical systems Research into the mechanical design of robot systems including base arm and gripper design e Communication Research into current methods of communication and review of the systems currently used on robot systems Further research was performed to determine range requirements and signal limitations and restrictions f Hardware components other hardware components such as controllers batteries motor controllers and sensors were researched A Market Research Basic market research was performed to understand the key desirable features of existing robot platforms A large portion of this information was obtained through an interview with the Boston Bomb Squad In this interview the team investigated three primary robot platforms including the Talon by Foster Miller the Remotec Andros F6A and HD 1 robots by Northrop Grumman Other smaller systems w
50. ed 6 75 mph e Reach max speed in 2 93 sec e Anti tip wheels e Intelligent braking with electronic regenerative disk brakes Arm Capabilities e Lift capacity at full extension 5 158 e Lift capacity max 30 16 e 3 DOF e Multiple approach vectors Gripper Capabilities e Gripping strength of outer gripper 47 Ibs e Outer Gripper Opening 12 in e Gripping strength of inner gripper 6 165 e Inner gripper reach 12in e Inner gripper opening 6in 360 rotating wrist Operator Control Unit e Control Intuitive Xbox 360 controller e 3 Continuously streaming camera views e Easy view cycling e Arm position feedback 66 e Displays important feedback from robot Onboard Sensors e Pressure sensors on outer gripper claws e Ultrasonic and IR range finders on gripper e Arm joint position sensors e Battery levels Batteries e Two Lead Acid 12Vdc batteries e Rechargeable e Life at typical operation 3 4 hours Communications e Wireless communication using 802 11b e Tested range 170m line of site Cameras e Mechanical PTZ boom camera 360 180 216x e Wide angle 140 digital PTZ drive camera e Gripper camera Additional Features Possible e Geiger counter e X ray imaging e Ultrasonic imaging Recoilless Disruptor Mount e GPS compass mount The initial design specifications are evaluated in Table 7 of our task specifications were met or exceeded in the robot prototype Table 7 Analysis of Initia
51. ee ioe 33 IV Mechanical and Hardware Design uisa Oen aree st dem tasted 35 A Arm Designin 36 Gtipper a 38 Bas e MN EE MR 40 D Sensor Suite ea desea ctp 41 Control ard wares beet ut shades B eed d dd 43 E UE c a 44 V Design of Software and Communication Systems essen 45 A Network Communication 45 B Onboard PROCESS 48 Ethernet Parsing iio ee reti eset ies 48 Safety sti defe sue ecu E Pa 49 Motor Control reae 50 Programming Controller 53 Controller SoftWare 53 c e LL 56 Displaying Video Peeds e in 57 ede ia e n 57 Packet Str ct be ea eeu ERR ERO Aet Ug pete a I 58 Controller Designz ono c dina ette nie co Ecke 59 A MVOC UC CLO I TR 59 B Iteration 1 Standard PID Loop uds eoe ere ENS PA oS UR eap eb NUS 59 C Iteration 2 Standard PID Loop and Experimental System Model 61
52. emember which mode combination is active 55 GUI Layout Real time Position Feedback Port 5020 Width Between Big Gripper 3 2 27 z Inner Gripper Extension 6 0 55 ArmiGripper Mode Big Gripper Amount the Inner Gripper is Closed 100 Camera Mode Inner Claw _ Distance Sensors gt m gt Wheel Driving Velocity of max Distance nearest large _ _ object in front of robot 7 2 feet Left 98 73 48 23 2 27 52 Distance between Disruptor Right amp Target goal 18 inches 21 inches Connection Status Battery Levels Connected to network BDRMQP 12V 11 90V OK 24 23 88V OK Figure 41 Graphical User Interface Display The GUI can be best described by dividing it into four quadrants The top left of the screen shows the primary video feed while the bottom left quadrant shows the two secondary feeds These were positioned in this format so the largest part of the application is dedicated to the currently most important video feed Instead of the operator having to move their eyes to a completely different part of the screen they can quickly reference the two feeds below the primary one to see if they can provide a more appropriate viewing angle for the task at hand Rather than relying on cameras to view the current position of each link the two main links are displayed with positions updated i
53. ere also discussed and demonstrated for comparison and explanation of key features A picture of the team with the Andros F6A robot can be seen in Figure 2 From these discussions several key areas for improvement were unveiled Figure 2 The Team with the Andros F6A Robot One area of improvement for EOD robots is the use of sensor feedback Many robots such as the Andros robots rely solely on visual feedback for remote operation requiring the technician to aim a camera down towards a chart on the arm as a method of avoiding collisions with other components of the robot shown in Figure 3 Similarly many of the investigated robots have no method to detect how far away the gripper is from an object making it very difficult to grab or lift objects much less attempt to disarm bombs Another key deficiency in several existing platforms is the complexity of operation Many commonly used control units are riddled with switches and dials and require extensive training for robot operators A desirable feature in EOD robots is a gripper capable of disarming blasting caps or detonators Bomb technicians from the Boston Bomb Squad noted that an ideal method to disarm detonators would be through the use of a small gripper claw that protrudes from the center of a larger griper This would provide the ability to pull the detonator relative to the explosive device Currently this feature does not exist in any EOD robot systems making detonators the
54. esulted in two percentages signal strength and a link quality Overall the test results as portrayed by Figure 50 shows that even at the max tested distance of 170 yards the signal quality was still approximately 75 Many believe the signal strength is the primary factor in determining if the signal is usable or not but this is not the case IEEE 802 11 defines the Received Signal Strength Indicator RSSI as an arbitrary scale with an unspecified maximum value in 1 byte a maximum range of 0 255 This value is only used by the wireless adapter to determine an appropriate data rate for the signal based on a relative calculated distance from the access point and for 802 11b the data rate would only switch between 11 Mbps and 5 5 Mbps When referring to the Quality of a wireless connection a value from a manufacture s driver usually is the result of doing a Link Quality Analysis LQA This process usually consists of an algorithm comparing the expected DSSS demodulation with the actual result It is possible to compute because DSSS sends redundant bits to account for interference so it doesn t affect the end result As long as the signal quality remains high packets have a lower chance of being dropped and the connection is maintained with higher throughput since resending packets isn t necessary 71 Link Quality amp Strength as Distance Increases 100 90 80 70 7 60 Quality 50 Strength 40
55. hat the operator needs to push the joystick along an axis more than the threshold before the values stray from zero and from that point to their max value they are scaled from 0 100 This ensures that even with a large or different threshold value an analog axis will always return a value between zero and 100 The reasoning behind having these threshold values is because it s rather difficult to push a joystick along only one axis without going a little bit to the side or crossing into a different quadrant in the 360 degree joystick workspace It is especially important for the non driving joystick to have a larger threshold because each axis controls a completely different motor For instance in arm mode the Y axis controls the movement of the selected main link and the X axis controls either the extension amp retraction of the inner gripper if inner gripper mode is also selected or the rotational wrist joint s movement In camera mode that same joystick controls the pan amp tilt speed for the main camera feed if it has PTZ functionality if not it does nothing Similarly the right trigger zooms in and the left trigger zooms out in this mode but again only for PTZ cameras In arm mode the triggers control the opening and closing of either the big gripper or the little gripper depending on what gripper mode it is in All of the current modes and selected links cameras are shown on screen as it would be far too confusing to try and r
56. he details of the system are much more complicated than RS232 the physical layer of the network consists of four twisted pairs of wires containing a voltage difference Figure 22 displays the structure of a standard Ethernet packet which can be sent out as a standalone piece of information This communication standard can be used between two devices or scaled up to global networks Preamble SFD DA SA Info Field FCS LOLOLOLOx Start Frame Destination Source Frame Check Delimiter Addcess Address Sequence 7 bytes 10101011 L6 or 48 bits L6 oc 48 bits Usedto synchronize receiving station s clock Indicates start of frame Universal Local Used to determine Pad size Error checking LLC Data 802 2 Pad Fills Info Field with bits to make up proper frame size Allows unique naming convention Individual Group Soure address always has Individual Figure 22 Ethernet Packet Structure 13 3 Robot Controller A robot controller board capable of receiving sensor input data communication and high speed operation is needed to run these functions on the robot There were three main control boards researched The NI sbRIO the Axon and the FRC 25 sbRIO Figure 23 sbRIO 9612 25 The 9612XT sbRIO board from National Instruments is a potential candidate for the onboard computer This model has a 400 MHz processor 246 MB of storage space and 128 MB DRAM An FPGA is also incl
