Remote Controlled Fetch Machine
Contents
1. and the possibility of having a color LCD screen Figure 1 Diagram showing horizontal swivel capability on the machine Left and diagram showing launch mechanism along with adjustable launch angle Right University of Florida EEL4924 Senior Design Spring 2011 4 Remote Controlled Fetch Machine Competing Products Commercial automatic fetch machines already exist Two such products are the GoDogGo G3 Fetch Machine and the Fetchtastic Automatic Fetch Machine for Dogs These products are similar in that they both accomplish the following e Throw atennis ball up to 25 30 feet e Automatically throw a ball if there is one present However these machines lack some key features of the Remote Controlled Fetch Machine Swivel position left and right Swivel trajectory up and down Distance control Wireless remote control Figure 2 Example of a competitive product Fetchtastic University of Florida EEL4924 Senior Design Spring 2011 5 Remote Controlled Fetch Machine Implementation Implementation began by selecting microprocessors for the remote and machine The MSP430F2272 was chosen for two reasons Its low power consumption made it a perfect fit for a handheld remote Also its PWM capabilities were robust and easy to configure for the machine s needs The Machine The main design focus of the machine was choosing the method in which the tennis balls would be thrown The two primary choices for implementing2. 45 90 Glue Epoxy 11 99 Servos 35 99 47 98 23 99x2 1 95x2 MOSFETs 3 90 12V Power 18 99 Suppl Tennis Balls 6 98 Color LCD 34 95 Machine PCB TOTAL COST 454 01 Table 2 Table of total costs University of Florida EEL4924 Senior Design Spring 2011 14 Remote Controlled Fetch Machine Gantt Chart X f AS x Y y S Y amp E V ES Y N oy ay Y on A ar N X N N N Na Preliminary Research F Design Phase a L L L Machine Design Remote Design Communications Design Machine Programming Remote Programming Testing and Debug E Board Design and Construction Machine Assembly Remote Assembly L Troubleshooting a Report and Presentation Figure 10 Gantt chart which details time management and usage for the project University of Florida EEL4924 Senior Design Spring 2011 15 Remote Controlled Fetch Machine Appendix Codes Below are the data codes used for communication between the remote and the machine Accelerometer Swivel Clockwise Counter Clockwise 0x5X Throw 0x75 Position 1 0x51 0 Full Right Position 2 0x52 Position 3 0x53 Position 4 0x54 Position 5 0x55 Level Position 6 0x56 Position 7 0x57 Position 8 0x58 Position9 0x59 135 Full Left Accelerometer Swivel Ramp U D 0x6X Position 1 0
3. codes can be found in the Appendix The byte is decoded and either a PWM signal is changed or a mode automatic manual or indoor outdoor is changed If the user chooses to throw a ball the machine enters a routine that changes the PWM signal of the speed controller and latch at certain time intervals in order to release the ball into the throwing mechanism Once the ball is thrown the latch returns to its closed positions and the motors are powered down If automatic mode is selected the MSP checks for a ball A force sensor was used to detect the presence of a ball The force sensor is a variable resistance that changes as force is applied The following circuit outputs a voltage between 0 and 3 3V which connects to the MSP430 ADC analog to digital converter where RM 1 5MQ University of Florida EEL4924 Senior Design Spring 2011 9 Remote Controlled Fetch Machine Figure 6 Force sensor circuit diagram If the voltage reaches a threshold of 1 6V then a ball is present If a ball is present the machine enters the throwing routine and then checks for data from the remote This process is repeated until manual mode is selected The program flow chart detailing this process is shown on the following page The Remote The block diagram below illustrates the fetch machine remote s architecture Four momentary push buttons xBee 1mW chip antenna MSP430f2272 16x2 monochrome ADXL335 analog LCD display accelerome
4. Machine Figure 9 Remote software flow chart University of Florida EEL4924 Senior Design Spring 2011 12 Remote Controlled Fetch Machine Project Responsibilities Component Brandon Grillo Fetch Machine Construction Servos Motors Force 100 0 Sensor Fetch Machine MSP Code 100 Remote Construction 40 60 Buttons LCD 0 100 Accelerometer Remote MSP Code 100 Table 1 Division of labor Overall the division of labor closely followed the assigned responsibility table User Manual 1 Turn on POWER for the machine as well as the remote via the power switch 2 Pressing the MODE button will select MANUAL or AUTOMATIC mode a MANUAL allows user control of the machine b AUTOMATIC launches balls at regular intervals until turned off 3 Pressing the DISTANCE button will select INDOOR or OUTDOOR a INDOOR selection sets launch distance to approximately 15 20 feet b OUTDOOR selection sets launch distance to approximately 30 40 feet 4 Pressing the SWIVEL button will allow for manual aiming of the machine a Tilting the remote horizontally or vertically will swivel the machine or adjust the launch angle respectively b SWIVEL stays on until the button is pressed again 5 Pressing the THROW button while in manual mode will launch a ball University of Florida EEL4924 Senior Design Spring 2011 13 Remote Controlled Fetch Machine Bill of Materials 10 22 95x2 Xbee RF chip
