e-puck Ground Sensors User`s Manual
Contents
1. User s Manual Version 21NOV07 Canada Inc Ottawa Canada Table of Contents l DESCRIP HON OF the I alee si a aoe 3 Bas FOES GT FUE rae aarti mb e udin betur 3 1 2 Enc WING ooi E S 4 OF Fal eo ee qu 4 4 Surface eray Ievel 5 WSOC ANN ZA Oae 5 2 Installing e puck Ground Sensor scccccccccccccccccccaceccensssssseseceecccccccecseesaaaeaganssssseeees 6 De Lest Progr IM 9 4 Adjusting the detected 9 5 The Line Tracing sample program nennen eene nnne nnne 12 241r The sample PLO CRAM 12 2 2 Making a Line Following track oe ebria epe ente bleu 15 6 e puck Ground Sensors in Webots 15 7 Controlling e puck with dai ib dle tiat 17 8 Accuracy of black and white 19 d 20 Acknowledenmient 20 c NOTOS EH 21 1 Descr2. Tera Term Serial port setup Port coms Baud rate 5200 Data abit Cancel Parity none gt Stop Help Flow control ce Transmit delay msecfchar 0 msecfline Figure 4 2 Serial port setup 4 When the connection is established you will see the welcome message shown below lel x B COM5 11520 0baud Tera Term VT File Edit Setup Control Window Help ELCOME to the SerCom protocol on e Puck he EPFL education robot type for help Figure 4 3 sercom welcome message 5 Type to get help on available commands 6 To verify if the sensor detects white colour enter M while placing the e puck a white surface If your sercom hex is version 1 1 5 or older all data you get should be negative as in Figure 4 4 If using the latest sercom hex version 1 1 6 as in Figure 4 5 the data should be around 950 G_COM5 9600baud Tera Term VT IN ici xt File Edit Setup Control Window Help sili ioa wor SB ion BUB COM5 115200baud Tera Term YT File Edit Setup Control Window 756 960 960 756 960 960 956 961 9 Figure 4 5 White surface detection with sercom version 1 1 6 7 To verify if the sensor detects black colour enter M while placing the e puck on a black surface Printed black ink may not be detectable data you get should be positive as in Figure 4 6 _COM5 9600baud Tera Term Bl
3. 2 Re connect the motor connector at JM1 3 Insert the Ground Sensors module in the vertical slot at the front of the e puck s plastic base When installing the module make sure the face of the 3 active IR sensor elements points downward and the module s CPU is mounted to face outward as shown in Figure 2 2 Use tweezers if necessary and extra care when working with the connectors of the Ground Sensors module and the motor E ui z wo gt Cu zji d z T ar Tu Pal E L Mi E D iom P E og OU it cu Ub d E CN ci A p P E m tert s T UU cu lt gt m irr Hot M v cx i i h T T d gd ya T Es y 2 s de HM 2 EN fim a Eg ET B n g LAR a n T iu F T um i i gy um Ms P i iue X LL ant RE ea E k EO Ls L Oe e M Figure 2 2 Front of the e puck with a Ground Sensors module installed 3 Adjustment After inserting the Ground Sensors module completely adjust its seating so that its bottom edge sits parallel to the floor 4 Reassembly After the adjustment put everything back together 3 Test Program Test program advance sercom will enable you to read the detected values from the sensor elements of Ground Sensors 1 Download the
4. from drop down menu at the e puck interface window 6 Turn off the e puck power switch Figures 7 3 and 7 4 illustrate an e puck robot running in follow line mode Front LED will be on when the robot follows the line A side LED will be on when the robot follows an obstacle Figure 7 3 e puck follows obstacle Figure 7 4 e puck follows line 8 Accuracy of black and white detection With the sercom hex program version 1 1 5 or later e puck Ground Sensors detects black and white colour very accurately as shown below in Figure 8 1 Please note that sercom hex version 1 1 5 is used for this test and the values for white colour detection in the graph are negative Accurate detection makes line following performance smooth and stable Black amp White detected value log 200 200 times of Ground Sensor White color detection 200 times Black color detection 200 times 400 d 350 M 250 200 e Sensor1 Left mB8 Sensor2 Middle Sensor3 Right 150 Detected Value 50 Experimental Run Figure 8 1 Black and white detection by the Ground Sensors 9 Support If you need support in introducing or using AAT s e puck Ground Sensors please contact AAI Canada Inc at Tel 1 613 839 6161 Fax 1 613 839 6616 Email info AAI ca We will answer questions concerning the sensor s specifications installation and use Acknowledgment The e puck Ground Sensors was developed at th