57. he voltage was held on for half the period then the duty cycle would be 5095 resulting in an output predominately in the center of the values on the motor controller Figure 12 shows PWM control for 10 50 and 90 percent duty cycles The motor controller then uses this duty cycle to control the output voltage to the motor 18 On High Level Off Low Level Figure 12 PWM control at different duty cycles 14 Frequencies used for the period can range from hundreds of Hertz for lights to hundreds of thousands of Hz for audio equipment An advantage of PWM communication is that only a trace amount of current is drawn 14 Motor controllers take in a low current input signal and provide high current power to the motors Although there are many types of motor controllers there is one style that is predominately used to control brushed DC motors This style uses the concept of PWM with an H Bridge application The rapidly alternating on off voltage signal being sent to the motor imitates a variable voltage source For instance if a 24V source was being pulsed with a 50 duty cycle the motor acting as a large inductor would see 12 volts across it and would drive at half speed In order to get this response a high power H bridge must be used An H bridge shown in Figure 13 is a set of transistors that switch on and off depending on the direction of the motor movement desired When used in a switchi
58. id SLA battery Although they are the heaviest and least efficient battery coming in at only 40 60 they re also the cheapest and found in nearly every vehicle used to start the engine Another industrial use is in electric forklifts where a several hundred pound battery is actually beneficial to use as a counterweight as well as a power source One subtype of SLA the Valve Regulated Lead Acid VRLA rechargeable battery is designed for deep discharge and low maintenance recharging It s commonly used in deep cycle marine applications as well as electric wheelchairs and other mobile platforms Nickel Cadmium NiCad batteries are a significant upgrade from SLAs because they are a lot lighter and nearly 90 efficient Additionally they can be recharged several times faster yet remain very robust reliable power sources and offer a high amperage output similar to that of an SLA The downside is that they are a lot more expensive and quite sensitive to cold so much so that they are often carried using the practice of shirt stuffing or holding them close to one s shirt or body to try and keep it warm in cooler climates When efficiency and light weight are of the utmost importance Metal Nickel Hydride NiMH batteries are the next step up While their efficiency approaches the upper nineties percentage wise they are a great deal more expensive than even NiCad batteries For this reason they are usually only used when weight is a major li
59. ig re 21 RS232 24 Figure 22 Ethernet Packet Structure 25 Figure 23 sbRIO 9612 25 26 AUS 24 I IO assa on t t ete Ne utat ME 27 Figure 25 91 2 oret ete teas eet eae e eere Set exo 27 Figure 26 Axis 2 T4 PTZ camera S fttv ista Pato ana 30 Figure 27 Axis 212 Wide Angle Camera 5 cinis iere etd er eet teres 3l Figure 28 Final qiio cpa NE 35 Figure 29 Kinematics Analysis OT AI a SM Mareen areata mn 37 Figure 30 Inner Gripper Design Shown with Closed Half Full Open Configurations 39 Figure 31 Figure 32 Figure 33 Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 Figure 39 Figure 40 Figure 41 Figure 42 Figure 43 Figure 44 Figure 45 Figure 46 Figure 47 Figure 48 Figure 49 Figure 50 Physical COHDDOE GE s eie Itb 40 Gtipper CAD Model a ee e taped tua 40 ROBO LP Sensor SULLO seco ens 41 Hardware Systems OVERVIEW 44 WEIR penu ese See ae ENET 45 802 11 Bandwidth Layout 48
60. igure 21 shows an implementation of RS232 another communications protocol that can be used for this purpose The most basic system only uses three wires a ground wire a transmit wire TX and a receive wire RX Prior to initializing the connection the baud rate must be set either automatically using complex handshake protocols or manually by the user When setup properly the system is extremely easy to use The selected communication speed defines the frequency of each period of information referred to as a bit wide part of D DBS connector Female 4 Pin Handset Modular Plug 123 4 locking tab View with wide part of D on top 1 View with locking 2 tab on the bottom 3 AUTOSTAR PC Serial Port RX RX a a rh TX TX 2 3 GND GND 4 5 Figure 21 RS232 Architecture 4 24 The packet starts with a start bit before transmitting the data bits Usually the data bits are eight bits 1 byte in size per packet allowing a single character in ASCII to be sent per packet This data is followed by a parity bit which determines if a bit has been changed or lost during transmission Lastly a stop bit is sent to let the RX unit know when the packet is finished RS232 communication 15 not designed for large networks but instead it focuses on communication directly between two devices Ethernet Ethernet communication is one of the most widely used communication protocols Although t
61. include a regular analog voltage RC PWM and RS232 As an added bonus the switching frequencies of this motor controller are extremely high 32 KHz allowing for silent operation The cost of the SyRen is 75 Figure 16 SyRen Motor Controller Another motor controller is the Pololu Figure 17 capable of 30V at 20A continuous 35A peak The unit has four control options either USB TTL RC PWM or analog voltage 0 3 3v This product contains many safety features including an over temp overcurrent and slew rate limiter shutdown This controller also comes with a built in USB interface for easy troubleshooting and initial testing Figure 17 Pololu Motor Controller 21 Simple H Figure 18 is motor controller capable of operating at 24V and 25A continuous 45A peak The input type for this motor controller is RC PWM although it requires two PWM signals as an input The H bridge switches at a slow 20 KHz allowing the possibility for audible noise This motor controller costs 70 Figure 18 Simple H Motor Controller The Black Jaguar Figure 19 is a motor controller that allows for a relatively high amount of continuous currents 40A although comes at a cost of a low switching speed under 15 KHz It comes with built in feedback and PID controllers including current feedback and optional encoder feedback and control Figure 19 Black Jaguar Motor Controller 22 Table 3 Motor Controller Summary Table
62. ing to get integrated into the country s largest cities Perhaps this option might be more viable in a handful of years when the 4G service is more widespread Until then another choice is using existing 3G mobile networks Although video would need to be heavily encoded and compressed there s still enough available throughput speed to make it work The downside would be a restricted operation area of wherever cell service was often not in large concrete buildings or underground parking garages either More importantly high latency times up to half a second would prevent an operator from working in true real time significantly impeding use 25 For either of these systems the success of any mission would depend on the reliability of the network since it s beyond the control of a team Figure 11 Andros Dash with Fiber Optic Cable Figure 10 Andros F6A Wireless Tranciever As a replacement for using an already setup infrastructure being primarily used for something else there are different forms of wireless communication that can be categorized as 17 point to point contact One example of this is IEEE 802 11 technology or more commonly simply referred to as Wi Fi This is used to setup a wireless access points in a home or business environment and has a throughput theoretically capable of 600 Mbps if using the maximum number of antennas with 802 11n The other common variants are 802 11g theoretically capable of up to 54 M
63. irap c 36 Table 5 D H parameters of EIE e esee eda re oae tu e ANGE 36 Table 6 Acceleration and Maximum Speed Testing 40 Table 7 Analysis of Initial Design Specifications 67 Table Bo Ads Gameta Donato 2404 506 ot pues La 13 vii Bomb Disposal Robot Prototype A video of the robot in action can be viewed online at http www youtube com watch v vjDu2mlHDTQ I Introduction In the past decade robotic systems have been used with increased popularity for explosive ordnance EOD missions Advances in robotic technology have made it possible for robots to perform functions previously only possible by human workers wearing a blast suit as shown The primary advantage to using robotic systems for explosive ordinance disposal is the reduced risk to humans Currently EOD robots are able to traverse a variety of terrain collect and destroy certain explosives and provide improved reconnaissance capabilities to law enforcement and military agencies Although far from perfected these robots are saving lives by finding and disposing of explosives without the need for direct human contact In a press conference in Washington D C in April of 2004 Cliff Hudson the coordinator of the Joint Robotics Program of the U S Department of Defense stated that The bad news is l