5. Remote Controlled Fetch Machine Final Design Report with Diagrams KEL4924 Senior Design 19 April 2011 Members James Su amp Brandon Grillo Project Abstract The Remote Controlled Fetch Machine is a device designed to reinvent the way owners can exercise and entertain their dogs It allows owners to play a game of fetch with their dog from a distance with the use of a handheld remote featuring an intuitive interface The handheld remote features an LCD screen and buttons to navigate an on screen menu These buttons are used to control the behavior of the machine Also the remote has an accelerometer which allows users to swivel the machine by tilting the remote left right or toward the user University of Florida EEL4924 Senior Design Spring 2011 2 Remote Controlled Fetch Machine Table of Contents Project Features pg 3 Competitive Products pg 4 Implementation pg 5 Project Architecture pg 7 Project Responsibilities pg 12 User Manual pg 12 Bill of Materials pg 13 Gantt Chart pg 14 Appendix pg 15 List of Tables and Figures Fig 1 Diagram of swivel and launch capabilities pg 3 Fig 2 Picture of competitive product pg 4 Fig 3 Machine design pg 5 Fig 4 Machine block diagram pg 7 Fig 5 Speed controller circuit diagram pg 8 Fig 6 Force sensor circuit diagram pg 9 Fig 7 Remote block diagram pg 9 Fig 8 Machine software flow chart pg 10 Fig 9 Remote software flow chart pg 11 Fig 10 Ga
6. mote For the remote the goal was to make the interface as simple and intuitive as possible We discussed various user interface methods and eventually narrowed it down to either a glove based control or a normal handheld remote control With the glove control we were going to implement various types of sensors including flex sensors touch sensors and various types of buttons while with the handheld remote we were only going to use momentary push buttons Ultimately we decided to go with the handheld remote design because it was simple effective and cost efficient In order to implement swivel control in the machine we decided to use a simple 3 axis analog accelerometer for tilt sensing in the remote By using an analog accelerometer we were able to use two of the eight analog to digital conversion pins on the MSP430 rather than take up one of the two USCI modules this provides flexibility when connecting additional peripherals In addition we had an analog accelerometer available so this helped us cut back on costs Next we had to decide on a wireless communication interface between the remote and the machine After weighing various options we decided to use xBee wireless transceivers because they had a suitable range sufficient data transfer rate and an intuitive setup One of the additional considerations for the project initially was to possibly include a camera of sorts on the machine that was capable of transmitting video data back t
7. ntt chart pg 14 Table 1 Division of labor pg 12 Table 2 Bill of materials costs pg 13 University of Florida EEL4924 Senior Design Spring 2011 3 Remote Controlled Fetch Machine Project Features The Remote Controlled Fetch Machine will be comprised of two major components a remote and a device that will throw a ball The throwing machine will have the following features Machine Ability to throw a miniature tennis ball The entire machine can swivel horizontally between 0 and 135 The ball can be thrown at an angle from 0 to 35 from the horizontal Sensor to detect the presence of a ball in the machine Automatic and Manual Modes that automatically throws a ball when it is retrieved without the user s command or throws a ball on command e Indoor and Outdoor Modes that changes the distance that the ball is thrown by adjusting motor speed e Large drop zone for retrieved tennis balls to be placed Remote Accelerometer for tilt sensing control A basic LCD Screen for a simple menu interface Interface buttons to select modes and menu items Both the machine and remote will include a transceiver to allow for RF communication The final design for the machine met and exceeded all of our initial design objectives Several features we have added which were not part of the original basic design include the ability to launch the ball at different speeds the ability to have varying launch angles
8. o the remote This would have required the use of a faster wireless system since the xBee data transmission rate would not have been sufficient In the end we decided to use the xBee modules and planned on switching to another faster wireless system if we had time to implement video transmission Having decided on our wireless system we then discussed display options For our purposes a 16x2 monochrome LCD display was enough to present the menu options and data sufficiently and was cost efficient as well However we decided to leave room for a possible upgrade to a 128x128 color LCD display time permitting For the remote casing we debated between building one out of wood and ordering a premade plastic or aluminum one online Because we had wood left over from the machine construction we decided to go with crafting the remote casing out of wood since it would save us some costs University of Florida EEL4924 Senior Design Spring 2011 7 Remote Controlled Fetch Machine Project Architecture The Remote Controlled Fetch Machine can be broken down into two projects the wireless remote and the fetch machine The Machine The architecture of the fetch machine is represented in the block diagram below Force Gersor I kBee p MSP430 Paas Tiis 27 Brushed DC Motor Tm E HEEE HG Servo TAi Lye Figure 4 Machine block diagram Functionality begins by initializing Timer A and B of the MSP430 t