5. state 0 oam reset 0 LLM O inibit amp 0 OFM 0 LEM O state O oam reset 0 v Qi WorldInfo Viewpoint 294 m4095 3388292 Backerourid 4095 1795 Switching to SIMULATION and reseting all BB variables PointLight 915 364 817 PointLight 428 27 DEF WALL Solid amp E E E En EO Ee E EO 1 1 2 s Q DEF GROUND Sa DEF GROUNDBO d 1 2 Pree iei m2 Ww De amp Do Gd Lin e LL Ls Si a Figure 7 1 Line following demo running in Webots 17 1 Stop running in simulation mode by clicking on the stop button On e puck interface window select the correct COM port associated with your Bluetooth Then choose remote control from the first drop down menu Once connected the version of serial communication software will be displayed as shown in Figure 7 2 aaa e puck fremote control 179 290 97 m3880 3837m 1 3843 246 H gg 382r 0 Running real e puck Version 1 1 6 June 2007 Figure 7 2 e puck interface window 2 Click on run button to run the e puck remotely Webots reads the data proximity light Ground Sensors camera image coming from the actual e puck and sends motor commands to the real robot 3 Your e puck will start following the line 4 To stop it simply click on stop button on the e puck_line_demo wbt window 5 Select simulation
6. c gt c DO NOT DISTRIBUTE THIS SOURCE CODE P IT IS OWNED BY jean christophe zufferey epfl ch 3 5 HEH 3 3 3 3 3 3 3 3 3 3 9 3 3 7 8 include device robot h 9 include lt device differential_wheels h gt 10 include lt device distance_sensor h gt 11 include device light sensor h 12 include device led h 19 14 77 Global defines 15 define TRUE 1 16 define FALSE 0 17 define NO SIDE 1 18 define LEFT 0 19 define RIGHT 1 20 define WHITE 0 21 define BLACK 1 22 define SIMULATION 0 27 for 23 define REALITY 2 dafina TIME 29 DU DES lil 1 03x aaah smuston Welcome to Webots 0 00 02 624 Scene Tree Xx m o5 13 Sc e puck 305g I e puck OAM side 4095 OAM 0 side DEF OBSTACLE OAM 0 side DEF OBSTACLE e puck OAM side j OAM 0 side LLM O inibit amp 0 OFM LEM O state 0 oam reset 0 LLM O inibit amp OFM O LEM O state oam reset 0 LLM O inibit amp OFM LEM O state 0 oam reset 0 LLM O inibit amp OFM O0 LEM
7. e puck svn snapshot from http www e puck ore index php option2com remository amp Itemid 7 1 amp func select amp id 7 If above link does not work go to www e puck org then DOWNLOAD gt SOFTWARE gt LIBRARY 2 Unzip and load sercom hex onto the e puck 3 Download TeraTerm free of charge from http ttssh2 sourceforge jp or HyperTerminal payment required from http www hilgraeve com htpe index html and load it onto your PC which has a Bluetooth function If you are using Windows 95 NT4 0 98 98 SE ME Windows 2000 or XP HyperTerminal program is included as part of the operating system 4 Adjusting the detected position To determine the best position of the reflective active IR sensor elements we describe the procedure using Tera Term as an example 1 Turn on your e puck and start TeraTerm on your PC Make sure to register your e puck as a Bluetooth detection tool on your PC before starting 2 On the New connection screen choose Serial and the COM port number e puck assigns Click OK Verify if the orange LED of the e puck turns on 3 Click Setup from the menu bar and then Serial port Confirm that the settings are the same as shown below Click OK Tera Term connection C Host 192 168 1 3 M History Service Telnet aW ge E f SSH 55H version SSH2 C Oth E Protocol UNSPEC Cancel Help Figure 4 1 New connection with Tera Term
8. xl File Edit Setup Control Window Help 285 248 263 285 249 263 285 249 263 um Figure 4 6 Black surface detection 8 If the values you get are not as they should be adjust the position of the Ground Sensors module and repeat the above test until you get appropriate values It is necessary to maintain approximately Imm between the object and the sensor elements for proper detection 5 The Line Tracing sample program 5 1 The sample program By choosing the trace line mode in the program the robot can follow a black line drawn on the white background e g white paper while avoiding obstacles found in its way and return to its track after disruption A sample program for a simple line tracing is shown below for your reference 1 Create runlinetracer c in the program Wemo Memo swis 1 folder 2 Add the runlinetracer c you created to the DemoSwis1 project 3 Copy the program code below into runlinetracer c 4 Add CALL processing of the run linetracer to the branch method process according to selector number in the c c 5 Compile above project and load it to the e puck runlinetracer c Program Line tracing program for the e puck equipped with a Ground Sensors board include p30f6014A h Hinclude library motor led e init port h Hinclude library motor led e motors h Hinclude library motor led e led h Hinclude libra