64. is used on both sides to determine how to process each packet Next comes the number of devices and although this has different meanings for some of the packets it always tells the system how many different sets of bytes are about to be sent One set of bytes is usually two such as a SET packet where there s a channel and a value being sent for each set or three bytes per set like when the MOVE packet is sending PWMs In the case of MOVE one byte is used to designate the motor ID that is being set another byte to denote the direction a positive or negative voltage and a final byte to represent the duty cycle requested when forming and sending the PWM signal VI Controller Design A Introduction The basis for the design of the control system used for the project was created in an iterative process This was due to the fact that the only form of sensor return obtained from the arm consisted of position feedback as well as not being able to obtain the specifications of the motor used obtained through donation As a result of large masses inefficiencies and extraneous movement in the gearboxes the robots arm is a non linear system Because of this the onboard control system cannot use normal transfer functions tests for stability such as the Nyquist theorem or other standard control algorithms describing a linear system The robot is also not equipped with a way to determine the output torque of the motors to be fixed next i
65. l 19 4 2 Joint 2 Pot Ground D GND 46 Port 9 Big Claw Pot Power 5V 48 Port9 Big Claw Pot Signal amp 3 Big Claw Pot Ground D GND 42 Port9 Small Claw Extend Pot 5V 48 Port9 Power Small Claw Extend Pot 10 4 Signal Small Claw Extend Pot D GND 40 Port9 84 Ground Small Claw Close Pot Power 5V 48 Port9 Small Claw Close Pot Signal 14 12 5 Small Claw Close Pot D GND 38 Port9 Ground IR Sensor Power IR Sensor IR Sensor Signal IR Sensor 6 IR Sensor Ground IR Sensor Ultrasonic Sensor Power Ultrasonic Sensor Ultrasonic Sensor Signal Ultrasonic Sensor 7 Ultrasonic Sensor Ground Ultrasonic Sensor Pressure Sensor 1 Power Pressure Sensor 1 Pressure Sensor 1 Signal Pressure Sensor 1 8 Pressure Sensor 1 Ground Pressure Sensor 1 Pressure Sensor 2 Power Pressure Sensor 2 Pressure Sensor 2 Signal Pressure Sensor 2 9 Pressure Sensor 2 Ground Pressure Sensor 2 Digital Out Pin Port Pin of Destination Connector Joint 1 Down Limit Power Port5 DIOO 3 21 Joint 1 Down Limit Input Port5 DIOI 5 22 Joint 1 Up Limit Power Port5 DIO2 7 23 Joint 1 Up Limit Input Port5 DIO3 9 24 Joint 2 Down Limit Power Port5 DIO4 11 25 Joint 2 Down Limit Input Port5 DIOS 13 26 Joint 22 Up Limit Power Port5 DIO6 15 27 Joint 2 Up Limit Input Port5 DIO7 17 28 Wrist CW Limit Power Port5 DIOS 19 29
66. l Design Specifications Specification Result The arm must be able to approach target Two approach vectors from at least two position vectors possible The arm must be capable of lifting a 5 Ib load with arm at full extension Tested with 5Ib load The robot must provide user with real time Potentiometer feedback position data for each arm link visible on UI The outer gripper must supply minimum of Outer gripper strength of 40 Ib clamp force 47 lbs The gripper must have an emergency Easy to remove cotter 67 feature enabling the release of objects without power pins The inner gripper must be capable of gripping small objects such as wires and blasting caps Tested on circuit boards and wires The inner gripper must exert a minimum clamp force of 5 Ib Inner gripper strength of 6 lbs The robot must have active and passive emergency fail safes Software safeties limit switches emergency stop The robot must fit within a 60 x 36 x 48 box in the stowed configuration AEK R The robot must weigh less than 350 16 312 Ibs The robot must have onboard power Two Lead Acid 12Vdc Batteries The robot must reach a minimum ground speed of four miles per hour Max speed of 6 75 mph The robot must return visual feedback to Three streaming video the user interface from onboard cameras feeds The robot must have intuitive operation Xbo
67. law The third section of the controls is for attachable tools such as disrupter The advantage of this control system is that it allows control of each possible action of the robot Figure 4 Andros UI Display Screen The Talon control system is very similar to that of the Andros robot and can be seen in Figure 5 The self contained unit is opened like a briefcase to reveal a panel of switches and dials and a display monitor The controller contains a microphone and speaker to allow verbal communication through the robot Although this control system provides several different modes and controls it is not intuitive for first time users o Figure 5 The Talon Controller Figure 6 The Andros Controller IRobot s PackBot is sold with a control unit that consists of a standard computer as well as a game controller The controller uses a program that displays different camera views and includes a virtual 3 D model of the robot The program also displays the battery power as well as the strength of the communications signal This control system of this robot has the advantage that the user can easily tell the position of the robot without having to resort to using the cameras or guessing as is necessary with many of the other robots With this model the user can avoid running the arm of the robot into other sections of the robot This is much more difficult to do by using the cameras There are a number of program languages
68. llowing them to perform an increased range of tasks Some robots incorporate longer arms with increased degrees of freedom for improved dexterity and reach different gripper designs for improved manipulation and better cameras for improved visual awareness Although much progress has been made in advancing the capabilities of EOD robots there is still much work to be done Most robots are unable to disarm detonators primary explosives that trigger larger secondary explosives due to lack of dexterity and the need for opposable motion Control systems are often confusing and require lengthy training sessions before the operator can even move the robot Furthermore the sensor feedback from existing robots is severely lacking or nonexistent making it extremely difficult for the operator to perform desired tasks The goal of this project 15 to design and prototype a cost effective bomb disposal robot with improved functionality dexterity and situational awareness in order to reduce the need for placing explosive ordnance technicians in harm s way Some of the key areas that will be focused on in this prototype include a decreased production cost improved sensor package more dexterous gripper and more intuitive control systems Background EOD robots come in a variety of shapes and sizes with a wide range of available features Each system may vary in the mechanical design communication and control systems This section aims to outline th
69. locity Controller As seen in Figure 46 the velocity controller was implemented but quickly becomes saturated This leads to a constant overshoot that cannot be fixed by gain tuning Again the system delay in the response in noted as the desired motor output and velocity output is consistently saturated 63 This leads to very undesirable spikes in output producing violent motions in the arm Despite tuning the both loops to the robot arm the correct parameters are again dependent on the position of the arm as well although much less than iteration 1 E Iteration 4 Position and Velocity Control with slew rate added The last iteration adds a slew rate to the existing position and velocity cascaded control loops This is designed to prevent the robot from bouncing back and forth between its limits of output at various positions The reason that these cannot be auto tuned out is because of the changing torque exerted on the joint Slew rate 15 the rate of change in a process variable usually designated as the variable divided by time A slew rate limiter effectively limits how fast a rate of change can be similar to limiting the acceleration on a car to slow the rate of change in velocity The output of the PID loops is now given to this slew rate limiter allowing for control of how fast the output can switch between its limits Also noted is the addition of the safety system before the final output referencing the onboard
70. miting factor The more common rechargeable batteries that are usually considered on a smaller scale are Lithium Ion cells These are in many portable devices including everything from cell phones to MP3 players GPS devices and notebook computers A Lithium Ion battery is an optional add on to QinetiQ s TALON which increases the operating time by 4 5 hours more than doubling it G Summary The background research discussed in this chapter was important in understanding what has already been done in related fields and on existing EOD robot platforms Furthermore it explored several options for the hardware and software design highlighting some of the important advantages of different options 32 Methodology The methodology chapter discusses the approach taken in the design of the robot It defines the task specifications and the design process used to carry the design from preliminary sketches through to a finished prototype From this point on all material will be in reference to the prototype that the team developed and not to theoretical or existing robot systems 1 Design Specifications It is important to define a list of specifications that can be used to guide the design A detailed list of performance specifications as shown below helps to identify key goals of the final product The arm must be able to approach target from at least two position vectors e The arm must be capable of lifting a 5 Ib load with a
71. mum throughput of 300 Kbps would be required for a heavily encoded feed at 320x240 pixels 31 Since receiving video signals back from the robot requires significantly more bandwidth to transmit than the relatively miniscule operational data packets one option would be to separate the two This would allow a fiber optic based camera system to be used By deploying a thin extremely flexible tube of glass behind the robot as it travelled away from the control unit nearly perfect video quality can be achieved because encoding the raw feed is not necessary Encoding and extra compression to lower the video stream s bit rate would be neither used nor required to transmit the signal since the fiber optic cable is capable of providing a data throughput rate of many tens of terabits per second 13 far above the amount used in modern real time feeds However this means trailing a cable behind the robot which in turn would limit distance and usability If an emergency vehicle in the area were to accidentally drive over the cable the glass inside would shatter and the operator would completely lose visual communication Additionally because this method only deals with the visual aspect of the system it would need to be combined with another method for data communication too Instead of trailing a breakable fiber optic cable and worrying about maintaining contact a rugged copper based cable could be used to help withstand vehicles running over it
