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Sergio Zapatel Interactive Ultrasonic Guided System

1. asking and reading the value of the low byte of the register I2CTWI_transmitByte LCD ADR 1 keypad_low byte I2CTWI_readByte LCD ADR now the two register are joined in one variable key pressed keypad _ low byte keypad high byte lt lt 8 switch key pressed to each key is assigned its numerical value and the ascii code that corresponds The value used in the switch structure is the value of the complete register case 0 key 12 break no pulsation 12 case 1 key 1 keychar 1 break 1 case 2 key 2 keychar 2 break 2 case 4 key 3 keychar 3 break 3 case 8 key 4 keychar 4 break 4 case 16 key 5 keychar 5 break 5 case 32 key 6 keychar 6 break 6 case 64 key 7 keychar 7 break 7 case 128 key 8 keychar 8 break 8 case 256 key 9 keychar 9 break 9 69 Interactive Ultrasonic Guided System case 512 key 10 keychar break 10 case 1024 key 0 keychar 0 break 0 case 2048 key 11 keychar break 11 while key pressed gt 0 this loop detects when the key has been released It goes out of the loop when the value of the register of the t keypad is 0 key pressed 0 uint8 t keypad_high byte uint8 t keypad_low byte I2CTWI_transmitByte LCD ADR 2 keypad register high byte keypad high byte I2CTWI readByte LCD ADR I2CTWI transmitByte LCD ADR 1
2. SERGIO ZAPATEL G20494156 E Z SELECT YOUR OPTION IN THE NEXT SCREEN E void main void Configure RP6 o initRobotBase initializa RP6 powerON configure I2C I2CTWI_initMaster 100 Select I2C bus operation frequency configure SRF O startStopwatch1 initialize stopwatch for function take_measure distance stop distance l Configure LCD init cursor I2CTWI transmit2Bytes LCD ADR 0 19 switch on backlight Intro screens write LCDCintroScreenl wait hash write LCDCintroScreen2 wait hash write LCDCintroScreen3 wait hash write LCDCintroScreen4 wait _hash write LCDCintroScreen5 wait hash while 1 task I2CTWI Q update I2C bus task RP6System update RP6 system menu show menu 78 Interactive Ultrasonic Guided System E Datasheets All the datasheets are included in the CD ROM See Appendix F 79 Interactive Ultrasonic Guided System F CD ROM contents At the end of the report a CD ROM is attached including all the additional data that due its extension or features have not been included in the report The software developed during the project is also included Below are listed the contents of the CD ROM Results Files of the software developed Final Report in pdf format RP6 Robot System User s Manual Datasheets of the components included the microcontroller Set en
3. The final test of the complete prototype will be done WBS 8 The final report will be written which includes all the work done and the final conclusions WBS 9 Finally the viva voice and poster presentation will be prepared WBS 10 57 Interactive Ultrasonic Guided System 3 3 Programme A Gantt chart is attached 4 Dependencies Electronics Laboratories of Computer amp Technology Building will be needed for doing all the necessary tests 5 Risk management l 2 Non availability of Pc causing delay and loss of project data This risk will be managed by saving all the work in UCLan servers because they are more safety Loss of project documents A back up of the hard drive containing all the data will be done everyday automatically to an external hard drive preventing the possible failure of the computer hard drive Delays in procurement of components leading to failure to complete on time This risk will be managed by ordering all components at least 15 working days before they are needed 6 Deliverables Ttem Due date Progress Report 29 Oct 2010 Final report 2 copies 15 Apr 2011 7 References Bishop R H 2008 Mechatronics systems sensors and actuators fundamentals and modelling Boca Raton CRC Press 58 Interactive Ultrasonic Guided System C Software block diagrams In this appendix are included the block diagrams considered necessary for the understanding
4. This data communications bus is explained in depth in chapter 3 2 1 2 3 2 2 Expansion connectors The robot has two expansion buses or XBUS that permit the power lines and some other useful lines to be available in other places of the robot such as the upper platform The pinout of the connector is SDA and SCL are the connections of the I2C bus GND INTI INT2 and INT3 are the interrupt inputs of the uC SDA SCL INT1 VDD is the 5V power supply UB UB GND MRESET INT2 INT3 INTU VDD VDD GND XBUS1 2 Figure 2 5 Expansion bus connector 1 UB is the battery voltage JUANA MRESET is the Master Reset Signal of the uC Re ON GND is the ground connection It also has another two expansion connectors called USRBUS1 2 that allow the user to make connections between expansion modules They just provide a connection between two boards and they do not have any specific pinout Information obtained from 1 0 SDA Serial DAta line 11 SCL Serial CLock line 16 Interactive Ultrasonic Guided System 2 3 4 Power supply The power supply is obtained from six AA type batteries They provide a total voltage of 7 2V since each one of them has a 1 2V voltage Due to the characteristic of rechargeable batteries 1f they are completely charged they can offer up to 9V This is the cause of the voltage variations in the signal UB and the fluctuation depends on the charge level of the
5. keypad register low byte keypad low byte I2CTWI readByte LCD ADR key pressed keypad low byte keypad high byte lt lt 8 2 5 Wait hash void wait hash void int cont 0 is only the variable for controlling the loop while cont keeps reading the keypad until the is pressed read_keypad if key 11 11 is the value assigned for the key cont 1 mSleep 500 2 6 Read value uint8_t valuej stores the value introduced with the keypad void read value char screen 80 value 0 write LCD screen I2CTWI transmit2Bytes LCD ADR 0 2 set cursor to a position I2CTWI_transmit2Bytes LCD ADR 0 50 position 50 in the middle of the third line I2CTWI transmit2Bytes LCD ADR 0 6 blinking cursor read _keypaa read tents 70 the Interactive Ultrasonic Guided System store tents I2CTWI transmit2Bytes LCD ADR 0 keychar show key pressed in the screen read_keypad read units value 10 key store units and add the tents I2CTWI transmit2Bytes LCD ADR 0 keychar show key pressed in screen I2CTWI transmit2Bytes LCD ADR 0 4 Hide cursor mSleep 1000 3 Definition of object avoidance functions uintl6 t distance 3 1 Take measure distance of the measurement void takeMeasure void while end static uint8 t measureInProgress false static uint8 t dist high byte static uint8 t dist_low byte
6. 6 3 5 Main program 6 3 5 1 Main program code in page78 and block diagram in page 65 The main function initialises and configures the following systems RP6 robot I2C communications bus ultrasonic range finder and the LCD display After that it shows the welcome screens and at the end it enters in an infinite loop Each time the program goes across this loop the RP6 and the I2C bus are checked and updated and the function menu is executed 46 Interactive Ultrasonic Guided System 6 4 Test results 6 4 1 Measuring distances with the ultrasonic sensor The accuracy of the sensor has been tested using the terminal of the RP6 Loader A program has been developed with the objective of reading the values measured by the sensor and showing them in the terminal The tests showed that the sensor has a satisfactory accuracy In the table number there are some results Real Distance cms Sensor measured distance cms 3 4 10 10 50 50 Table 7 Ultrasonic sensor test of measured distances The material of the surface that reflects the ultrasonic wave can also alter the measures These are the data collected in a test done with different surfaces and all of them at the same distance from the sensor The real distance is Material Real distance cms Sensor measured distance cms Plastic 15 15 Varnish wood 15 15 Fabric 15 15 Table 8 Ultrasonic sensor test depending on the refle
7. With the data obtained in 3 it is possible to get the value of q the angle the robot should rotate in order to follow a parallel path respect to the wall as shown in the Figure 4 7 p 45 B 4 Combining 2 3 and 4 the complete equation that obtain the escape angle is i right measure left_ measure 37 Note that if the robot approximates to the wall in a different angle that the shown in the example the values for calculating the function arctan can change The numerator always has to be the longer one of both measures 33 Interactive Ultrasonic Guided System 5 The Interactive Display System 5 1 LCD display basics The purpose of a display is to convert electric signals into visual information A display is composed by small areas called pixels The different pixels of the display are switched on and off and all of them together create the desired image to show There are two basic types of displays depending on the shape of their pixels seven segment displays and dot matrix displays 9 Their structure is shown in the next figure CRE im Figure 5 1 Seven segment and dot matrix display 9 OOOoOoOooO Ooooooo OOOOoOoOoO OoOoOoooo pododoo Depending on the way the pixels are activated it is possible to differentiate between active and passive matrix The active matrix displays have one semiconductor device in each pixel for turning it on and off Normally it is a transistor
8. int end 1 if measureInProgress loop for starting the measure process the command 81 orders the SRFO8 to get the measure result in centimetres I2CTWI_transmit2Bytes SRF_ADR 0 81 measurelnProgress true setStopwatch1 0 start the counter from 0 else if getStopwatch1 gt 70 after 70 ms the wave has returned to the sensor and the result can be measured measurelnProgress false request and receive of the high byte range register I2CTWI_transmitByte SRF_ ADR 2 dist high byte I2CTWI_readByte SRF_ADR request and receive of the high byte range register I2CTWI_transmitByte SRF ADR 3 1i dist_low_byte I2CTWI_readByte SRF_ADR join the two registers in one value distance dist_low_byte dist_high_byte lt lt 8 end 0 71 Interactive Ultrasonic Guided System 3 2 Explore uintl6 t distanceRight 0 distance measured in the right point uintl6 t distanceLeft 0 distance measured in the left point void explore void turn right the value of degrees_explore for obtaining the measure on the right side rotate 40 RIGHT degrees explore BLOCKING takeMeasure take a measure distanceRight distance store the read distance this lines are for showing the result in the terminal of the RP6 Loader writeString P AnDistance Right writeInteger distanceRight DEC writeString PC cmin turn left for obtaining the measure of the left