9. o use its Pulse Width Modulation PWM capabilities Each servo requires a PWM signal to operate The pulse period for all servos is 20ms The duty cycle for all servos varies between 600ms and 2400ms Based on the duty cycle the servo will rotate to a position between 0 and 180 The motor speed controller also requires a PWM signal at the same frequency but its duty cycle ranges from 0 to 100 of the pulse period Once Timers A and B were initialized the duty cycles for their corresponding servos were set for their initial positions e The servo that swivels L R was centered e The servo that swivels U D was set to 0 ramp flat e The latch servo was set to a closed position e The speed controller was set to 0 speed The speed controller was designed using two IRF510 MOSFETs with a 12V PWM signal at the gates When 12V is applied to the gates current passes through the University of Florida EEL4924 Senior Design Spring 2011 8 Remote Controlled Fetch Machine MOSFETS from the battery through the motors By modulating the PWM duty cycle from 0 to 100 the DC motor speed is varied from 0 to 100 Two MOSFETS were chosen to conduct the high current demands of the motors Below is the speed controller design l IRF510 4 IRF510 12V PWM Signal Figure 5 Speed controller circuit diagram Once all initializations were made the MSP430 waits for a single byte of data from the remote via an Xbee RF chip The data
10. ter Figure 7 Remote block diagram Once the machine is powered on the LCD screen 1 0 pins for monochrome SPI for color analog accelerometer via the ADC on the MSP430 and xBee module via the UART on the MSP430 are initialized The software then polls the button switches constantly to see if the user has pressed any of them Once a button is pressed the MSP430 sends out the corresponding command code byte to the xBee and updates the menu on the LCD screen If the swivel button is pressed the MSP430 continuously reads in converts to digital and modifies through a linear equation two values one for the x axis and one for the y axis This value is then compared to a table of discrete value ranges Based on where each value falls the corresponding code containing the x and y positions of the accelerometer is sent out through the xBee Continuous position data transmission ends once swivel mode is turned off The program flow chart detailing this process is shown on page 11 University of Florida EEL4924 Senior Design Spring 2011 10 Remote Controlled Fetch Machine Fetch Machine Program Flow Chart am ra fa iwida r Thep Ahoi Pets t ode ede O aera dd Te Wia a hh TPI Tariyel Lif WE eg PA maed on LEETE aces idm flag 1 Charro mii accel pninoa kerel pirina Figure 8 Machine software flow chart University of Florida EEL4924 Senior Design Spring 2011 11 Remote Controlled Fetch
11. this were e Anarm that could launch the ball similar to a catapult e The ball is fed between two wheels spinning in opposite directions similar to a baseball pitching machine Ultimately we chose the second method because it required less mechanical design and would be capable of throwing the ball farther Our next major concern with the machine was how to construct it Although plastic or metal would make the machine more durable we chose to construct it out of wood We chose wood because metal and plastic are very expensive and difficult to use construction materials without the proper tools Using wood allowed us to easily construct and modify the machine design Finally we chose the electrical components that allowed us to achieve the machine s features All movement features of the machine could be accomplished with servos with appropriate torque for the feature it was implementing A high torque servo was installed on the bottom of the machine that would swivel it clockwise and counterclockwise A medium torque servo was used to control the elevation of the ramp A small micro servo was used to control the latch that released the balls into the throwing mechanism Lastly two 7 2V brushed DC motors were used with a one direction speed controller to implement the throwing mechanism Figure 3 Picture showing machine design University of Florida EEL4924 Senior Design Spring 2011 6 Remote Controlled Fetch Machine The Re
12. x61 0 Level Position 2 0x62 Position 3 0x63 Position 4 0x64 35 Tilted back Modes 0x4X Manual 0x44 Automatic 0x43 Indoor 0x42 Outdoor 0x41 University of Florida EEL4924 Senior Design Spring 2011 16 Remote Controlled Fetch Machine As an additional note due to size constraint issues and necessary component placements the PCB design for the remote control could not be milled in house since through hole plating is unavailable in house Below is the PCB design for the remote controlled as sent to Advanced Circuits LELI Pal
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