72. n For instance in a typical home or business network the user desires greater throughput speeds and has less concern for the maximum coverage area which never changes after the initial installation An 802 11g setup would work well for this due to a more efficient modulation technique OFDM that allows for a throughput data rate of up to 54 Mbps One down side of using this setup is that as the user moves farther away from the AP the throughput rate drops exponentially If this becomes an issue additional APs or repeaters can be installed at set distances to combat the problem From Computer Desktop Encyclopedia Reproduced with permission 2002 Intersil Corporation 802 114 802 119 11802115 0 55 6 9 11 12 18 24 36 48 54 Data Rates Mbps Figure 35 Wi Fi Rates 2 45 The robot s wireless requirements are drastically different from these conventional setups Here the top priority is to maximize distance with a single access point while still allowing enough bandwidth to view real time video streams For this reason the robot uses the 802 11b protocol that was introduced four years prior to 802 119 Version b uses a different modulation technique DSSS that spreads out each bit of data and sends it as multiple bits to help the receiver determine what is and isn t noise or interference This results in an even slower throughput data rate since the modulated signal has a theoretical maximum speed of 11 Mbps but it
73. n real time on a 2D graphical layout in the upper right quadrant This reference is placed adjacent to the primary video feed as both quadrants are equally important to a task such as moving the arm For example the operator can select the gripper camera to be the primary feed while still being able to quickly glance to the right in order to determine the link position 56 The lower right quadrant is dedicated to providing additional valuable feedback to an operator This data 15 received once the GUI sends a request for it after which it is processed scaled and displayed It allows the operator to see the values of every onboard sensor from the amount of force the main gripper is exerting to what percentage and distance that the outer gripper is extended Other crucial information available to an operator includes a measurement of the distance away from an object current battery levels and wireless signal strength The reason it s placed in the bottom right quadrant requiring the user to move their eyes the largest distance and focus on smaller text is because this information is not used nearly as often as any of the other quadrants The layout in its entirety aims to allow the operator to focus his or her attention mostly to one part of the screen the upper left but provides the additional three quadrants to be used as necessary Displaying Video Feeds The robot provides visual feedback to the operator using a series of three onboa
74. nclude a modular mount This mount would allow a disruptor light or other attachment to be used with the robot allowing an increase in the capabilities of the robot without dramatically changing the design of the robot Improving the dexterity of the inner gripper would improve the usability of the system This would allow the operator to move the inner gripper without moving the rest of the arm allowing more detailed work to be done by the gripper such as pulling out multiple wires from a single bomb What axis should be added could be determined by getting feedback from the users 74 IX Greater Impacts This project has the potential for vast social implications to bomb squads across the nation if the robot is developed further and made into a production model Currently an EOD technician is required to suit up and disarm an explosive with their own hands placing their life in immediate and direct danger This robot allows for an alternative approach that eliminates the need for any personnel to have close contact with a potentially explosive device whether it is to move it to a safer location or to neutralize the threat on the spot Other EOD robots do exist however their cost is a significant factor hindering the ability for smaller bomb squads and police forces to purchase them In many cases those departments that can afford a robot do not use it for small explosives in fear of destroying it For this reason the goal of having a prod
75. ng an actuator to push or pull a linkage system that opens the claw This system does not provide as much force but can save space in the design Table 1 Gripper Claw Comparison 2 ef 2 Caliber 12 Andros HD 1 Remotec Remotec N SET E S o un 8 o A C1 lt em un e 10 MURV 100 6 Vanguard Knight 29 RMI 9WT RMI 10F 22 EOD Partner oo gt gt l eS 8 8 E c gt One request from bomb technicians was to have gripper capable of disarming a blasting from explosive ordinance This action requires two claws one to hold the explosive ordinance package stationary and one to remove the blasting cap If only one claw is used to grab the blasting cap it is possible to drag the explosive device rather than removing the blasting cap Dual gripper robotic arms are currently not commercially available The Disruptor The detonator destruction 1s traditionally performed using a tool known as a disruptor Disrupters are commonly used to neutralize or disrupt a wide range of explosive devices by firing a high velocity slug of water at the threat 1 Disrupters can also be used destroy lock mechanisms allowing entry behind locked doors and inside vehicles Because the disrupter fires water there is a low probability that it will trigge
76. ng and assistance with complex manufacturing processes To the many professors who have offered advice and assistance and Tracey Coetzee for all of her purchasing and budget assistance Additional gratitude is extended toward the Robotics Engineering Program Electrical and Computer Engineering and Mechanical Engineering departments for their contributions to the project Finally a special thank you goes out to the project advisor Taskin Padir for providing useful insight and creative ideas throughout the design and manufacturing processes 76 XIII References 1 2 3 4 5 6 7 8 9 10 11 12 20mm Recoilless MK111 EOD Tools Waterjet Disrupters and Forced Entry Tools 2006 Web lt http www proparms com site product_9 html gt 802 11 News and Other Resources Technology News Analysis Comments and Product Reviews for IT Professionals CBS Interactive 2011 Web 25 Apr 2011 lt http www zdnet com topics 802 11 gt Ames Ben Makers of Ground Robots Ask for Better Sensors and Communication Military amp Aerospace Electronics 1 July 2004 Web 21 Apr 2011 lt http www militaryaerospace com index display article display 208448 articles military aerospace electronics volume 15 issue 7 electro optics supplement makers of ground robots ask for better sensors and communication links html gt Astronomy Tips for Meade s Autostar LXD 75 and LX200 Astronomy amp
77. ng application this H bridge can change its transistor output at a rate of up to 10 KHz 19 N 4 N Ae motor B N N GND Figure 13 H Bridge Circuit 11 Several motor controllers were researched as each offers a unique combination of features A summary of this research can be seen in Table 3 1 The 15A Cytron Figure 14 is a brushed DC motor controller The controller is capable of running a continuous 15A through the motor with 24V operation The motor controller comes configured for 12v operation and comes with a rotary encoder port along with a selectable power source The control method for this motor controller is PWM and it costs 49 Figure 14 Cytron Motor Controller 5 2 The Sabertooth 2X10 Figure 15 motor controller is a dual output motor controller providing 8A continuous and 15A peaks per channel It comes equipped with thermal and overcurrent protection and has three different input modes including direction via analog voltage RC PWM standard and RS232 The cost for this motor controller is 79 20 1 Figure 15 Sabertooth Motor Controller 7 The SyRen Figure 16 is a single channel 24V 25A continuous 45A peak motor controller designed for medium to heavy robotic applications It comes equipped with a regenerative system to recover normally lost energy in rapid accelerations The input methods allowed for this controller
78. nter The onboard cameras are also included in the sensor suite The robot provides visual feedback to the operator using a series of three onboard cameras that can be easily cycled through in the graphical user interface GUI The first is an AXIS 214 Pan Tilt Zoom PTZ camera featuring an 18x optical zoom 360 degrees of rotation and 180 degrees of tilt This camera is mounted five feet above the base of the robot to provide a clear view of the robot and its surroundings as well as an improved perspective for long range viewing Other features include auto focusing and auto IR filter control that allows clear images even in near total darkness requiring only 0 005 lux a typical point and shoot camera might require one or two lux of ambient light In order to provide a wide viewing angle for driving forwards the AXIS 212 PTZ model was chosen as the drive camera Unlike most PTZ cameras this has no moving parts and therefore zooming panning or tilting can be accomplished instantly The primary benefit of this model is that it has a 140 degree viewing angle when zoomed out greatly improving the operator s ability to see what types of objects lay ahead The third and final camera being used is an AXIS M1011 which features a much smaller physical form factor and like all the others a high resolution color image It has no special PTZ 42 functionality but that isn t required since this camera is mounted near the end of the gripper to