9. of some functions The green boxes are references to a specific function 1 ULTRASONIC SYSTEM FUNCTIONS essseeeseoessoesssesssesssecssooesoossssesssesssoessoossossssse 60 ll TAKE MEASURE FUNCION cs a A ak 60 122 4 IEONCTION EXPLORE at lei o do 61 Ls FUNCTION ESCAPE AUTO tata A A A A Na EET 62 LA FUNCTION ESCAPE MANUAL hie tute esa eaten s atest 62 1 5 FUNCTION START EXPLORING A 63 Ze MENU FUNCIIONS issscsccussecsdessusessscsaudsooushesssoosoedessuupiesoeuasdeoavovpaasscussarsenssstavedsatsecbes 64 2il SELECT PARAMETERS tr OS 64 2 27 BACKLIGHT encena neit ai es os Se Se tates Re aes teas Se ate a a ak 65 Dede NUI MEN E e eek heads att 65 3 MAIN PROGRAM cin il 66 59 Interactive Ultrasonic Guided System 1 Ultrasonic system functions 1 1 Take measure function TAKE MEASURE MEASURE IN PROGRESS REQUEST RESULT IN CENTIMETERS v TIMER 0 TIME gt 70ms N9 YES y READ HIGH BYTE y READ LOW BYTE v CALCULATE MEASURED DISTANCE END o Figure C 1 Take measure function 60 Interactive Ultrasonic Guided System 1 2 Function explore AS EXPLORE A v TURN 45 RIGHT AA TAKE MEASURE y TURN 90 LEFT y TAKE MEASURE y RETURN TO INITIAL POSITION END Figure C 2 Function explore block diagram 61 Interactive Ultrasonic Guided System 1
10. HA SH NAS EA EAS CR a 70 DOs READ VALUE E E E E E IS 70 DEFINITION OF OBJECT AVOIDANCE FUNCTIONS cccccsssssssssssssssssveees 71 Sule TAKE MEASURE di da ia aci 71 ln EXPLORE A di odo 72 3 AUTO ESCAPE ia 72 3 48 MANUAL ESCAPE Sia ti E TE 73 3 5 START EXPLORING 2d E RIA A steals E oka Di gece tes A Sale NRE ia ti n 74 DEFINITION OF MENU FUNCT IONS cccccssssssssssssssscssssssssssssssssssssssssssssscees 75 4 1 PREDEFINED VALUES a eee 75 4 2 SELECT VALUES A A A A Uae 75 Ao oO AE E E A E EA A A aR ens 77 AAs MENO rasta tate decd EEE AEAEE A 77 MAIN PROGRA Miiisenichesese cscs sboctesevetecssZasedieletenecesess ontasesetensssadestetedesecscessestesedetessscaseos 78 Di MAINPROGRAM ts cet eet ls A a Bib dhs eel aa bas ao tuba Ms aaa 78 67 Interactive Ultrasonic Guided System 1 Libraries and definitions in fin in fin clude RP6RobotBaseLib h clude RP6I clude lt avr clude lt math 2CmasterTwI c pgmspace h gt h gt define SRF_ADR OxEO address for the ultrasonic sensor in the I2C bus define LCD_ADR Oxc6 address for the LCD display in the I2C bus int correction 0 value for the correction of the motor deviation int degrees explore degrees the robot rotate when it is taking measures int degrees escape degrees the robot rotate to avoid the object int stop distance distance to an object that makes the robot stop int speed explore speed int
11. J Borestein 25 Interactive Ultrasonic Guided System robot analyses and stores various environmental factors Figure 4 1 which allows the robot to easily and quickly find its way to a predefined goal Figure 4 2 Obstacles The traveled paths Goal Figure 4 2 Goal seeking 8 There are some examples of papers based on both techniques included in the CD attached 4 2 Time of flight The values generated by the ultrasonic sensor are obtained using a technique called time of flight TOF This technique is based on the physics elementary formula which states that the distance equals the speed multiplied by time distance speed x time In order to calculate the time the system has an emitter that sends an energy wave When this wave hits a surface it is reflected and comes back to the receiver The time the wave spends in this process is measured 26 Interactive Ultrasonic Guided System The other factor in the equation is the speed In this particular case it is the propagation speed of the wave that the emitter sends This value depends on the transmission medium which in this case is the air After getting these values calculating the distance is easy TOF systems can have the following error sources Variations in the propagation speed the speed of the acoustic waves is influenced by changes in the temperature and in the humidity Uncertainties on calculating the travel time of the wave can
12. batteries 1 The robot system is equipped with a 5V regulator capable of supplying a maximum current of 1 5A but it is recommended not to use more than 800mA without using an additional heat sink 1 1213 1415 d as well as chargers but in the end some Some rechargeable batteries were studie batteries were borrowed from the lab Their performance was not as expected so finally traditional alkaline power cells have been used for all the tests made for this project Only three packs of six batteries have been spent since the power consumption of the robot has not been too high 12 http uk farnell com ansmann 5035201 battery rechargeable nimh aa dp 1453781 Ntt 5035201 13 GP 2700mAh AA rechargeable batteries from Rapid electronics now they are discontinued 14 http www2 conrad uk com goto php artikel 250125 S http www2 conrad uk com goto php artikel 235703 17 Interactive Ultrasonic Guided System 3 The working environment 3 1 Software The main objective of the project is to develop the necessary software to manage the robot This chapter explains all the software resources used for creating the robot software and the subsequent process of programming the microcontroller All the programs are running under Windows XP Professional Version 2002 SP3 3 1 1 GCC GNU Compiler Collection The abbreviation GCC stands for GNU C Compiler When it was created it only entailed C language but nowadays some othe
13. be caused by the different reflectivity of the measured surfaces or by the signal attenuation with the distance Inaccuracies in the circuit that measures the flying time the circuitry must be faster than the time the wave takes in coming back so the nearer the target is the faster the circuit has to be Surface interaction if the angle of incidence of wave sent to the surface exceeds a determined value the reflection of the wave may not return to the position where the receptor is All the information of this section has been obtained from 7 27 Interactive Ultrasonic Guided System 4 3 Ultrasonic sensor choice There is a wide range of ultrasonic distance sensors on the market but there are only a few which use the I2C communication protocol After researching on the Internet there were three different possibilities to choose from The first one is the USR40x from www mindsensors com but it is discontinued and not sold anymore The other two options are both manufactured by the British company Devantech The suitable models for the project are the SRF02 and the SRFO8 They have similar characteristics but there are some slight differences between them According to the FAQs of the manufacturer both sensors have similar beam patterns but the SRF08 beam is wider than the SRFO2 and this is a determinant factor since the robot uses only one sensor and the wider the beam is the better it is to accomplish t
14. the escape angle using the obtained values The ultrasonic sensor is taking measures all the time and when the distance obtained segment OB is less than the selected stop distance the robot stops point number 1 of Figure 4 7 Once the robot has stopped point 2 it rotates 45 to its right and takes the distance to the wall Right measure segment OC It comes back to its initial position turns 45 left and takes again the distance to the wall Left measure segment OA Then the microcontroller calculates the escape angle and the robot rotates the obtained angle value and continues forward in a path parallel to the wall point 3 Figure 4 7 Objects Avoidance Strategy The calculus of the escape angle is based on the trigonometry of a right triangle 31 Interactive Ultrasonic Guided System The triangles are shown in Figure 4 8 and the angles in Figure 4 7 Figure 4 8 Escape angle calculation The first triangle is formed by the wall the left measure and the right measure The a angle of Figure 4 9 can be calculated by applying the following formula right _ measure tana a 1 left _measure so the angle is obtained from 1 right _ measure q arctan 2 left _measure Figure 4 9 Escape angle calculation 2 32 Interactive Ultrasonic Guided System From the right angle and the value of a in 2 the angle P can be incurred p 90 a 3
15. ultrasonic sensors since the I2C bus has the capability of managing up to 127 devices With three sensors the same algorithm for avoiding objects can be used The two new sensors can be installed in the robot in a position of 45 degrees respect to the middle sensor Figure 7 1 so the rotate movement for taking measures is not necessary anymore The measures are done faster and they are more reliable since the possible rotate errors are eliminated Figure 7 1 Future work 53 Interactive Ultrasonic Guided System 8 Conclusion The work of the whole year has paid off and the project has accomplished its main objective of avoiding objects using an ultrasonic sensor The software developed meets the requirements of control an ultrasonic sensor and manage the results obtained The algorithm designed for avoiding objects is mathematically justified and is really simple to implement However there are some problems that do not allow the system to work with a high accuracy Regarding to the motion system the motors cannot be calibrated with a high precision This is problematic because the robot is not able to move forward in a completely straight line That is also the cause of the mistakes in calculating the new robot path since the rotation movements are not accurate and the measures are not taken in the correct place The LCD display system works well and does what it is required to do The amount of memory needed to fill the en
16. 3 Function escape auto gt es APA DISTANCE RIGHT DISTANCE LEFT y CALCULATE ESCAPE ANGLE y ROTATE RIGHT AUTO ESCAPE v COMPARE MEASURES DISTANCE LEFT v i ROTATE RIGHT 90 MOVE FORWARD END SA AS DISTANCE RIGHT lt DISTANCE LEFT Y CALCULATE ESCAPE ANGLE v ROTATE LEFT Figure C 3 Auto escape function block diagram 1 4 Function escape manual DISTANCE RIGHT gt DISTANCE LEFT ROTATE RIGHT USER SELECTED ANGLE Figure C 4 Manual escape function MANUAL ESCAPE y COMPARE MEASURES y DISTANCE RIGHT DISTANCE LEFT A S ROTATE 180 y MOVE FORWARD y END 62 DISTANCE RIGHT lt DISTANCE LEFT ROTATE LEFT USER SELECTED ANGLE Interactive Ultrasonic Guided System 1 5 Function start exploring START Y EXPLORING gt v MOVE FORWARD 4 es AA TAKE MEASURE b DISTANCE lt NO STOP DIST YES STOP y WRITE LCD v EXPLORE v Auto mode lt ESCAPE MODE gt Manual mode AUTO MANUAL ESCAPE ESCAPE oy CLEAR SCREEN Figure C 5 Start exploring block diagram 63 Interactive Ultrasonic Guided System 2 Menu functions 2 1 Select parameters SELECT O SET ESCAPE TYPE MAN gt Y READ VALUE YES OUT OF RANGE NO VALUE DEGREES EXPLORE READ VALUE YES OUT OF RANGE VALUE gt DEG
