An Eleague Robocup Platform
Contents
1. The maximum blob separation for the two blobs of an object s fiducial ident max sep 0 1 object 4 is an orange ball notice that ident 4 class 1 is left out ident 4 class 0 5 object 0 has a green and blue fiducial ident 0 class 0 0 ident 0 class 1 4 object 1 has a green and red fiducial ident 1 class 0 0 ident 1 class 1 2 object 2 has a red and blue fiducial ident 2 class 0 2 13 ident 4 obje ident ident NOTE Two Thi D 1 2 3 4 5 2 class 1 4 ct 3 has a yellow and blue fiducial 3 class 0 3 3 class 1 4 teams of four robots and one ball would require 9 object declarations S configuration file was created for one team and a ball References Andrew Howard Mezzanine User Manual http playerstage sourceforge net mezzanine mezzanine html 2002 John Anderson Jacky Baltes David Livingston Elizabeth Sklar and Jonah Tower Toward an Undergradiate League for Robocup 2003 Michael Bowling and Manuela Veloso Motion Control in CMUnited 98 Robocup Technical Committee Sony Four Legged Robot Football League Rule Book 2003 Janez Per and Stanislac Kovai Nonparametric Model Based Radial Lens Distortion Correction Using Tilted Camera Assumption 142. sasra sarea serre serco 7 S IR Transmitter aesa eee DE A SES DE Ae ELA AR v 7 5 FASsembly Notes Gades quw soins aeaa CUT Bele bees MAUS kb 8 S BrickOS Firmware oee na b e AVA PADE ues adhe Six eae ae 8 10 Conclusion System Evaluation sanaa saraa aaraa earar eeuu 8 A Installation Instruction 484408 adem saana UR Y RKA Rika ced ELS 9 B Runtime Instructions sues sasas ue ap A La ets nM ios sod 9 C Sample qmezzanrDe OpE uibem cp REN d RA dex ue EXON Gaxtes 10 References 212a Qi ROY WARIATUR e eus e eur hace a Glee 14 Introduction The collection of hardware and software described in this paper provide a platform for robotic soccer programming System requirements x86 PC approximately 700mhz Linux and all the basic development tools Video4Linux compatible capture card and V4L enabled kernel see http www video4linux net for details Color video camera Third party libraries for mezzanine GTK 1 2 or better and GSL 0 9 or better Lego RCX based robots IR transmitter see section 8 brightly colored fiducials and plastic ball 2 System Architecture d VAL library UDP reception command Pow cm A server mezeanine motor m pue broadcast N i i i Object data packer I Object data memory mapped yel v vn 232 file A Theoretical TS SOFTWARE HARDWARE IR u xmitter fiducials S Robot 0 fiducials camera
3. 130 vypoly 1 112 72 vypoly 2 123 191 vypoly 3 81 160 name pink color 255 105 180 vupoly 0 216 167 vupoly 1 229 164 vupoly 2 223 191 vupoly 3 193 189 yupoly 0 97 183 yupoly 1 73 187 yupoly 2 66 168 yupoly 3 9 6 113 vypoly 0 226 202 vypoly 1 204 196 vypoly 2 193 208 vypoly 3 222 222 name red color 255 0 0 vupoly 0 180 96 vupoly 1 56 108 vupoly 2 162 136 vupoly 3 215 120 yupoly 0 188 105 yupoly 1 183 132 yupoly 2 120 122 vupoly 3 52 152 yupoly 3 25 106 vypoly 0 51 1860 vypoly 1 59 199 vypoly 2 206 131 vypoly 3 173 80 name yellow color 255 255 0 vupoly 0 155 79 vupoly 1 157 107 vupoly 2 125 114 vupoly 3 131 82 yupoly 0 193 72 yupoly 1 159 124 yupoly 2 239 135 yupoly 3 227 90 vypoly 0 123 239 vypoly 1 126 195 vypoly 2 186 128 vypoly 3 200 142 name blue color 0 0 255 vupoly 0 122 156 11 classify class 4 vupoly 1 122 131 classify class 4 vupoly 2 160 120 classify class 4 vupoly 3 152 152 classify cl
4. 141 188 113 80 134 115 157 10 00 0 a Qv Qo OQ QcQo d ed la Ov OO G Qr oo Qv CO ou Ob OA AMO r Qv Q Q Qo Q QQ TE AA Oo A 2 CA lassify lassify lassify lassify Q Qo Q A lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify Qi QcQ o9 occ mq o cQ oo lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify Q Q Q OQ 0 0 LO LA Q Q lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify lassify 0000000000 0 0 a A lassify Q Q lassify lassify Q lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass lass Bs O O o NNNNNBNNNNNNDNDN DN V WU U WWW WWW WWW WU WWW Ww vypoly 0 57
5. 3 TestAI also has a useful motor testing mode that does not require the video server to be running 7 gage TestAI listens for data on port 6363 and transmits motor commands on port 6364 optional commandline parameters for TestAI are step Wait for user input before proceeding to issue the next set of instructions to the robots verbose Verbose output naive Use a naive motion algorithm instead of CMU s complex algorithm The naive algorithm moves forward if the robot is roughly facing the ball Otherwise the robot spins 1n place test 0 0 1 0 Enable motor test mode In this mode the user enters a motor command followed by the enter key to command all of the robots This 6 mode is useful for testing the robots the command server and the IR transmitter test must be the first argument passed The motor commands are as follows 5 forward 2 backward 1 z turn left 3 z turn right on the keyboard s number pad these form the familiar upside down T Optionally the user may pass a floating point number 0 0 1 0 to indicate what motor power level to use The default is 1 0 full power TestAI is intended to be a model for teams to base their own more complex robot control programs on It might also be useful to adapt it into a an eleague user API 7 Motor Broadcasting command server The command server continually sends robot motor comma