9. ce of the robot s experimental arena so that e puck s on board software can interpret such patterns to localize its present position 2 Installing e puck Ground Sensors Caution The warranty is void if the e puck and or associated parts are disassembled or modified by user in a manner other than shown below 1 Disassemble the e puck Remove the battery from the bottom Dismount the extension board from the plastic body as described below Make sure not to remove the wheels from the motor axles during installation of the Ground Sensors In case you do remove the wheels pay extra attention when replacing and tightening the wheels The built in link gears in the motors are very fragile and they may break if tightened too much When fastening the wheels with the nuts use light torque while making sure it is not too loose allowing the motor to spin free Steps to dismount the top extension board and e puck s main PCB from the chassis CD Remove the battery from the bottom 2 Unscrew three screws circled in red 3 Dismount the speaker extension board 4 Unscrew the three hex standoffs circled in red 5 Remove plastic ring from the plastic body 6 Dismount the PCB from the plastic body 7 Remove the motor connector from JM1 large red rectangle in Figure 2 1 in Page 8 2 Installation of the Ground Sensors module CD Connect the connector for Ground Sensors module at JBO small red oval in Figure 2 1 in Page 8
10. e Laboratory of Intelligent Systems LIS of EPFL by Adam Klaptocz and Jean Christophe Zufferey under the leadership of Professor Dario Floreano http lis epfl ch They contributed to Section 1 of this document as well as the development of the initial version of the line following list program Dr Olivier Michel of Cyberbotics SA provided support in running and testing the line following simulation in Webots Drs Jean Christophe Zufferey of cole Polytechnique F d rale de Lausanne s Laboratory of Intelligent Systems Olivier Michel of Cyberbotics S r l Gilles Caprari of GCtronic and Francesco Mondada of Mobile Robotics Laboratory of EPFL all contributed to improve this document The sample line following program shown in 5 1 was written by Masayuki Karasaki of Kodai HiTec Co Ltd in Japan 20 References 1 Bio Inspired Adaptive Machines course at EPFL http moodle epfl ch course view php 1d 216 2 Line following exercice at EPFL http moodle epfl ch mod resource view php id 13709 3 Chris Cianci s home page at EPFL http www5 epfl ch swis page1339 html 4 Mobile Robots course at EPFL http moodle epfl ch course view php id 261 5 Floreano D and Mondada F 1996 Evolution of Homing Navigation in a Real Mobile Robot IEEE Transactions on Systems Man and Cybernetics Part B Cybernetics 26 3 396 407 6 Floreano D and Urzelai J 2000 Evolutionary Robots with on line self organization and behavioral fit
11. e puck to the number assigned for the line trace 2 Turn on your e puck 3 Place your e puck on the black line and it should be able to follow the black line If it does not operate well set the acceptance value 100 to smaller than 100 in the 1_buffer gt 100 line to detect and determine black colour of the program 6 e puck Ground Sensors in Webots simulator Webots is a standard 3D robot simulator developed by Dr Olivier Michel of Cyberbotics S r l www cyberbotics com The e puck line controller program contains the source code for a simple line tracing system which as an exercise can be improved upon to obtain the behavior demonstrated in the e puck line demo wbt demo In this demo the simulated e puck robot is able to follow a black line but also to leave the line if it encounters an obstacle placed on the line it is tracing The e puck would wall follow the obstacle until it circumvents it and reaches the line on the other side of the obstacle See Figure 6 1 obstacle detected Figure 6 1 Trace line and Follow obstacle modes in program e e puck line wbt Webots 5 1 9 nmx e e puck line demo wbt Webots 5 1 9 nmx File Edit Simulation Wizard Window Help File Edit Simulation Wizard Window Help DD Dy 0 00 16 128 0 86x 7 0 00 08 992 0 9 Figure 6 2 3D simulation www cyberbotics com The controller in Webots uses Subsumptio