17. 35 result in degrees rotate 40 LEFT degrees escape BLOCKING changeDirection FWD moveAtSpeed speed correction speed writeString PC TURN LEFT n distance stop distance l if the distances left and right are equals it means that the robot is perpendicular to the wall so for escaping in parallel to the wall a 90 degrees turn is required This turn is towards the right but it perfectly could be on the left rotate 40 RIGHT 90 BLOCKING changeDirection FWD moveAtSpeed speed correction speed distance stop distance l 3 4 Manual escape void escapeman void if distanceLeft lt distanceRight elsif else the robot rotate the degrees selected by the user rotate 40 RIGHT degrees escape BLOCKING and move forward changeDirection FWD moveAtSpeed speed correction speed writeString PC TURN RIGHT lAn show in terminal distance stop distance 1 distanceLeft gt distanceRight this is the same as the previous loop but it is used when theleft distance is larger than the right one rotate 40 LEFT degrees escape BLOCKING changeDirection FWD moveAtSpeed speed correction speed writeString PC TURN LEFT n show in terminal distance stop distance l if the distance left is equal to the right distance the robot turn 180 degrees rotate 40 LEFT 180 BLOCKING changeDirection FWD move
18. AtSpeed speed correction speed writeString PC TURN 180 DEGREES n show in terminal distance stop distance 1 173 Interactive Ultrasonic Guided System 3 5 Start Exploring char startExploringScreen1 80 PROGMEM OBJECT DETECTED void startExploring void changeDirection FWD moveAtSpeed speed correction speed while 1 this loop is executing always until the robot is switched off It is always taking measures until one of them is smaller than the set stop distance task I2CTWI Q check and update I2C bus task RP6System check and update RP6 go forward and take measure changeDirection FWD moveAtSpeed speed correction speed takeMeasure if distance gt stop distance no object detected changeDirection FWD moveAtSpeed speed correction speed else object detected stop robot stops task RP6System show in terminal writeString PC n n STOP n n writeString PC OBJECT DETECTED n write LCD startExploringScreenl blinking explore if Cescapetype select escape auto or manual escape auto escape else escapeman manual escape I2CTWI_transmit2Bytes LCD ADR 0 12 Clear screen 74 Interactive Ultrasonic Guided System 4 Definition of menu functions 4 1 Predefined values char predefValueScreen1 80 PROGMEM The predetermined values are go
19. LIMINARY RESEARCH coccion 9 LalsINTRODUGTION lia 9 1 2 EVOLUTION OF THE PROJECT cccccccccccccesssssesceccccccesessssscecccsccauesssscscccssesseueessesscsseeeseaenenss 9 2 THE RPO ROBOT civiccssvcsiccsicicies cetciscesackcsceieissscesascsceeceissssetescsdeeteisscceteccsdestessiseesescseeeds 11 2D INTRODUCTION aa aaa 11 2 DUMEAIN CHARACTERISTICS A a ai 11 2 3 DETAILED FEATURES vida a oie uid A A nl 13 2 3 i Microcontroller oee cad ceases a A ks Sakae us tena Cosa we Rta a Sie es 13 2 3 2 MONOS SV AA RA Oona A eM eat 15 2 3 3 Expansion SYSCOM eccccccccccccsecessseceesseceesseceeseecesseeceeaeeceeseecneceecueeeecneeecseeecseeeeneeenaas 16 a 17 3 THE WORKING ENVIRONMENT enonenononononosososososososososonosososonososocososonosonosososmmmmmm 18 IAS O ET WARE VA A NA IA AA A AAA A A A 18 3 1 1 GCC GNU Compiler CONE A aaa 18 31 2Programmer sn tep d EAS AA A AS 19 SAS RPOLOA dt ds dd dd ae daa od Dd 19 BEPA a FIDANI t PENERE EEIEIEE os a Lak E Neh Bean RE A AAA es a ete 21 E OR A E TN 21 3 2 2 Serial COMMUNICATION ooo 24 4 THE ULTRASONIC OBJECT AVOIDANCE SYSTEM ccononononononosisososososom 25 4 1 CURRENT RESEARCH ON OBJECT AVOIDANCE STRATEGIES cscsceccccccccscessescescecceseesenenss 25 AD IME OB BLIGHT A A id ios 26 4 3 ULTRASONIC SENSOR CHOICE ceccccccccccssssesceccccceccusssescsccccceccaueusscsceccesesaueueasscescesesseanenenss 28 4 4 THE SRFO8 ULTRASONIC SENSOR ccsssssceccccccccsessssesccccceccussssssscecccsceesuusasce
20. Mh Nickel Metal Hydride 12 Interactive Ultrasonic Guided System 2 3 Detailed features This chapter describes the systems used in the project in detail In Figure 2 1 shows a general overview of the robot systems and its main connections EXPANSION SYSTEM I2C BUS Interrupts Reset MOTOR RIGHT H BRIDGE DRIVER ENCODER BUMPER CURRENT SENSING q TWI 1 0 E ATMEGA32 _ 19 a usart 1 0 E MOTOR LEFT DRIVE SYSTEM H BRIDGE DRIVER ENCODER CURRENT SENSING IRCOMM Gh 5V LDO Regulator PC CONNECTION via USB Interface VOLTAGE SENSOR BATTERY SENS 5 CONTROL SYSTEM POWER SUPPLY Figure 2 1 Overview schematic of the RP6 Robot System 1 All the information in this chapter including schematics and datasheets is taken from 1 and is included in the attached CD 2 3 1 Microcontroller The robot uses an Atmega32 microcontroller manufactured by Atmel 2 It is an 8 bit microcontroller that has 32KB 32768 Bytes Flash ROM memory and 2KB 2048 Bytes of RAM memory It runs at a frequency of 8 MHz but it is capable of working with a 16MHz clock The system uses the 8MHz clock frequency for power saving reasons 13 Interactive Ultrasonic Guided System The microcontroller has two communication modules the UART for serial communication with the computer and the TWI
21. REES ESCAPE lt Y READ VALUE YES OUT OF RANGE NO v VALUE STOP NO DISTANCE lt Y READ VALUE YES OUT OF RANGE NO NA VALUE SPEED END Figure C 6 Select parameters function 64 Interactive Ultrasonic Guided System 2 2 Backlight BACKLIGHT BACKLIGHT BACKLIGHT OFF 4 2 MENU 1 BACKLIGHT ON Figure C 7 Backlight function block diagram 2 3 Main menu MENU Y SHOW MENU SCREEN v READ 1 Auto mode i KEYPAD gt 3 Backlight 2 Manual mode y y a PREDEFINED SELECT Sees PARAMETERS PARAMETERS START EXPLORING END Figure C 8 Main menu block diagram 65 Interactive Ultrasonic Guided System 3 Main program MAIN y CONFIG RP6 y CONFIG 12C y CONFIG SRF08 v CONFIG LCD AA INTRO SCREENS y UPDATE 12C UPDATE RP6 v MENU Figure C 9 Main loop block diagram 66 1 2 Interactive Ultrasonic Guided System D Software code LIBRARIES AND DEFINITIONS cccssssssssssssssssssssssssssssssscssssssssssssssssssssssecess 68 DEFINITION OF DISPLAY FUNCTIONS e e e 0000000000000000000sososososososososososososososos0 68 P A A NONE ETE TAE S SEA A hse 68 2D N i T AVAA S O E E E E E E E E E ees 68 DI WRITE COD zinenean an a r e chs n a e aa a r Aad 69 ZA READ REY PAD cit ai ias aT 69 Dz WA
22. School of Computing Engineering and Physical Sciences Sergio Zapatel Interactive Ultrasonic Guided System EL3990 Submitted in partial satisfaction of the requirements for the degree of Bachelor of Engineering with Honours in Electronic Engineering April 2011 I declare that all material contained in this report including ideas described in the text computer programs and drawings is my own work except where explicitly and individually acknowledged Interactive Ultrasonic Guided System Abstract This project is about developing software capable of controlling a prebuilt robot with an added system for measuring distances using ultrasonic waves The software will handle the ultrasonic sensor for detecting obstacles that stand in the way of the robot and after that it will be capable of deciding which path the mobile should follow The system is controlled using a simple keypad and the user has to follow the instructions showed in an LCD display Interactive Ultrasonic Guided System i List of Figures Figure 2 1 Overview schematic of the RP6 Robot System 1 oooooonnccnnncnnocnnnncnonccconccanoos 13 Figure 2 2 A TMEGAS2 Block Diagram 2 dd iaeue 14 Figur 2 3 Mosfet H bridge 1 encis iaiia tinerii di israse 15 Figure 2 4 PWM regulation li Sacer NA e ies 15 Figure 2 5 Expansion bus connector Ul ac assewaas dice cs 16 Figure 3 1 About of Programmer s Notepad 2 cccccccssecssecssecsseeeesce
23. System 1 Overall design and preliminary research 1 1 Introduction The idea for this project came from my supervisor Phil Tranter From a list of possible topics I chose the three most interesting for me The aim of the project is to develop an ultrasonic guided system applied in a mobile robot in order to avoid objects Furthermore the project will provide a total remote control for the robot via a radio communication system of 434 MHz All the systems must be included in a single PCB that fits in the robot bodywork In addition to this a remote control must be constructed 1 2 Evolution of the project The development of the project has had three main structural changes At the beginning the project consisted of the creation of the motion system for the platform the design of the ultrasonic avoidance object system and the implementation of the wireless remote control At the end of November my supervisor offered me a complete robot system called RP6 which improved my project possibilities because it has an integrated motion system that I can use instead of designing my own system The robot system also includes an 1C interface which was another topic of the proposal projects The characteristics of the robot system are explained in the Chapter 2 At this point the decision was taken to pursue a new direction of the project and to start focusing more on software rather than hardware 434 MHz band PCB Printed Cir
24. able Read Only Memory PO adan loa First Input First Output ETDI AAA Future Technology Devices International Ltd AA GNU is Not Unix GUES ia GNU Compiler Collection Catas Integrated Circuit OS Infrared 1er a CAE Inter Integrated Circuit o AA Liquid Crystal Display MD iia Multiple Document Interface MOSFET vscsccsssesesteceves Metal Oxide Semiconductor Field Effect Transistor INIMD a Nickel Metal Hydride PCB iranieni Printed Circuit Board PEM ied eee Potential Field Method BW count es os Pulsed Wave Modulation SRAM anin Static Random Access Memory ROM ada Read Only Memory RP an Robot Project 6 Uan Serial Clock SDA cusscagatoetadivatinatandes Serial Data SRE eaeko iih Sonic Range Finder A ealn Time Of Flight AA A Two Wire Interface it is a synonym of I2C DAR Tania Universal Asynchronous Receiver Transmitter USB das Universal Serial Bus Interactive Ultrasonic Guided System Contents ABS ERA G isscic cescascasteecesetetindeteicussecsntescassensepasesusteseususseseuastisiessudsousedsebodsusadasouacdsovesensesessceete 2 Te LIST OR EIG URES sesesariedoeesc cade ceetceicthieactscredietecesencee cacacecetevesceccgedecdosesecccessescsccteseaceceseceere 3 TE BIST OBR TABLES wisdicdeccecdesttasccccccscccctstevcaccetccsctedescaccececcdeveSevcaccesaccucdedecceceecsecdceessvcbcceseccea 5 HI LIST OF ABBREVIATIONG cccccssssscsssssssssssssssssssssssssssccccccccccccsccsssccscscssscssscssscssees 6 1 OVERALL DESIGN AND PRE
25. aken from http www lammertbies nI comm info I2C bus html 21 Interactive Ultrasonic Guided System The PC is a bidirectional serial communication system and the transmission can be done with only two lines called SDA and SCL SDA is used for transmitting the data bits and SCL is a clock signal The data sent through the SDA line include the address of the device required and also the data requested Depending on the specification adopted the communication speed is Standard mode Sm 100 kbits per second Fast mode Fm 400 kbits per second Fast mode plus Fm 1 Mbit per second High speed mode Hs mode 3 4 Mbit per second Table 1 Communication Speed Values of the 12C bus 3 The main characteristics of the I C bus are 6 Simplicity and flexibility TWI Two wire interface only two bus lines are required No strict baud rate required Simple master slave relationships between all components This is the typical hardware configuration for an I2C link Vcc 12C Device 1 12C Device 2 SDA in SDA in SDA out 20 i FSi e SDA out SCL in SCL out A Figure 3 4 Typical Configuration of an PC link 6 22 Interactive Ultrasonic Guided System The elements of Figure 34 are VCC Supply voltage GND Common ground SDA Serial Data line SDL Serial Clock line Rp Pull up resistance Rs Serial Resistance Cp Wire capacitance Ce Cross chann