79. o be monitored A single PTZ camera with 360 degrees of rotation and 180 degrees of tilt can easily replace several fixed cameras if installed in an appropriate location Many of the PTZ cameras on the market have an exceptionally powerful optical zoom ranging anywhere from 12x to 35x and the 35x camera boasts the ability to easily read a license plate from 160 meters away An example of a PTZ camera with high optical zoom is shown in Figure 26 Usually PTZ cameras have moving mechanical parts and motors to allow their motion however there are also wide angle fish eye types of PTZ cameras in which no moving parts are used whatsoever An example of a fish eye camera is shown in Figure 27 This camera enables panning tilting and zooming features using a 140 degree super wide angle lens to display an overall view that the user can then pan or tilt to any part of zooming up to 3x without losing any image quality all instantaneously since nothing needs to move or refocus physically 5 Batteries To supply power to the onboard computer the communication system and every actuator the batteries need to be powerful enough to handle and sustain the maximum possible loads at any given time There are four common types of batteries used in mobile applications and depending on a system s requirements there is usually one type that stands out as the better choice 31 The most common heavy duty battery that was researched is the Sealed Lead Ac
80. of the resulting system also did not settle and encountered some of the same problems as the first iteration PID loop The robot arm would continue to overcompensate and overshoot the target because the full dynamics of the arm are too complicated to be described by a linear function Although this process helped it was inadequate to compensate for all the variables of the heavy arm that doesn t exhibit linear behavior D Iteration 3 Position and Velocity Control The control system of the robot could not be adequately described by a single linear equation To solve this problem a velocity controller was implemented on the premise of focusing on controlling just the velocity of the arm which would then be controlled by a position setting cascaded PID loop In order to implement a velocity controller a velocity must first be calculated Since the arm position feedback is entirely based on potentiometer readings the velocity must be calculated with that by the change in position over change in time 62 Figure 45 Cascaded Control Loop As shown in Figure 45 the inner control loops yellow input is given by the outer control loops output green In this case the inner loop 15 the velocity controller while the outer loop is the position controller The response of the system implemented above is shown below actual test on robot not a simulation BREER Z Figure 46 Saturated Ve
81. on 2 Standard PID Loop and Experimental System Model To solve the problems caused by mechanical factors resulting in the non settling system a rough system model was implemented Normally a Lagrange equation as previously derived would be applied to find the torque needed for each respective position for proper motion However since there is no way of determining the actual torque or current output in the current iteration of the robot a different solution was devised The method required modeling the arm as a single point mass dependent on the joint angles Because the mass of the arms is known this can be easily accomplished Next various motor outputs were sampled at different point mass intervals to gain a sampling of what motor power was need to compensate the gravity of the various arm point masses Lastly a 61 linearization was applied to form a simple model that allowed the rough system dynamics to be applied to the output cof 56 1 cof 228 T 1 20 length of link 1 l 27 length of link 2 T 0 4548 offsets for conversion sensor to angle 2461 0 26 slope for conversion senor to angle 0 25 8 13 offset xposition to pwm signal T 825 slope xposition to pwm signal J Sensor input Figure 44 Linearization for Dynamic Model of Robot Arm The equation shown in Figure 44 was then added to a PID loop to compensate for the error The response
82. on i fs a safety system x gt Active das all Os 0 monitoring 9 acceptable safety syste TL SS Usersafety Has the user _ 4 system iggered a safety _ P requeste 2 gt Service m Figure 37 Safety System Diagram The second safety system is a set of underlying safety variables running through the entire control system right down to the output lines on the controller Should any of the sub functions trigger this systems a corresponding safety will enable causing a subsystem shutdown while notifying the operator Should the error be designated serious enough it will also push the 49 entire robot into standby These safeties can be triggered by the controlling robot the sbRIO itself should it detect a fault condition or by pressuring the emergency stop placed on the robot The most active safety system is the monitor onboard the sbRIO This program watches the inputs from the sensors and actively detects and prevents failures This can include everything from accident and sudden input defects to a joint by joint position feedback loop ensuring that all feedback is within normal parameters Each monitor is fed by two separate sensors limit switches and potentiometers allowing for a redundant system Lastly because of all the potential energy contained in the disruptor it also has its own private safety loop This prevents any accident firings hardware
83. on to objects Finally modifications to the base have been made allowing mounting for all onboard electronics and wiring 69 User Interface The feeds from all three cameras are visible to the operator at any given time through the GUI which is best described by dividing it into four quadrants There is one main camera that is displayed in full size in the upper left quadrant to provide the user with a high resolution stream from the camera currently showing the most important view The two remaining camera feeds are displayed in reduced size in the lower left quadrant The three camera feeds can be easily cycled through using the controller In addition a visual representation of the robot arm is presented on the upper right quadrant of the GUI to provide feedback to the user on the position and orientation of the robot arm for an intuitive operation Finally the lower right quadrant incorporates additional control features and useful sensor feedback The layout of the robot GUI is shown in Figure 41 An open source library VLCJ is used for embedding these video streams into the Java controller GUI most efficiently This Java library acts as an interface between the VideoLan Media Player system level libraries to provide an interface to reliably connect to network streams with its own integrated extensive codec pack to allow for streams of any encoding method Each of the three cameras has unique specifications and can be u
84. osing the units in the field And the good news is losing the units in the field Every one lost is a soldier s life saved 2 Some of the drawbacks to using robotic systems for these missions are the difficult and complex control systems lack of dexterity and lack of sensory feedback Additionally the high to small law enforcement divisions with limited budgets EOD Figure 1 Blast Suit cost of these systems greatly limits their availability especially robots generally cost upwards of 250 000 depending on size mission capabilities and available tools Since bomb technicians have a higher success rate than robots due to increased dexterity visual awareness and the ability to make quick movements and adjustments many bomb crews still prefer to send in a human technician for smaller explosives in order to protect their investment from being destroyed by a small explosive As a result bomb technicians are frequently placed in harm s way to perform missions that could be neutralized by robots Despite the cost bomb disposal robots continue to sell to both military and law enforcement agencies because of their invaluable role in threat detection and neutralization On April 12 2011 iRobot Corporation of Bedford Massachusetts signed a 230 1 million contract with the U S Navy to provide them with EOD robots 16 The functionality of existing robotic systems has continuously improved over the past decade a
85. ot Figure 39 Labview programming The final output of the system was given by the output of the velocity controller after it put through a slew rate limiter This final output is sent to the motor controllers 52 Programming the Controller Unit The GUI for the controller unit is programmed in Java but it is only usable on a Microsoft Windows environment because of driver limitations at the time of development This section covers the main aspects of the GUI and explains how the larger tasks are accomplished like integrating the controller and camera feeds into the GUI independent of external parameters such as different codecs on the video streams An overall layout is explained and shown how it s intuitive and easy to use relative to some of the others on the market Finally the inner workings of the GUI are described down to the methods of sharing data between all of the classes of reliably since each thread is running on its own relative time and how the packets are formed before being sent out Controller Software A specification for the project was a low learning curve and although the time and resources available didn t allow for the calculation of the actual time the controls take to master it is confirmed that they are intuitive This is due to the setup being somewhat similar to most video games If the user has any experience playing on gaming consoles it should be easy to pick up a controller and figure i