12. er files for the Ground Sensors can be found at www e puck org Download gt HARDWARE gt EXTENSIONS gt GROUND SENSORS The e puck Ground Sensors can be used for several different applications such as 1 following a black line on a white surface 2 surface or fall detection below the robot 3 gray scale detection and 4 localization Figure 1 3 Three active IR sensor elements Vishay s TCNT1000 are spaced out along a horizontal line 1 2 Line tracing Because of their location near the front of the e puck and the lateral spacing between the 3 sensors they can be easily used to trace a black line on an otherwise white surface The line simply needs to be smaller than the distance between the two external sensors 12mm A simple algorithm can command the motors in a way that keeps the middle sensor above the black line while the external sensors detect the white space to either side This algorithm 15 currently being used in a student exercise in the Bio Inspired Adaptive Machines course taught by Prof Dario Floreano at EPFL 1 2 1 3 Surface or fall detection The Ground Sensors can also be used to detect the edge of the surface on which the e puck 15 run such as a table The ground below the edge of a table top reflects much less light than the table directly below the robot This is especially useful in case there are no solid boundaries defining the robot s experiment arena Figure 1 4 shows an example of this application o
13. f the Ground Sensors as used by Chris Cianci s experiment at the Swarm Intelligent Systems Group of EPFL Multiple e pucks are run on the surface of a table for specific swarm intelligence research 3 The four edges of the table are marked by black tape which tells e puck a boundary is reached Since no walls are involved in delineating the arena experiments can be run without having to be concerned with reflection of IR signals e puck s standard proximity sensors emit thus simplifying e puck s on board processing Figure 1 4 Surface or fall detection 1 4 Surface gray level detection The e puck Ground Sensors is currently used for a student exercise in the Mobile Robots course taught by Jean Christophe Zufferey and Dario Floreano at EPFL 4 as a device to differentiate gray levels on an arena s surface Figure 1 5 In this case the e puck moves along a bar code and the ground sensors are used as an input to the measurement model in a Markov localization process Very similar sensors 00 used many times in the field of Evolutionary Robotics by Prof Floreano Black or gray areas were painted on an otherwise white ground The robot a Khepera at the time could easily distinguish in which region of the environment it was using the intensity value returned by the ground detecting sensors 5 6 Figure 1 5 Arena used for surface gray level detection 1 5 Localization A series of black and white patterns can be drawn on the surfa
14. iption of the sensor 1 1 Basic structure The e puck Ground Sensors extension was designed and developed at the Laboratory of Intelligent Systems LIS at Ecole Polytechnique F d rale de Lausanne EPFL in Lausanne Switzerland by Adam Klaptocz and Jean Christophe Zufferey under supervision of Professor Dario Floreano The sensor is comprised of three active infrared IR proximity sensors placed in the front of the e puck miniature robot pointing directly at the ground These sensor elements are mounted on a small printed circuit board PCB which is placed in the vertical slot at the front of the e puck s plastic base The PCB also includes a microcontroller that continually samples the IR sensor elements The values obtained by the sensor elements and formatted by the microcontroller can then be read by the e puck through the I2C serial interface e puck robot 4 microcontroller IR sensor elements Figure 1 1 Connection between e puck and the Ground Sensors extension board One IR sensor element consists of an IR emitting diode LED and a phototransistor The infrared LED is used to emit a constant amount of infrared beam whereas the phototransistor simply detects the amount of signal reflected by a surface A white surface reflects much more infrared signal than a black surface as will a surface closer to the sensor element as opposed to one that is farther away Detailed schematics and PCB Gerb