26. asonic Guided System 6 3 Software The robot microcontroller is programmed in C language The developed program has been divided in several parts depending on the system the code is referring to This separation helps to test specific sections of the code without compromising the rest of the program It is also based on a large number of functions since this way the code is neat and more efficient There are three groups of function declarations The first two have the purpose of controlling the hardware system one is composed by the functions that control the ultrasonic sensor and the other one is in charge of the LCD display and the keyboard matrix The third group is responsible for the software of the functions that appear in the main menu After that the main program is declared which includes an infinite loop with the main menu included Therefore the basic structure of the software is the following Include libraries Variables and constants declaration Declaration of LCD display and keypad functions Declaration of ultrasonic sensing functions Declaration of main menu functions Main loop In the following chapters the purpose of each function will be explained Appendix C includes some block diagrams designed for better comprehension of the code which is included in appendix D Their location is referenced next to the name of each function 40 Interactive Ultrasonic Guided System 6 3 1 Libraries The pr
27. bute by Dean Camera included in the CD ROM This information is also in the official AVR libraries website http www nongnu org avr libc user manual pgmspace html http www nongnu org avr libc user manual group__avr__ pgmspace html 43 Interactive Ultrasonic Guided System First of all it uses the function init_cursor for initializing the cursor and after that it sends the characters one by one until the screen is complete Note that the characters are read from the program memory and the function pgm_read_byte is used for retrieving the data 6 3 2 4 Read keypad code in page 69 This function is in charge of reading the keys pulsed by the user It recognizes what key is pressed and also includes a string with its the name which is useful for showing the key value on the screen It is important to detect only one pulsation each time the key is pressed so the function waits until the key is released for returning the result required 6 3 2 5 Wait hash code in page 70 A signal from the keypad is needed to move to the next screen and the key has been chosen This function waits in a loop until the mentioned character is read 6 3 2 6 Read value code in page 70 This function reads the values introduced by the user in the manual mode and it also shows the characters read in the screen 6 3 3 Ultrasonic system This group contains all the functions relating to the object avoidance system They are in
28. cceseeeeanenenss 29 4 5 STRATEGY FOR THE OBJECT AVOIDANCE cccccccccccsssssseccccceccusesssssceccescceseusasscecceseeeeunenenss 31 5 ES Interactive Ultrasonic Guided System THE INTERACTIVE DISPLAY SYSTEM uu ccsssccssssssscssssssssccssssssccsssesessccsssessces 34 dl LCD DISPLAY BASICS A A E RRE ails 34 3 2 LCD DIS PIA Ysa ead sca Ui a Geass a a a each Mas ase Naas Eases 35 DO IMA TRES K YPAD rain RN AAA AA AAA NAAA 37 RESULTS ad O iaa 38 6 1 FINAL RESULT a a 38 0 2 HARDWARE 00 a aa a a a a a 39 6 3 SOFTWARE it a a a a a a aara 40 OSE LiBr ES A diia 4 6 3 2 LED display and Matrix keypad JUNCOS a 43 6 3 3 Ulir sonie SEN io laica 44 6 3 4 Menu LUNCH ONS RA AAA AA 46 6 3 3 Main RO E aos WaPo AG Deane eae aa eH SONAL a oe 46 GA TESTRESUL T Sariana a lio Aaa 47 6 4 1 Measuring distances with the ultrasonic SensOT oooonnninniinnnnnnnnnnnnccnnccinnccarrrnnrcannno 47 AZ The Motion SYSTEMA Lied ain EAEN RE AE E A cd 48 6 4 3 The object avoidance SUSE AAA A AAA 51 6 4 4 The LCD Display A ie nde ayotecea tateasgbivi ote Machag nde 52 FUTURE WORK ia 53 CONCLUSION aia 54 BIBLIOGRAPHY nes A AS 55 STATEMENT OF WORK 000 56 SOFTWARE BLOCK DIAGRAMS occncconconosonsonssonconcsonconocoocconcconcasocencorococcconcccncac osos 59 SOETWARE CODES ura dai 67 DATA SHEE ES ra a dd ii 79 CD ROM CONTENTS cis sccsnsinssenscisacdescsvedssonsasicsselsvogssassacdesssoudonatsaatacs sbvaascsassaidesalOaeagn 80 Interactive Ultrasonic Guided
29. ceeceseeseeeesaeecsaeceseeneees 19 Figure 3 2 RP6 Loader Screenshot o cisc5 eiosd Seaais tia ds 20 Figure SECO a aca 21 Figure 3 4 Typical Configuration of an C link 6 c scscesscssessessessessessesesstssessesseesesseeseeseesen 22 Figure 3 5 Board of the serial bus Cal A eeee nae us 24 Figure A earning O e mht eno 26 Pitre 42 GOA li td 26 Fioure 4 3 SRF 02 B am Pr A As aes 28 Figure 44 SRFOS Beam Pattern it das 28 Fioure 4 5 SREOS Prod ad 29 Figure 4 6 SRF08 back side view and connections 4 ooooccnnncninccnnncconccconoconncononcnnnoconocinoos 30 Figure 4 7 Objects Avoidance Strategy consi dida 31 Figure 4 8 Escape angle calculation ci di 32 Figure 4 9 Escape angle calculation Pi ac 32 Figure 5 1 Seven segment and dot matrix display 9 ooonionccnicnncniccnncnoccconcnoconancnncnancnnncnnos 34 Figure 5 2 Passive and active matrix displays liinda 34 Interactive Ultrasonic Guided System Figure 0 1 Hardware A es OS 39 Figure 02 Motion system distancia 48 Figure 6 3 PWM waves before adjustment eecesceseeceeecceeeceecceseesseeseecesseeceecceseeeseeseees 49 Figure 6 4 PWM waves after adjustMeMt ooooonconnonicnnnononnnonnonnnnnncnnnnnn cono nanconnnonnnnn cria conc cnncnneno 50 Figure 6 5 Angle deviation with rotate movement eect cessecceecceseeeseeeeeceeeeeceecceeeeseeseees 51 Figure 7 1 F t re WO 53 Figure Cl Tak meas re O ee E 60 Figure C 2 Function explore block diagram session idas 61 Figure C 3 Aut
30. charge of getting the data from the environment using the SRF08 sensor from chapter 4 3 The first function has the objective of obtaining the distance measures and the rest of them are related to the object avoidance system 44 Interactive Ultrasonic Guided System 6 3 3 1 Function take measure code in page 71 and block diagram in page 60 This function is one of the most utilised since it gets the distance measures from the ultrasonic sensor The sensor requires at least 70ms to have a correct measure because it has to wait until the ultrasonic wave returns to it 6 3 3 2 Function explore code in page 72 and block diagram in page 61 This function is in charge of obtaining the measure of the distance in two different points It makes the robot rotate 45 degrees to each side from the stop position in order to take the measures These measures will be used for deciding the direction to escape The explanation of the purpose of this function is detailed in chapter 4 5 6 3 3 3 Function automatic escape code in page 72 and block diagram in page 62 This function calculates the value of the angle that the robot should turn in order to avoid the object It is based in some mathematical calculations one of them is the function atan2 included in the math h library The escape angle is calculated using the steps explained in chapter 4 5 6 3 3 4 Function manual escape code in page 73 and block diagram in page 62 In this function the
31. coders correctly German Object Avoidance background Tutorial of potential field method Paper about limitations of the potential field method Example papers of Potential Field method Example papers of fuzzy logic systems Ultrasonic Sensor Technical documentation Schematic LCD display Technical documentation Communications Systems 2C bus specification and user s manual Datasheet of serial communication chip FT232R Serial communication schematics Software RP6 Loader RP6 libraries Programmer s notepad Tutorial on PROGMEM attribute Components and robot pictures 80
32. connections With the PC bus is possible to add up to 127 devices and it also includes an expansion bus that helps to connect external devices to the microcontroller 2 2 Main characteristics Atmel ATMEGA32 8 Bit Microcontroller Flexible expansion system based on the I2C Bus Symmetrical mounting possibilities for expansion modules at front and rear USB PC Interface for program uploads from PC to microcontroller Powerful caterpillar drive unit in combination with a new gearing system for minimising noise Two powerful 7 2V DC Motors Two powerful MOSFET Motor drivers H Bridges Two high resolution encoders for speed and motion control 6 MOSFET Metal Oxide Semiconductor Field Effect Transistor 11 Interactive Ultrasonic Guided System Anti collision system ACS with an integrated IR receiver and two IR diodes aligned to left and right Infrared Communication system IRCOMM Two light sensors Two bumper sensors for collision detection 6 Status LED s for sensor and program status displays Two free Analogue Digital Converter ADC channels for external sensor systems Accurate 5V voltage regulation maximum current supply of 1 5A Replaceable 2 5A fuse Low standby current of less than 5mA 4mA typ and ca 17 up to 40mA in use Power supply with 6 NiMh accumulator batteries The main board provides 6 small expansion areas 7 IR Infrared 8 Ni
33. ct After that it takes two distance measures and mathematically calculates the required angle to get away from the object following a parallel path respect to it The detailed explanation of the operation is in chapter 4 5 The second strategy is called Manual mode The user is asked to introduce the desired values with the keypad These values are explore degrees escape degrees stop distance and robot speed After that the object avoidance routine will start using the specified parameters The robot is supposed to be automatic and autonomous so once the program is started it will not stop until the reset button is pressed 38 The reset button of the robot is next to the serial bus connector it is the same as the start button 38 Interactive Ultrasonic Guided System 6 2 Hardware The LCD display and the ultrasonic sensor are both connected using a four line ribbon cable to the power supply and I2C lines of the robot The keypad matrix is connected with a seven line bus to the LCD display which has the integrated circuit that manages the keypad Chapter 3 2 explains the characteristics of the hardware in more detail ULTRASONIC SENSOR SRF08 LCD DISPLAY 20x4 KEYPAD 4115116 711819 0 RP6 ROBOT 502 n00 12C BUS Figure 6 1 Hardware connections Note that the pull up resistors needed for the proper working of the I2C bus are already implemented in the RP6 robot 39 Interactive Ultr