86. ous gripper design was coupled with an easy to use graphic user interface and control system to provide EOD technicians with advanced explosive disarmament capabilities The key advantage of the gripper system is the ability to remove detonators from explosive ordinance without the need for direct human contact The visual and sensor feedback from the robot aids the operator in threat detection and manipulation and can be done from a safe range Finally the production cost of the robot including all systems that were donated or otherwise purchased is less than eight thousand dollars When compared to the cost of commercially available robots even if the cost is doubled in the finalization of the design a significant cost reduction can be seen greatly increasing the accessibility of the robot Though the completed robot is only a prototype there are several key features that with further development will increase the efficiency and abilities of bomb disposal units XI Acknowledgements A special thanks to our project sponsors including National Instruments for donating an SbRIO board Axis Communications for camera donations and The Wheel Chair Recycler for the wheelchair base donation Also to the many people who have aided this project including Toby Bergstrom Adam Sears and Neil Whitehouse for their assistance in the machine shop To Anthony Begins Michael Fagan the Sabertooth MQP team and Corey Stevens for their help with trouble shooti
87. oving the detonator The robot s gripper is specifically designed to allow for detonator removal A small three clawed inner gripper as shown in Figure 30 is controlled using a series of linear actuators a small 4016 actuator controls the opening and closing of the inner gripper while a larger 1501b actuator provides twelve inches of travel along the axis of the arm The gripper is able to move from its closed position to fully open with less than 50mm of actuator travel minimizing the space requirements needed for in the small actuator The inner gripper contains three prongs to allow it to grasp a wider range of objects 38 Figure 30 Inner Gripper Design Shown with Closed Half and Full Open Configurations The inner gripper was rapid prototyped to catch potential problems before manufacturing the final gripper One of the primary lessons learned from the rapid prototype model is the importance of tolerance The fingers of the prototype did not align properly and there was a great deal of slop in the joints The tolerance values were tightened in the final design to limit slop and assure precise alignment of fingers Another issue discovered in the prototype was that the shape of the fingers caused a gap to form when the claw was fully closed The final design was modified from a square profile to a rounded profile to allow complete closure of the gripper The large outer gripper shown in Figure 31 provides the ability to lift drag
88. p to 16 PWM outputs including four fast outputs Additionally it contains a backup 27 battery feature to allow for continued operation of the robot The data communication of this controller is high speed serial communication which would require a conversion to Ethernet The controller is programmed in C and costs 459 USD 4 Cameras The vision system of the robot is one of the most crucial because it allows an operator to control and react to anything in real time There are several different types of camera systems that could be used for this purpose and each has its own advantages and disadvantages Depending on what types of cameras are used the video signals should all be converted to a common type to facilitate transmitting the live streams to the operator In recent years digital consumer cameras have become extremely affordable and dozens of companies compete to provide high quality products that boast more and more features in each successive model while still keeping the cost low Although these point and shoot cameras weren t designed for continuous live streaming it s quite possible to use one as such Most models come with a video out port that clones the signal going to the LCD screen and outputs it as an analog composite video signal The purpose of this is to add the ability to share pictures and videos with others by plugging the camera directly into a TV or projector By placing the camera in capture mode instead of vie
89. r the explosive device to explode Recoilless disrupters are commercially available and provide an effective means to reduce wear on the robot arm The robot design incorporates a mount for the 98 percent recoilless Proparms 20mm 111 disrupter 1 Figure 8 shows iRobot s Packbot firing a disruptor at a target 21 11 Figure 8 iRobot s Packbot Fires a Disruptor 21 Base A mobile base is an important component of EOD robots The primary purpose of a base is to deliver the robot to the target As with the arm and gripper specific applications determine what the base looks like To accomplish this task the base must be able to maneuver the terrain required by the mission The key features that allow a robot to traverse different terrain include tracks wheels and flippers Tracked bases have several advantages when navigating through unstable rough terrain and wheeled vehicles provide higher speeds and lower cost for flat surface missions Tracks also allow some robots to climb stairs depending on the robot design Figure 9 compares tracked and wheeled vehicles based on the required operational environment such as terrain profile and required speed and mobility vehicle specification such as gross vehicle weight GVW and payload and economic issues related to operation Because of the multipurpose nature of EOD robots tracks are often used to allow the robot to function in even the most extreme environmental conditions Flippers are
90. rd cameras that can easily be cycled through In order to display the feeds irrelevant of the stream s encoding technique the GUI uses a public Java library VLCJ that contains methods to access the local VideoLAN Media Player Client VLC library on the machine This bridges the gap between low level C code to access core system functions and feed processing as it essentially integrates instances of VLC within the Java Swing environment painting each on a separate extension of the JCanvas class part of Swing This method was chosen largely due to codec versatility since VLC is well known as a cross platform media player capable of playing almost any form of media without any additional external codecs installed Threads In order to have multiple things happening at once without freezing the GUI or otherwise preventing it from updating a handful of threads are used Upon initialization the first thread created is an instance of the Listener class to continually listen for an incoming packet on the port used for communication between the robot and GUI When a packet arrives it s passed to the PacketHandler class which determines what type of packet just arrived If it is from the robot and it is a sensor value the appropriate method is called to scale the value and update the GUI This thread is also useful for confirming that a packet was sent out successfully since the User Datagram Protocol UDP is being used to send packets to all add
91. resses on the subnet This 57 means that the GUI receives them and quickly realizes that the packet source is the controller unit resulting in simply displaying the packet data to the console and proceeding The next thread to be initialized is the XboxController Similar to the PacketListener there exists a XboxHandler purely for the purpose of updating the CurrentValues class instance which has all of the controller and GUT s settings stored to share between classes since its methods and variables are synchronized with all of the threads The XboxController thread s primary purpose is to poll the Xbox 360 controller s event queue every 20ms to see if there are any changes in analog or digital buttons This means that it doesn t have to check while the user is doing something since the events are all stored until they are read and completely processed The thread also handles control of which buttons call which methods in the GUI or update certain values in the CurrentValues class Another important manually created thread is the SendControls instance This is ultimately what sends commands every 100 milliseconds to update motor speeds camera movements and any other analog values It computes the arcade driving PWM signals and determines the direction every motor is going It relies heavily on the synchronized methods from the CurrentValues class to provide reliable feedback regarding which mode is active and therefore which motors to set
92. rm at full extension e The robot must provide user with real time position data for each arm link e The outer gripper must supply minimum of 40 Ib clamp force e The gripper must have an emergency feature enabling the release of objects without power e The inner gripper must be capable of gripping small objects such as wires and blasting caps e The inner gripper must exert a minimum clamp force of 5 Ib The robot must have active and passive emergency fail safes The robot must fit within a 5 x 3 x 4 box in the stowed configuration The robot must weigh less than 350 lbs e The robot must have onboard power e The robot must reach a minimum ground speed of four miles per hour e The robot must return visual feedback to the user interface from onboard cameras e The robot must have intuitive operation through sensor feedback and control methods e The robot must communicate wirelessly with a minimum range of 150 meters line of sight e The robot must contain modular components e The robot must have a production cost less than 10 000 2 Modeling and Analysis This is where the design work begins This involves creating sketches of components to understand how features will work modeling the 33 ideas in a CAD system and performing a range of dynamic and kinematic analyses to analyze the design The majority of modeling was focused on the arm design limiting the time spent on base designs Additionally