15. k the center sensor and set the speed of the motors accordingly if l buffer 1 gt 200 e set speed left 300 e set speed right 300 e set body led 1 e set led 8 1 wait t 50000 check the left sensor and set the speed for the motors accordingly else if I buffer 0 gt 200 e set speed left 500 e set speed right 500 e set body led 0 e set led 8 0 wait t 50000 check the right sensor and set the speed of the motors accordingly else if I buffer 2 gt 200 e set speed left 500 e set speed right 500 e set body led 0 e set led 8 0 wait t 50000 if the line being tracked is lost set the speed of the motors to spi elsel e set speed left 500 e set speed right 500 e set body led 0 e set led 8 0 wait t 50000 5 2 Making a track for line tracing Draw a black line on the white surface Some tips for making the track are described below a If using paper white slick paper suitable for colour printing is recommended b If using a pen to draw lines black permanent marker is recommended c Black lines printed in grayscale on plain papers may not be detectable by the sensor d If using a printer high resolution colour print on slick paper is recommended e Avoid over printing on the same paper because it may cause printers to malfunction f The thickness of the line must be about 18 mm When the track is ready 1 Set the rotary switch of your
16. n Architecture to simulate the above mentioned line following behavior Figure 6 3 shows the software structure OFM Obstacle Following Line Entering Line Leaving lem speed Floor sensors OAM oam side Obstacle oam speed gt Avoidance Line Following Figure 6 3 Software architecture for following line EPFL IR sensors 16 7 Controlling e puck with Webots e puck has a Bluetooth interface allowing it to communicate with Webots In order to use Bluetooth to communicate remotely with a real e puck make sure you have already paired your e puck with your computer To run the above line follow demo remotely on a real e puck through Webots follow the steps shown below 1 Load the bootloader to the e puck using ICD2 programmer debugger 2 Load firmware 1 1 5 or later to the e puck using tiny bootloader 3 Place your e puck on a surface with a line and obstacle s 4 Turn on your e puck 5 Run Webots application version 5 1 13 or later 6 Open e puck line demo wbt as shown in Figure 7 1 Once the Bluetooth connection is properly setup the Bluetooth connection must appear in the second popup menu of the control window e puck line demo wbt Webots 5 1 13 C Program FilesfWebotsYprojectsfrobotsYe puckYXcontroll See File Simulation Wizard Tools Help b gt gt e puck_line_dermo
17. ness Neural Networks 13 431 443 21
18. ry 12C e 126 protocol h Hinclude library uart e uart char h define uart send static text msg do e send uart char msg sizeof msg 1 whi le e uart1 sendingO while 0 def ine uart send text msg do e send uart1 char msg str msg whi le e uart1 sendingO while 0 void wait t long long 1 for 120 i lt num i Start line tracing routine void run linetracer int i char buffer 30 int _buffer 3 unsigned char 12 address nit sensors e init nit motors e init motorsQ initialize UART to 115200 Kbaud e init uartl1O set the Ground Sensors 12C address and initialize 12C 126 address OxD4 e i2cp init Q Loop while 1 enable 120 e i2cp enable Q read sensors value through 12C byte by byte for i20 i lt 6 i buffer i e i2cp 126 address are read through the robot disable 126 e i2cp disable combine high and low bytes to make red value of sensor reading which 126 buffer 0 unsigned int buffer 1 unsigned int buffer 0 lt lt 8 buffer 1 unsigned int buffer 3 unsigned int buffer 2 lt lt 8 buffer 2 unsigned int buffer 5 unsigned int buffer 4 lt lt 8 send the sensor s value to the user through UART1 sprintf buffer m d d d r n buffer 0 buffer 1 _buffer 2 uart send text buffer chec
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