34. ction surface This test shows that the reflection surface material does not affect the measure 47 Interactive Ultrasonic Guided System 6 4 2 The motion system The accuracy of the robot s movements is not very high There are two different motors one for each caterpillar and they cannot be calibrated separately Both encoders are using the same conversion factor but due to mechanical issues they are not providing the same movement to each one of the caterpillar wheels The function moveAtSpeed speedLeft speedRight is used to perform the tests It requires two input parameters and each one of them represent the speed of each motor By observing the robot moving across a theoretically straight line it can be deduced that the left motor runs slower that the right one which ends in a deviation movement towards the left The objective of the tests is to get the values that compensate the difference between the two motors by correcting the left one Deviation _ 7 EA _ gt _ a _ _ a _ Test distance Figure 6 2 Motion system distance test The correction has been introduced as follows moveAtSpeed speedLeft balance value speedRight The chart below shows the deviation of the robot respect a straight line The surface material has not too much influence in this test since both wheels have the same grip and the conditions for each motor are the same The tests were don
35. cuit Board gt RP6 Robot project 6 PC Inter integrated circuit Interactive Ultrasonic Guided System The next relevant change was at the beginning of February The motion system and the ultrasonic object avoiding system were properly working The next step was to develop the wireless remote controlled system After studying the characteristics and regarding to the time left until the end of the project it was decided to leave the wireless remote control and instead implement an LCD display and a keypad This way the control will not be wireless but the system will allow the user to change the different parameters of the object avoidance system without the need of a computer In addition the LCD display also uses the I C data transmission system that will help to demonstrate its capability for managing several devices 5 LCD Liquid Crystal Display 10 Interactive Ultrasonic Guided System 2 The RP6 Robot 2 1 Introduction The RP6 is a mobile robot system designed with the objective of introducing the user to the world of robotics The product is a completely assembled system which includes a microcontroller ATMEGA22 and a large variety of sensors to interact with The robot is the perfect device for research and development of new features since one of its main points is the great possibility of expansion This means it is prepared for adding new modules and allows the user to interact with them using a wide range of
36. e of updating all the systems of the robot It checks and updates the changes in the motion system and other systems not relevant for the project like the analogue to digital converter or the bumpers status 41 Interactive Ultrasonic Guided System initRobotBase this function initializes all the systems of the robot including the configuration of the sensors and the microcontroller stop if the robot is moving a distance or rotating this function stops it immediately 6 3 1 2 RP6uart h writeStringP writes a string from the program memory to the UART writeInteger number base writes a number to the UART and it specifies the base between hexadecimal decimal or binary 6 3 1 3 RP6I2CmasterTWLIh This library has the purpose of controlling the I2C communication bus The functions taken from it are I2CTWI initMaster 100 Sets the operation frequency of the bus the frequency in kHz of the SCL line I2CTWI transmitByte LCD _ADR 1 sends one byte to the specified address 2CTWIL transmit2Bytes LCD ADR 0 19 sends two bytes to the specified address 2CTWI readByte LCD_ADR reads one byte from the address task I2CTWI updates the status of the bus 6 3 1 4 Pgmspace h This library is necessary for managing the memory of the microcontroller The ATMEGA32 has 2KB of RAM memory and 32KB of ROM or program memory The LCD display has 80 characters and each one of them needs 1 byte That means that e
37. e using various correction values in the left motor and with different speed values 48 Interactive Ultrasonic Guided System Speed ies meter Deviation cms 0 6 60 6 4 12 0 0 10 90 6 5 12 1 0 18 120 6 10 12 1 Table 9 Deviation test Considering the results of the test the left motor has been software adjusted using the exemplary value of 12 every time the function moveAtSpeed is called With this value the robot has an acceptable straight movement when it is required However there is another method that can help to improve the behaviour of the motors In both motor drivers there are two potentiometers that control the duty cycle of the PWM wave The RP6 Loader can show the waveform of the PWM signal if the self test program is running If is not properly calibrated you have the possibility of adjusting the PWM duty cycle These are the waves before adjusting the PWM tr Waveform Display ENCODER RIGHT Zoom ps 3 025 Offset la Figure 6 3 PWM waves before adjustment As shown in the Figure 6 3 the square wave does not have a 50 50 duty cycle and it needs calibration 49 Interactive Ultrasonic Guided System It is a delicate operation that must be done in a dark environment since the direct light can damage the optical sensors that read the encoders of the gearbox The only information about this process is obtained from the English s
38. el capacitance As shown in Figure 3 4 a pull up resistor is connected from each line of the bus to the positive rail These resistors are necessary because when the bus is free both lines have to be in high state 23 Interactive Ultrasonic Guided System 3 2 2 Serial Communication The robot is connected to the PC via serial communication It uses the FT232R chip from the manufacturer FTDI that converts the UART signal to USB The circuit includes a LED that lights up when there is some activity The usual transfer speed between the computer and the robot is 500kBaud 1 rr OS as Figure 3 5 Board of the serial bus cable datasheet is included in the CD More info in http www ftdichip com Products ICs FT232R htm 2 ETDI Future Technology Devices International Ltd http www ftdichip com 24 Interactive Ultrasonic Guided System 4 The Ultrasonic Object Avoidance System There are many documented ideas and strategies for avoiding objects and walls Most of the contemporary robots with that objective employ at least 3 different sensors in order to get data from all sides of the robot and decide what to do There are also projects that mount a single ultrasonic sensor but they include a servomotor for making the sensor work as a radar system The budget of this project is restricted and installing more than one sensor or servomotors would exceed the budget The solution adopted is to use a fixed h
39. engines an H bridge motor drive is implemented in each motor It works closing switches in pairs of two If switches S1 and S4 are closed the motor turns in one direction and if the switches S2 and S3 are closed the motor turns in the other direction It is extremely important that when a pair is closed the other one is open since if the two switches of the right S3 and S4 or the two switches of the left S1 and S2 are closed a short circuit will occur and the switches will be destroyed Figure 2 3 Mosfet H bridge 1 With the H bridge we obtain the forward and backward direction of each motor which also allows it to turn left or right depending on the direction of each engine In order to control the speed of the motors the microcontroller uses its PWM output to control each MOSFET The PWM regulates the time the output is in on state Depending on the time the al I output is high respect to the period of the square T 25 t wave duty cycle the average value of the output A l ae T 50 t will be higher or lower which is translated to the iii DC motors through the power MOSFETs altering TA their turning speed The entire chapter is from 1 Figure 2 4 PWM regulation 1 15 Interactive Ultrasonic Guided System 2 3 3 Expansion system 2 3 2 1 The C bus The main expansion system of the robot is the PC bus It allows connecting up to 127 peripherals using only a two wire interface
40. er richtig einstellen Zwolle The Netherlands Arexx Engineering The translated title is Set encoders correctly 55 Interactive Ultrasonic Guided System B Statement of Work EL3990 Statement of Work Interactive Ultrasonic Guided System B Eng Hons Electronic Engineering Issue 1 29 October 2010 S Zapatel 1 Aim The aim of the project is to develop an ultrasonic guided system applied in a mobile robot in order to avoid objects Furthermore a LCD display with a matrix keypad will be added to monitor the activity of the robot and interact with the robot All of these peripherals will be connected using the I2C data communication bus 2 Background There are many existing robot applications which require the robot to be able to avoid obstacles without human supervision A very recommendable way of providing that characteristic is using ultrasonic sensors to detect obstacles Bishop 2008 In order to do so these sensors must be supported by a microcontroller which will determine the new path of the robot depending on the programmed strategy A prebuilt robot will be used to achieve this objective The included microcontroller will be programmed with an algorithm that takes data from an ultrasonic sensor and after analyzing them allows the robot to decide which way it should move to At the same time it is required to monitor and control the system results without the use of a computer in order to let the robot ha
41. escapetype defines auto or manual escape char StartScreen 80 PROGMEM PRESS TO START S 2 Definition of display functions 2 1 Blinking void blinking void int i counter for the times the screen blinks for i 0 i lt 10 i I2CTWI_transmit2Bytes LCD ADR 0 20 switch backlight on mSleep 50 I2CTWI_transmit2Bytes LCD ADR 0 19 switch backlight off mSleep 50 2 2 Initialize cursor void init_cursor void I2CTWI_transmit2Bytes LCD ADR 0 12 clear screen and set cursor at home I2CTWI_transmit2Bytes LCD ADR 0 4 hide the cursor 68 Interactive Ultrasonic Guided System 2 3 Write LCD void write LCD char data 80 init cursor initialize screen for unsigned char i 0 i lt 80 i send 80 chars I2CTWI transmit2Bytes LCD ADR 0 pgm read byte amp Cdata i send to the register O of LCD address the byte that corresponds to the address of the parameter received 2 4 Read keypad int key value of the key pressed uint8 t keychar char of the key pressed used for printing void read _keypad void 1 uintl6 t key pressed 0 represents the register of the keypad key 13 while key gt 11 the keypad register is composed by two bytes uint8 t keypad_high byte uint8 t keypad_low byte asking and reading the value of the high byte of the register I2CTWI transmitByte LCD ADR 2 keypad high byte I2CTWI readByte LCD ADR