93. rop Grumman Information Systems Web 21 Apr 2011 http www is northropgrumman com by solution remote platforms product ind ex html gt Remote Mobile Investigator RMI Pedsco Canada Ltd Over 30 Years in the Robotics Industry Web 21 Apr 2011 lt http www pedsco com products php gt Robot Power Products Simple H Single H bridge Robot Power Web 21 Apr 2011 lt http www robotpower com products simple h_info html gt Robot Speed Controllers ESC amp R C Electronic Switch Interfaces The Robot MarketPlace amp Team Nightmare BattleBots amp Combat Robotics Information Web 21 Apr 2011 lt http www robotmarketplace com marketplace_speedcontrollers html gt R O V Technologies Inc Vehicles R O V Technologies Inc Home Web 21 Apr 2011 lt http www rovtech com Vehicles Index html gt Tinkering with Electronics Web 21 Apr 2011 lt http real2electronics blogspot com gt QinetiQ The Soldier s Choice TALON Huntsville AL Online Vanguard Digital Vanguard Data Sheet Ogdensburg NY Online WM Robots Robot Brochure 2006 Colomar PA Online Z Patrikakis N Papaoulakis Stefanoudaki M S Nunes Streaming content wars Download and play strikes back presented at the Personalization in Media Delivery Platforms Workshop 218 226 Venice Italy 2009 79 XIV APPENDICES
94. rring the information into usable Labview commands Using the streamline packet protocol outlined in the communication section the robot takes the incoming packet as a string and parses it into sections A pass fail test determines if the packet was indeed destined for the robot with the following information determining if the command is setting a motor changing a safety packet or asking for information from the robot This entire process is done at a rate of 100Hz allowing for a five millisecond timeout for UDP packet arrival 48 Safety System As a result of the inherent dangers in a large heavy robot the bomb disposal unit comes equipped with several redundant safety systems designed to prevent damage to both the robot and the personnel in the surrounding area shown in Figure 37 The first safety feature is a system that automatically and carefully turns the robot s systems on standby if the connection to the host is lost This is determined through a loss of valid packets for longer than 250 milliseconds In order for this safety to trigger the robot must have completely lost two packets in a row a packet is set out every 100 milliseconds In order to prevent the robot from getting stuck some place however a simple re enable of the systems safeties when the robot is in range will resume operation This automatic system prevents run away conditions that can lead to injury Action packet from host arrives Connecti
95. s still sufficient for three encoded video streams and control packets Figure 35 shows the implementation of 802 11g and 802 11b both forced to use DSSS The latter was chosen because 802 11g typically uses OFDM instead of DSSS and a more constant and predictable throughput rate is desired for this application One benefit of this protocol is a significantly extended range since instead of an exponential drop off the data rate decreases linearly as the distance increases Additionally unlike OFDM DSSS modulation is not susceptible to the Doppler Effect and is therefore better suited for a quick moving mobile application The router in use comes with the standard factory firmware but this doesn t allow the user to change many low level hardware settings that can greatly improve performance The firmware itself is installed on a flash memory chip that is set to a read only mode within seconds of turning on the device right after the settings are written to it from the EEPROM These first few seconds where the flash memory chip is still writable can be extended indefinitely by initializing a write to the chip thus interrupting the normal starting procedure With the flash memory now over writable customized third party firmware can be uploaded and set to automatically load in place of the factory software Since the reset button on these devices only erases the EEPROM the change is permanent until the chip is re flashed to something else Th
96. safety Additionally three cameras are positioned in strategic locations in order to assist an operator in accomplishing the task at hand Both the central processing board and cameras are plugged directly into a wireless router which is used to communicate all of this necessary information back to the controller unit An overview of the robot system can be seen in Figure 28 is 360 Boom Camera Gripper Camera 3DOFArm Range Sensers Figure 28 Final Robot Design Overview 35 Arm Design The robot s manipulator arm is designed for multi mission use providing a long reach and good mobility The arm is long enough to be able to reach inside vehicle windows while mobile enough to manipulate a target from a variety of different approach vectors The mobility of the arm can be defined by the Kutzbach Equation 3 to have three degrees of freedom One of the advantages of having a three DOF arm mounted on a mobile base is the ability to approach a target from multiple directions An important application of this can be seen in positioning the disruptor for an optimal firing position The three degrees of freedom are controlled using methods shown in Table 4 Table 4 Arm Drive Information Joint Drive Method Rotation 1 Worm gear gearbox 200 2 Chain drive through worm gear gearbox 270 3 Planetary Gearbox 360 The arm requires drive motors capable of overcoming the force due to the
97. sed depending on the task being performed The cam is able to rotate 360 degrees and tilt 180 degrees allowing it to see anything below the height at which it is mounted It can also be used to zoom in to distant objects since it features a lens capable of 18x optical zoom and 12x digital zoom providing a combined image amplification of 216x second camera is mounted low and attached to the front of the robot This drive cam provides a 140 degree wide angle view and has motionless digital PTZ functionality built in allowing a 3x zoom if necessary The final camera is mounted to the gripper and has a short focal length to assist the operator in grabbing on to objects When testing there was an experienced delay when processing the video feed With one camera the latency was only a tenth of a second but when all three cameras were linked the delay increased to about a half of a second This is likely due to the additional processing overhead that is required to process multiple feeds 70 To allow the user to control the robot through the GUI a standard Xbox 360 gamepad is used The control layout can be seen in Figure 40 and can be easily changed in the code to accommodate other preferences Nearly all of the buttons on the controller are implemented and only some of the analog inputs are used for multiple tasks lowering the overall learning curve for the device D Wireless Capabilities The wireless distance test r
98. t out The Xbox 360 controller was chosen for its extensive mapping capability of ten digital buttons and five separate axes and most importantly its popularity Java is infamous for problems interfacing with external hardware The public third party library JInput exists to bridge this gap between Java and controllers of all types In this application the Xbox 360 controller s layout defaults to the controls seen in Figure 40 but these are easily changed in the code since every button or axis is assigned in one spot Every function can be assigned to a different button or joystick so long as analog inputs and digital inputs aren t swapped which the code doesn t allow for as is anyway 53 Text color indicates button functionality for diferent modes Black Works in all modes Blue Camera mode for PTZ capable devices only Red Arm Gripper mode only Switch between Enable Disable modes obot control Arcade style driving control 9 Q e Switch between inner outer grippers Move active arm link 16 Rotate outer gripper d retract inner claw main camera feed Opens selected Closes selected gripper gripper Zoom out on main Pei Zoom in on main camera feed camera feed Select active n Cycle through main arm link camera feeds Figure 40 Gamepad Control Pin out There are a couple different modes the GUI can be in but regardless of the mode som
99. teration Therefore it is also unable to be controlled using the standard Lagrange equations derived in mechanical design section B Iteration 1 Standard PID Loop The first iteration of the control system consisted of a standard PID loop with anti integral windup The PID loop is given in Figure 42 59 u t MV t K e t dr Figure 42 PID Shown above are the three terms of the PID controller These terms are the proportional term Kp the integral term Ki and the derivative term Kd The proportional term is responsible for giving an output based directly the error that exists The integral term 15 designed to correct steady state error that is accumulated over time Lastly the derivative term limits the transient response magnitude allowing for a smooth transition with a smaller settling time The e t terms are the derived error terms calculated by subtracting the set point from the actual position The final output is shown as u t which is also broken down into the mass M times the velocity V t This PID loop also has an anti windup term for the integral term separate from the equation Integral windup is a large factor that builds up during the transient period of the system causing offsets when the system nears its set point The anti windup is used to prevent this large amount of error accumulating during the transient response while still taking advantage of steady