42. he mentioned inaccuracies the robot may rotate more degrees until the red position This deviation will cause a wrong escape angle calculation 51 Interactive Ultrasonic Guided System The floor surface is also an important influence in the rotation angle The grip of the caterpillar wheels decreases on tiled or plastic floors and the measures are not correct Surface Requested degrees Real degrees 45 to the left 48 Carpet 45 to the right 42 45 to the left 44 Varnish wood 45 to the right 40 45 to the left 43 Plastic 45 to the right 40 Table 10 Rotational movement test This problem can be solved implementing and additional position sensor to the robot like a compass or a gyroscope to make the rotation angle more accurate 6 4 4 The LCD Display All the commands of the LCD were tested to verify their proper operation 52 Interactive Ultrasonic Guided System 7 Future work The most important improvement can be the implementation of a compass or gyroscope in order to have a proper feedback about the real position of the robot With that information the rotate movement would have a high accuracy which means that the obtained measures for the calculation of the escape angle will be really precise That way the escape angle will be perfectly know The gyroscope will also check that the robot has rotate the exactly escape angle Another form of expansion can be to add more
43. he objective This wide beam difference between the two sensors can be seen in the images below Figure 4 3 SRF02 Beam Pattern Figure 4 4 SRF08 Beam Pattern 30 http www mindsensors com index php module pagemaster PAGE user op view pages PAGE id 49 http www mindsensors com index php module pagemaster amp PAGE_user_op view_page amp PAGE_ id 948M MN _position 20 20 32 http www robot electronics co uk acatalog Contact html 33 SRF ultraSonic Range Finder 4 http www robot electronics co uk htm sonar_faq htm 28 Interactive Ultrasonic Guided System Another difference is the measure range The SRF02 can measure from 15 cm to 6m and the SRFO8 is able to detect objects from 3 cm to 6 m This means that the SRFO2 is not able to recognise objects that are too close which compromise the precision of the object avoidance function In addition to these differences there are some reports of measurement errors using the SRF02 According to the results of the comparison the ultrasonic sensor chosen was the SRFO8 Figure 4 5 SRF08 Front side 4 4 The SRFO8 ultrasonic sensor The main characteristics of this model are Voltage 5v only required Current 15mA Typ 3mA Standby Frequency 40KHz Range 3cm 6m Max Analogue Gain Variable 94 to 1025 in 32 steps Connection Standard I2C Bus Light Sensor Front Facing light sensor 35 The technical data is available at ht
44. igh precision ultrasonic sensor with a wide beam pattern that takes measures in different positions in order to calculate the right path to follow This process is explained in more detail in the chapter 4 5 4 1 Current research on object avoidance strategies In the recent years one of the most popular techniques used in the object avoidance systems is called potential field method or PFM that models the robot and its environment behaviour using field arrows It is a technique that was developed in the eighties but it is still in use although there are some researches that expose its limitations Another popular technique is working with fuzzy logic which consists in considering more than two possible states introducing values between the logic 0 and 1 In this specific example taken from the paper referenced in 8 the robot is using a ring of 24 ultrasonic sensors for taking measures The method is based on having a learning period in which the 2 For example http letsmakerobots com node 5305 Thttp ieeexplore ieee org Xplore login jsp url http 3 A 2F 2Fieeexplore icee org 2Fiel5 2F 1083 1 2F3 4146 2F01626586 pdf 3Farnumber 3D1626586 amp authDecision 203 28 A complete tutorial written by Michael A Goodrich is included in the CD 2 The paper containing that information is included in the attached CD It is called Potential field methods and they inherent limitations for mobile robot navigation written by Y Koren and
45. ind to be used PRESS TO CONTINUE char predefValueScreen2 80 PROGMEM Stop distance 20cm Escape mode AUTO Speed 50 d void predef void escapetype 1 auto escape degrees explore 45 degrees required for the auto escape stop distance 20 predefined stop distance can be changed in E the code but not in the LCD screen speed 60 predefined speed write LCD predefValueScreen1 show info screen in LCD wait_hash write LCD predefValueScreen2 show info screen in LCD mSleep 2500 4 2 Select values char selectScreen0 80 PROGMEM PARAMETERS SELECTION FOR MANUAL MODE PRESS TO CONTINUE char selectScreen1 80 PROGMEM Please introduce degrees for explore in the range of 15 to 90 degrees s char selectScreen2 80 PROGMEM EXPLORE DEGREES char selectScreen3 80 PROGMEM Please introduce degrees for ESCAPE in the range of 15 to 90 degrees de char selectScreen4 80 PROGMEM ESCAPE DEGREES char selectScreen5 80 PROGMEM Please introduce the DISTANCE to STOP in the range of 10 to 50 cms ae char selectScreen6 80 PROGMEM STOP DISTANCE char selectScreen7 80 PROGMEM Please introduce SPEED of the robot in the range of 30 to 80 K char selectScreen8 80 PROGMEM ROBOT SPEED char out_of_range 80 PROGMEM The introduced value is out of range PRESS TO CONTINUE void select void escapetype 03 Set manual esca
46. module used for the IC expansion bus PAO PA7 PCO PC7 vec ne A EFT Mee Mle lle Wee AS A ee le EER 10011000 D EAEE EEEE PORTA DRIVERS BUFFERS PORTC DRIVERS BUFFERS GND PORTA DIGITAL INTERFACE PORTC DIGITAL INTERFACE AVCC OR MUX amp ADC Wi ADC INTERFACE i TIMERS PROGRAM STACK i COUNTERS OSCILLATOR COUNTER POINTER F PROGRAM INTERNAL FLASH OSCILLATOR a aa XTAL1 1 INSTRUCTION GENERAL WATCHDOG i REGISTER PURPOSE H TIMER OSCILATOR E REGISTERS i L x XTAL2 INSTRUCTION i MCU CTRL DECODER I us i amp TIMING T RESET la Z i v i CONTROL i INTERRUPT INTERNAL i CALIBRATED LINES ALU i UNIT OSCILLATOR A AVR CPU STATUS REGISTER i USART i Onn 7 2 i COMP H INTERFACE PORTB DIGITAL INTERFACE PORTD DIGITAL INTERFACE PORTB DRIVERS BUFFERS PORTD DRIVERS BUFFERS PBO PB7 PDO PD7 Figure 2 2 ATMEGA32 Block Diagram 2 The datasheet with the complete characteristics is included in the attached CD UART Universal Asynchronous Receiver Transmitter 14 Interactive Ultrasonic Guided System 2 3 2 Motion system The drive system is based on two DC motors with gearings that move the caterpillar wheels Since the microcontroller is not able to supply enough current to the
47. o escape function block diagram ooonononnnncconacionnnncnonnorocnnnorannnnnn cono canonnonon 62 Figure C 4 Manual escape function ri tna 62 Figure C 5 Start exploring block diagram ssssessessesessseseesesseseesessesesesersesseseesesseseessssesees 63 Figure C 6 Select parameters TU OR 64 Figure C 7 Backlight function block diagram ows spiccedensccasessivsveveicguccclsesees negteaosventeSedeeeeids 65 Figure C 8 Main menu block diagram iis ccsccacehstaedancs messhvsuat leauceeluy easSnsamensvanteSueaeeiss 65 Figure C 9 Main loop dr ces 66 Interactive Ultrasonic Guided System ii List of Tables Table 1 Communication Speed Values of the I2C bus 3 oooooconnccnoconocccinocinancnnncconacancconnnon 22 Table 2 Commands for the REPOS Aid A Sida 30 Table 3 Registers of the LCD display e a 35 Table 4 Commands for the LCD display ia Aeiearetnicke tals atl ace ecctandess 36 Table 5 Matrix keypad VAS it A E A 37 Table 6 Registers used by the matrix keypad eiii ai 37 Table 7 Ultrasonic sensor test of measured dIStanCeS ocoooconoccnocnonoconononcnnnnnncnnnco non ncnnnonncnnncnns 47 Table 8 Ultrasonic sensor test depending on the reflection surface oooooccnnccicccocococcnoncnnnnononns 47 Table 9 Deviation A A tite Unalema ce Bact etait 49 Table 10 Rotational Moy A eds 52 Interactive Ultrasonic Guided System iii List of Abbreviations ATME Esos Advanced Technology Memory and Logic EEPROM oseese Electrically Erasable Programm
48. ogram needs to have a number of libraries Most of them are included in the GCC compiler but there is a group of libraries that have been specifically developed by Arexx Engineering for controlling this robot These libraries include some necessary functions for the proper operation of the RP6 Below is a short explanation about each library and the functions taken from them 6 3 1 1 RP6RobotBaseLib h This library includes the basic operations of the robot The following functions are used mSleep x this routine introduces a delay of x milliseconds in the code It blocks the normal flow of the program until the delay time is finished startStopwatch this function initializes a counter that runs regardless of the normal program flow setStopwatch t sets the counter to a specific t initial value getStopwatch take the instant value of the counter rotate uint8 t desired speed uint8 t dir uintl6 t angle uint8 t blocking makes the robot turn with the selected parameters rotating speed direction of turning rotating angle and an option for blocking the program flow while the robot is rotating changeDirection uint8 t dir sets the turning direction of each motor to move the robot in the required direction The possibilities are FWD BWD LEFT or RIGHT moveAtSpeed uint8 t desired speed left uint8 t desired speed right this routine sets the speed value for each motor task RP6System this function is in charg
49. pe mode write LCD selectScreenl Show info screen of Select explore degrees mSleep 2000 int range 1 while range read value selectScreen2 show screen and read data from keypad if value lt 15 value gt 90 check range write LCD out of range wait _hash 75 Interactive Ultrasonic Guided System else degrees explore value assign value to the variable range 0 write LCD selectScreen3 Show info screen of elect escape degrees mSleep 2000 range 1 while range read _value selectScreen4 Show screen and read data from keypad if value lt 15 value gt 99 check range write LCDCout_of range wait _hash else degrees escape value assign value to the variable range 0 write LCD selectScreen5 Show info screen of Select stop distance mSleep 2000 range 1 while range read value selectScreen6 show screen and read data from keypad if value lt 10 value gt 50 check range write LCDCout_of range wait_hash else stop distance value assign value to the variable range 0 write_LCD selectScreen7 Show info screen of Select speed mSleep 1500 range 1 while range read value selectScreen8 show screen and read data from keypad if value lt 30 value gt 80 check range write LCDCout_of range wait_hash else value assign value to the variable 0 speed range 76 In
50. peaking forum of Arexx Engineering but it is only available in a pdf document written in German 10 which is included in the CD ROM The manufacturer documentation says that an adjustment of 60 40 or vice versa is correct These are the waves after the adjustment fr Waveform Display ENCODER RIGHT Zoom 053 Y 025 Offset la ZoomX 5 025 Offset 03 Figure 6 4 PWM waves after adjustment After executing this process the robot is capable of moving in a straight line without needing the software compensation calculated in the previous test 4l http www arexx com forum viewtopic php t 580 50 Interactive Ultrasonic Guided System 6 4 3 The object avoidance system As mentioned in the previous section the motion system has a remarkable influence on the object avoidance function This task needs the robot to turn 45 degrees to the right and then come back to its initial position and turn 45 left The difference between the two motors is again decisive for achieving the appropriate angles The executed tests show that the rotate function is not accurate and the robot does not stop at the proper angles The calculation of the escape angle is not correct because of this Deviation Figure 6 5 Angle deviation with rotate movement As seen in Figure 6 5 the robot s initial position is the coloured in grey After the rotational movement the robot should be in the green position but due to t
51. r its development and the planning for finishing the project successfully WBS 2 Then the RP6 robot system will be studied WBS 3 beginning with a research on its instruction manual and datasheets WBS 3 1 The research will focus in its motion system WBS 3 2 and the code necessary for achieve the proper movements will be designed WBS 3 3 A test of the robot and the programming will check the proper working of the motion system WBS 3 4 After that a research on the Internet will be done WBS 4 1 in order to find the best solution regarding the ultrasonic sensors i e which kind of sensor and which strategy is going to be used in the project WBS 4 2 The electronic circuit for the ultrasonic sensors will be designed WBS 4 3 and the programming will be done WBS 4 4 A test will be done to check the ultrasonic sensors system WBS 4 5 The next step will be designing the LCD display system WBS 5 A research on that kind of displays will be done WBS 5 1 and the necessary LCD will be chosen WBS 5 2 The robot microcontroller will be programmed for showing the appropriate messages in the display WBS 5 3 The LCD display system will be tested WBS 5 4 exploring all the possibilities of the display Then a general test of the entire system will be done WBS 6 Once checked that all the systems are working properly all the external elements will be added to the robot WBS 7 1 and all the connections will be checked WBS 7 2
52. r languages like Ada Java or Fortran have been added to the compiler The GNU Project is an operative system created by users and its main characteristic is that it is completely free It was launched in 1984 by Richard Stallman and today it is still being developed The GCC is the compiler created for this operative system The first version of the compiler was released on the 22 of March of 1987 and the most recent is from the 25 of March of the current year The GCC compiler is distributed by Free Software Foundation FSF The complete libraries and archives of the compiler and the manuals can be found at http gcc gnu org GNU GNU is Not Unix 17 more info in http www gnu org S http gcc gnu org releases html D http www fsf org 18 3 1 2 Programmer s notepad Programmer s notepad is a free license code editor It supports C language with syntax highlighting and it has a very useful tabbed MDI interface The main features of the program can be found in the developer website The election of this text code editor was made because it is easy to use and at the same time it is a powerful tool for software development It is also the programme recommended by the manufacturer of the robot Programmer s Notepad 2 Version v2 0 8 718 basie Copyright Copyright 2002 2008 Simon Steele Programmer s Notepad uses Scintilla WTL Genx Expat Exuberant CTags and PCRE Thanks to the a
53. robot avoids the object using an angle defined by the user 6 3 3 5 Start exploring function code in page 74 and block diagram in page 63 This is the function that is active when the robot is moving and it does not have any obstacle in front of it It is always taking measurements and when the space between the robot and the object is less than the selected defined in the variable stop_distance it makes the robot stop and execute the functions previously defined called explore and escape 45 Interactive Ultrasonic Guided System 6 3 4 Menu Functions 6 3 4 1 Menu code in page 77 and block diagram in page 65 This function shows a screen with the three options available to choose Then it reads the key introduced by the user and calls the necessary functions to complete the objective of the selected option 6 3 4 2 Predefined values code in page 75 The variables for the object avoidance system are assigned to predefined values The values are detailed in the code It also selects the automatic mode 6 3 4 3 Select parameters code in page 75 and block diagram in page64 This function requires the user to enter the needed parameters for the manual mode It asks for each value and then checks the value is within the acceptable range It sets the escape mode as manual mode 6 3 4 4 Backlight code in page 77 and block diagram in page 65 This menu option allows the user to switch on and switch off the LCD backlight
54. side The degrees are multiplied by two because the robot has to rotate to the initial position and then continue to the final position rotate 40 LEFT 2 degrees explore BLOCKING takeMeasure take a measure distanceLeft distance this lines are for showing the result in the terminal of the RP6 Loader writeString PC nDistance Left writeInteger distanceLeft DEC writeString PC cm n gt return to initial position rotate 40 RIGHT degrees explore BLOCKING 3 3 Auto escape void escape void escape auto int result_in degrees 0 double radians if distanceRight gt distanceLeft calculate alpha angle result in radians radians atan2 distanceRight distanceLeft convert from radians to degrees result in degrees radians 180 M 1 PI calculate the escape angle degrees escape 135 result in degrees rotate the desired angle for escape rotate 40 RIGHT degrees escape BLOCKING move forward and with the selected speed changeDirection FWD moveAtSpeed speed correction speed writeString PC TURN RIGHT n show in terminal distance stop distance l 72 elsif else Interactive Ultrasonic Guided System distanceRight lt distanceLeft this is the same as the previous loop but it is used when the left distance is larger than the right one vadians atan2 distanceLeft distanceRight result in degrees radians 180 M 1 PI degrees escape 1
55. stem 3 2 Hardware The implementation of this project does not require complex hardware since all the external components needed are connected via the I2C bus These components are the LCD display the keypad matrix and the ultrasonic sensor The robot is connected to the PC using a UART to USB interface which is used for programming the microcontroller and for receiving data from the robot All the physical connections are explained in detail in chapter 6 2 3 2 1 The PC Bus 2 E The 12C bus is a serial communication protocol designed by Philips at Figure 3 3 PC logo 3 the beginning of the 1980s In the late seventies the use of microprocessors in consumer electronics was increasing and Philips started to think about one new solution to save some space in the PCBs The reason was that the data communications as well as the addresses used for interconnect integrated circuits and microcontrollers occupied a large space of the board since they used the parallel communication system with a wide eight bits bus Philips researched for a low cost system that interconnects the data and address lines of the microcontroller and the integrated circuits This inter IC bus was called IIC or I C bus and it started to be implemented in systems where size and cost were compulsory and the data speed was not much important 2 USB Universal Serial Bus 2 The historical information has been t
56. t in the corresponding output The module is constantly scanning the keypad to detect changes in the keys and it reflects the changes in two registers These registers are located in the addresses one and two of the LCD module In the next table both registers are represented They indicate the key that has been ON foe O O O ROW 1 1 2 3 ROW 2 4 5 6 ROW 3 7 8 9 ROW 4 0 Table 5 Matrix keypad values pressed sorted by its position in the keypad Row Column High byte Low byte 0 0 0 O 4 3 4 2 4 1 3 3 32 3 1 23 2 2 2 1 1 3 1 2 I 1 0 0 0 0 0 9 8 7 6 5 4 3 2 1 When one key is pressed the corresponding bit in the register will be in high state This information is included in the Technical Documentation 5 Table 6 Registers used by the matrix keypad 5 37 Interactive Ultrasonic Guided System 6 Results This chapter explains all the work done in the project It includes the hardware built the developed software and the tests done 6 1 Final results The result obtained is a system that avoids objects with two different strategies A menu is showed in the LCD display and the user can choose which strategy prefers to use with the help of a keypad The first strategy is called Automatic mode In this case the robot stops at a predetermined distance from the obje
57. te Not available 2 Keypad state High byte Not available 3 Version Not available Table 3 Registers of the LCD display 5 The register number 0 is the only one that has a double purpose since it can be read or written In written mode this register takes the commands for the LCD display When it is read it shows the number of free bits that rest in the FIFO buffer Register one and two show the status of the matrix keypad and register three shows the current version of the LCD software 35 Interactive Ultrasonic Guided System These are the commands that can be set to the command register Decimal Command Description 0 Null ignored Ignored as a no operation 1 Cursor Home Sets the cursor to the home position top left Cursor to a position specified by the next byte where 1 is the A Ser cursat 1 80 top left and 80 is the bottom right 3 resolu Sets cursor using two bytes where first byte is the line and the second byte is the column 4 Hide cursor Stops the position cursor from appearing on the display 5 Show underline cursor Changes the cursor to the underline type 6 Show blinking cursor Changes the cursor to the blinking type 8 Backspace Deletes the preceding character from the current position on the display 9 Horizontal tab by tab Moves the current position across by the tab space set by set command 18 default tab space 4 10 Smart line feed Moves the c