100. uction cost of less than 10 000 was set It is important to note that the robot designed and built over the course of this project is only a prototype and should not be used to disarm actual explosive ordnances After further development on a production model an increased number of safety features and extensive testing it would be viable for a trained EOD technician to use the robot Until that point the team cannot suggest its use in anything other than safe testing environments Akin to most of the EOD robots on the market batteries power the electrical system used by all motors and devices The two deep cycle lead acid batteries provide a quiet reliable and predictable source of energy since the voltage levels are always available to the operator The batteries will need to be replaced after an estimated one to three years of nearly every day use according to the manufacture for the wheelchair base alone taking into account eight hour days of completely discharging the batteries At this point the battery cores will be recycled since there are laws in place governing this practice This ensures the environment will not be affected by the use or disposal of the lead acid batteries used and that no carbon footprint exists from the direct use of the robot The overall sustainability is therefore quite high and since a set of batteries costs only 140 the cost of operation is incredibly low 75 X Conclusions In this work a dexter
101. uded to prevent overloading the processor with too many I O requests This board comes equipped with basic shock and drop resistance and is certified to operate in extreme temperatures up to 138F Communication with this board is performed using the built in Ethernet port and four serial ports There are 110 digital I O ports and 32 analog inputs controlled by the FPGA If more ports are ever required a different unit will be required Axon IT Another possible solution is the Axon II robot controller This heavy duty motor controller is a small streamlined controller capable of 58 different I O including 16 analog to digital converters as shown in Figure 24 26 Figure 24 Axon II 6 This board comes equipped with over 25 servo outputs as well as eight external interrupts The onboard software in C is completely open source allowing for extensive library use The board is also capable of outputting over 15 PWM channels Lastly the communications system is either UART or USB requiring an Ethernet adapter The cost of this controller is 219 USD FRC Controller Another robot controller under consideration is the FRC controller The controller is sturdy and capable of 32 separate I O including 16 10 bit analog inputs Shown in Figure 25 MICROCHIP Ir Zontrol x H 2 8 d Figure 25 FRC Controller 19 This chip uses the PICmicro processor allowing for high speed operation The controller allows for u
102. umber of devices being requested or returned in this packet DEVICE ID 1B The device ID that a value has been requested from or returned for Packet data length 4 4 is minimum for sbRIO to receive the request for 6 is the minimum the sbRIO will send back MOVE Packet This packet travels only from the controller to the robot Sets PVMS Packet structure SOURCE 1B Will always be SOURCE CONTROL 1 ACTION 1B MOVE 77 decimal for NUMBER OF SETS 1B Number of devices being set CHAN 1B The channel or unique identifier to set a value for Denoted as in pinout DIRECTION 1B Either F dec 70 or R dec 82 87 VALUE 1B A value between 0 and 99 to send for power Packet data length 6B SET Packet This packet travels only from the controller to the robot Sets Relays Packet structure SOURCE 1B Will always be SOURCE CONTROL 1 ACTION 1B SET 83 decimal for S NUMBER OF DEVICES 1B The number of devices being requested or returned in this packet CHAN 1B The channel or unique identifier to set a relay 1 10 Denoted as on pinout VALUE 1B Value 0 off or 1 on Packet data length 5B SAFE EMERGECY Packet This packet travels only from the controller to the robot Sets Robot Safes Packet structure SOURCE 1B Will always be SOURCE CONTROL 1 ACTION 1B E 69 decimal for E NUMBER OF DEVICES 1B The number of devices being disabled enabled ITEM
103. user to send input to the program about how to drive and control the arm The program pulls up a control interface when it detects a robot on the network This control interface includes feedback about the status of the robot as well as information indicating what robot is connected The information displayed on the interface includes the battery voltage signal strength internal temperature and GPS location There is also a button to press to bring up the video feed form the robot s camera The advantage of this control system 15 that it uses a very similar control system to that used in a number of video games that the majority of solders have played The Andros robots use a custom made interface as shown in Figure 6 The interface consists of a control panel with a series of switches and knobs to control the different actions of the robot as well as a video screen to show the camera feedback The Andros robot has four onboard cameras yet only one feed can be seen at any given time see Figure 4 Next to the screen there are controls for the volume of a speaker on the robot and headphones attached to the UI The control panel is divided in to three sections The first section controls the different aspects of the cameras such as which camera is displayed the zoom focus and a variety of other controls The second section of the control panel controls the physical motions of the robot such as the position of the arm driving and control of the c
104. wing mode a real time view is sent out the same port in analog composite form This raw video signal isn t very usable without first processing it and converting it to a digital signal Many companies make a specialized piece of equipment called a Video Server that is able to take an analog video signal as an input and stream a digital signal over an Ethernet RJ 45 network cable with its own IP address The video codec compression rate frame rate and other settings can be set by the user to optimize the output to meet a required specification For a fraction of the cost this method allows a consumer grade video camera to effectively become a highly configurable network camera with autofocus optical and digital zoom and often at least an automatic neutral density filter to accommodate a bright sunny day or areas with lower light levels Additionally due to the lower cost and cheaper filters used in consumer grade cameras they are almost always more susceptible to infrared interference This means that they could be used in pitch black conditions with infrared spotlights as a light source which could be 28 useful in warzone conditions since this wavelength of light is invisible to the naked eye to continue to provide a high quality monochrome video feed There is only one reason to use the bulky setup of a camera with analog output combined with a video server to end up with the equivalent of a network camera and that reason is cost
105. wn in Equation 3 This equation was derived to describe the torques at each joint Because the wrist rotation does not move the location of the center mass of the arm it can be considered negligible in finding the torques for the first two joints 37 Equation 3 Arm Torque Equation 72 f Y f Y uf Y f amp m m A m m 1 1 2 m m 12113095 8 m m 1 1 m m 1 L cost 8 T f 2 2 2 L L eost 8 0 0 ww 5 4 1 4 amp m m 2 6 8 93 5 6 m m JgL cost 8j m tm L 2 cos 8 8 8 Y m m ja Z 1 Jeost 81 8 k m m L L L 81 sint 8 d 8 m L L cos 8 0 B Gripper Design The gripper is one of the novel features of the robot and is designed to allow access to the target as well as the ability to manipulate it One desired feature for a gripper is the capability to disarm a blasting cap also known as a detonator from explosive ordinance The blasting cap is a small charge that initially detonates triggering the larger explosive 6 To disarm this device with a robot two claws are required one to hold the explosive ordinance package stationary and one to grasp and pull out the blasting cap If only one claw is used to grab the blasting cap it is possible to drag the explosive device rather than rem
106. x 360 controller with through sensor feedback and control easy to use GUI methods displaying sensor feedback from the robot The robot must communicate wirelessly with a minimum range of 150 meters line of sight Max tested range of 170m with excellent signal strength The robot must contain modular components Standard hardware detachable boom The robot must have a production cost less than 10 000 Estimated production cost of 7000 00 Mechanical Systems Figure 49 Side View Figure 48 Front View The final robot is comprised of a mobile base supporting the robot arm and gripper all onboard sensors electrical hardware and wiring as shown in Figure 48 and Figure 49 The arm has been manufactured to the specifications defined in the final design The gripper system contains slight modifications from the final design The outer gripper claw has been manufactured by welding hollow box steel into the shape of the design rather than using machining or metal forming processes to create the part The reason for this change is twofold cost and weight A custom forged part or the high volume of steel required for machining the gripper claw would not only be costly but would greatly increase the weight at the end of the arm The fingers of the inner gripper have been coated with tool grip a sticky textured spray on coating that increased the friction of the gripper increasing its ability to hold

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