58. teractive Ultrasonic Guided System 4 3 Backlight char backlightScreen 80 PROGMEM SELECT OPTION 1 BACKLIGHT ON 2 BACKLIGHT OFF 3 GO TO MAIN MENU void backlight void write LCD backlightScreen read_keypad switch key case 1 I2CTWI transmit2Bytes LCD ADR 0 19 backlight on backlight break case 2 I2CTWI transmit2Bytes LCD ADR 0 20 backlight off backlight break case 3 break 4 4 Menu char menuScreen1 80 PROGMEM MAIN MENU 1 AUTO MODE START 2 MANUAL MODE 3 BACKLIGHT ON OFF ms void menu void write LCD menuScreen1 show menu read_keypad read selection from the keypad switch key this select the menu options case 1l predef 1 Auto mode write LCD StartScreen wait hash startExploring stop break case 2 select 2 Manual mode write LCD StartScreen wait hash startExploring stop break case 3 backlight 3 Backlight selection break TI Interactive Ultrasonic Guided System 5 Main Program 5 1 Main program char introScreen1 80 PROGMEM UNIVERSITY OF CENTRAL LANCASHIRE UCLAN 2011 PRESS TO CONT char introScreen2 80 PROGMEM EL 3990 FINAL PROJECT PRESS TO CONT char introScreen3 80 PROGM SYSTEM PRESS TO char introScreen4 80 PROGM PRESS TO CONT char introScreen5 80 PROGM PRESS TO CONTINUE a ica M INTERACTIVE ULTRASONIC GUIDED N O Z lt Il
59. that acts as a switch In the passive matrix display the columns and the rows of the matrix are the electrodes 9 Both methods are shown in the next figure Column Electrodes Peel electrod Control Electrodes gt Row Electrodes Common Counter electrode gt Signal Electrodes gt Figure 5 2 Passive and active matrix displays 9 34 Interactive Ultrasonic Guided System 5 2 LCD Display It is a passive dot matrix display with twenty characters per row and four rows 20 x 4 so it can display eighty characters at the same time Each character is composed of a 5 by 7 matrix It requires a power supply of 5 V It includes a driver circuit that gives the possibility of controlling it via I C or via serial mode The module has a mode selection jumper for choosing between the IC and the serial mode This choice must be done before switching on the device since the driver check that jumper in the starting routine The I C mode is selected when the jumper is open In this mode the data communications system is faster than the LCD can accept data so it is included a FIFO buffer of 64 bytes that stores the data the LCD cannot show until it is displayed The address of the display when it is connected to the I2C bus is 0xC6 The LCD has four registers detailed in the next table Register Read Write 0 Number of free bits in FIFO buffer Command Register 1 Keypad state low by
60. tire display is considerable high and at the beginning was a problem since there are several different screens The amount of RAM is limited and store the char arrays in the ROM is imperative In order to reach this objective and save the variables in the program memory it requires the use of the PROGMEM attribute the operation of which was difficult to understand 54 Interactive Ultrasonic Guided System A Bibliography 1 2 3 4 5 6 7 8 9 10 Arexx Engineering 2007 RP6 Robot System Manual Zwolle The Netherlands Arexx Engineering Atmel Corporation March 2005 Datasheet 8 bit AVR Microcontroller with 32K Bytes In System Programmable Flash San Jose CA USA NXP 2007 Junio 19 12C bus specification and user manual Devantech LTD SRF08 Ultrasonic range finder technical specification Devantech LTD LCD03 12C Display module technical documentation telos EDV Systementwicklung GmbH 1997 i2c bus Retrieved January 15 2011 from 12c bus http www 12c bus org Everett H R 1995 Sensors for mobile robots Natick MA USA A K Peters H Boubertakha M T Y 2010 A new mobile robot navigation method using fuzzy logic and a modified Q learning algorithm Journal of Intelligent amp Fuzzy Systems 21 113 119 Fisch M R 2004 Liquid crystals laptops and life World Scientific Publishing Company Incorporated Arexx Engineering 2007 Drehgeb
61. tp www robot electronics co uk htm srf02tech htm http www robot electronics co uk forum viewtopic php f 28 t 3 29 Interactive Ultrasonic Guided System Echo Multiple echoes Units Range reported in microseconds millimeters or inches This is the pinout of the device y Power SDA SCL Do Not Connect Oy Ground STAP ETE h s 1 amp ro Kr Figure 4 6 SRF08 back side view and connections 4 Commands atic Decimal Hex 80 0x50 Ranging Mode Result in inches 81 0x51 Ranging Mode Result in centimetres 82 0x52 Ranging Mode Result in micro seconds 83 0x53 ANN Mode Result in inches 84 0x54 ANN Mode Result in centimetres 85 0x55 ANN Mode Result in micro seconds 160 0xA0 Ist in sequence to change I2C address 165 0xA5 3rd in sequence to change I2C address 170 OxAA 2nd in sequence to change I2C address Table 2 Commands for the SRF08 4 All the information of this chapter has been taken from the Technical Specifications of the manufacturer 4 which also are included in the attached CD 30 Interactive Ultrasonic Guided System 4 5 Strategy for the object avoidance The basic requirement is that the robot must use only one ultrasonic sensor The chosen position for the sensor in the robot structure is just in the middle of the front side of the robot The strategy is based on making two measures in different points and afterwards calculate
62. ursor down one line to the position beneath in the same column 11 Vertical tab Moves the cursor up one line to the position above in the same column 12 Clear screen Clears the screen and sets cursor to the home position 13 Carriage Return Moves the cursor to the start of the next line Clears the contents of the current column and moves cursor 17 Clear Column i right by one column 18 Tab set Sets the required tab size the following byte can be a size of between 1 and 10 19 Backlight on Turns the backlight of the LCD03 on 20 Backlight off default Turns the backlight of the LCD03 off 27 Custom char generator Allows 8 custom chars to be built 32 255 ASCII chars Writes ASCII chars straight to the display Table 4 Commands for the LCD display 5 The information of this chapter has been obtained from the manufacturer s Technical Documentation 5 The complete technical documentation including detailed connections and measures is included in the CD ROM 36 5 3 Matrix keypad It is a four rows and three columns matrix keypad and in each intersection it has a switch associated to a push button The keypad is connected to the LCD module using a seven line bus Three of these lines are input signals introduced in the keypad and the other four are the outputs of each row The module sends a signal to the first column and checks if any of the Interactive Ultrasonic Guided System switches is on If this happens a signal is sen
63. uthors and contributors on those projects and all those who have contributed to Programmer s Notepad Figure 3 1 About of Programmer s Notepad 2 The version of the program was 2 0 8 and it can be downloaded at http www pnotepad org download 3 1 3 RP6 Loader It is a program developed by Arexx Engineering and it is used to upload the hex files generated with the code editor to the microcontroller on the RP6 It is not necessary to install 2 http www pnotepad org licensing 21 http www pnotepad org features Interactive Ultrasonic Guided System it on the PC since it is written in Java The program includes a terminal for monitoring the data received from the robot It has an option that allows the user check the memory status and the value of each byte in the ROM RP6 Loader G 1 Figure 3 2 RP6 Loader Screenshot Figure 3 2 shows a screenshot of the RP6 Loader The main parts of the program are 1 Selection box for choosing the connection method to the robot In this case the serial connection detailed in chapter 3 2 2 appears 2 Selection of the hex file that is going to be sent to the robot 3 Upload the selected file 4 It is possible to start and stop the robot remotely 5 This box shows the status of the robot It includes the firmware version and the updated battery voltage 6 Tabs for selecting the terminal and the memory viewer Hex Viewer 20 Interactive Ultrasonic Guided Sy
64. ve the mobility necessary To solve this problem a LCD display will connect the robot with the environment and a matrix keypad will contribute to interact with the robot 3 Activities 3 1 Work breakdown structure l Research for general information 1 1 Choosing main topic of the project 1 2 Choosing specifications Ze Progress report preparation 3 RP6 Robot System Silk Literature review and researching 3 2 Research about its motion system 3 3 Programming robot microcontroller 3 4 Test of motion system 4 Ultrasonic guided system 4 1 Literature review and researching 56 Interactive Ultrasonic Guided System 4 2 Choosing kind and number of sensors and object avoiding strategy 4 3 Designing electronic circuit 4 4 Programming robot microcontroller 4 5 Test of ultrasonic guided system 5 LCD display system 5 1 Research about LCD displays 5 2 Choose LCD display 5 3 Programming robot microcontroller 5 4 Test the LCD display 6 Overall general test T Building prototype 7 1 Add sensor and display to the robot Teak Check the connections 8 Final test of the prototype de Final report preparation 10 Preparation viva poster presentation 3 2 Task descriptions First a research on the Internet will be done to choose the main topic of the project and its specifications WBS 1 1 WBS 1 2 The first one of the reports will be a Progress Report that includes the aim of the project the initial steps done fo
65. very message shown on the screen if the message fills all the characters occupies 80 bytes The Ram memory is limited to 2048 bytes which is not enough for all the messages and the 42 Interactive Ultrasonic Guided System rest of variables that need to be stored in this memory Therefore the message arrays must be saved in the program memory To ensure that the variables are stored in the correct place the macro PROGMEM must be added after the declaration of a variable After that every time the variable needs to be used it has to be called by using its address not its variable name To get the address of the variable the symbol amp has to be added before it 6 3 1 5 math h There is only one function taken from this library It is called atan2 x y and it calculates the arctangent of an angle between the x axis plane and the point located in the coordinates x y 6 3 2 LCD display and Matrix keypad functions 6 3 2 1 Blinking code in page 68 The objective of this function is making the backlight of the LCD blink when an object is detected 6 3 2 2 Initialize cursor code in page 68 This function cleans the screen and set the cursor in the first position of the first line In addition it hides the cursor 6 3 2 3 Write LCD code in page 69 The LCD display has 80 characters and the purpose of this function is sending them to fill the screen For more information read GCC and the PROGMEM Attri

Sergio Zapatel Interactive Ultrasonic Guided System

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