6. OQ Eg Robot 1 ball 3 Camera Any camera that outputs a composite or s video signal should work However it is important to consider the viewing angle focal length when choosing a camera Fitting the entire pitch withing the camera s field of view may necessitate using a wide angle lens Cheap color video cameras with built in wide angle lenses can be purchased for less than 100 We used an X10 wireless color camera Wide angle lenses exhibit barrel distortion This type of distortion makes the image appear bulged outward in the middle Our need to correct this distortion is what motivated our adoption of Mezzanine for tracking Mezzanine has barrel distortion correction built in 5 4 Mezzanine Package Mezzanine is an overhead camera 2D vision tracking system that uses Video4Linux as a video source Objects are marked with uniquely colored fiducials that Mezzanine searches for when trying to locate the objects Mezzanine s configuration file mezzanine opt 1s located in the user s home directory This file stores object and color definitions as well as the dewarp grid Setup instructions and documentation for mezzanine can be found at the project s website http playerstage sourceforge net mezzanine mezzanine html 4 mezzanine Video Server mezzanine is the program that does all of the video processing and object identification 4 1 1 Algorithm Overview load user s configuration from mezzanine opt build the image
7. contrast 35 Image mask defined in mezzcal this limits the area of interest No pixels outside of this boundary are considered classify mask poly 0 607 216 classify mask poly 1 598 127 classify mask poly 2 578 33 classify mask poly 3 519 17 classify mask poly 4 430 9 classify mask poly 5 304 11 classify mask poly 6 180 23 classify mask poly 7 73 51 classify mask poly 8 47 168 classify mask poly 9 42 213 classify mask poly 10 39 265 classify mask poly 11 57 390 classify mask poly 12 172 417 classify mask poly 13 276 429 classify mask poly 14 363 433 classify mask poly 15 455 428 classify mask poly 16 572 409 classify mask poly 17 598 282 Color Definitions th color name is entere this is the rgb color us classify class 0 color The color space polygons classify class 0 vupoly 0 classify class 0 vupoly 1 classify class 0 vupoly 2 classify class 0 vupoly 3 classify class 0 yupoly 0 classify class 0 yupoly 1 classify class 0 yupoly 2 classify class 0 yupoly 3 d manually classify class 0 name green ed to denote this color class in mezzcal this is also entered manually Oy 7255 0 were set using mezzcal 126 111 120 144 71 160 70 137 182
8. to world coordinates transformation loop for each video frame grabbed from VAL color classify Examine each pixel in image Ifit fits one of the user s color definitions then assign that color to the pixel find blobs Identify groups of adjacent identically colored pixels as blobs find objects For each object fiducial definition try to find a matching pair of adjacent blobs Record the position angle and velocity of the object send a signal indicating that new data is ready Weare using Mezzanine as a robot and ball location server for eleague To fill this role a few changes had to be made to Mezzanine as follows 4 1 2 Changes made 1 Support for distinct objects Mezzanine originally supported the definition of and tracking of only one type of object For eleague soccer at least three distinct objects must be tracked the ball and two different teams Distinguishing between each member of a given team may also be desired if static roles are to be assigned especially for a goalkeeper The new syntax for object definitions is ident i where iis the object number starting with zero This change applies to section 3 5 5 of the mezzanine manual 1 instead of defining a single object ident class 0 0 ident class 1 1 we now define multiple objects ident 0 class 0 0 ident 0 class 1 2 ident 1 class 0 1 ident 1 class 1 4 ident 2 class 0 3 2 Supp
9. 500 dewarp wpos 2 0 000 0 500 dewarp wpos 3 0 500 0 500 dewarp wpos 4 1 000 0 500 dewarp wpos 5 1 000 0 000 dewarp wpos 6 0 500 0 000 dewarp wpos 7 0 000 0 000 dewarp wpos 8 0 500 0 000 dewarp wpos 9 1 000 0 000 12 dewarp wpos 10 1 000 0 500 dewarp wpos 11 0 500 0 500 dewarp wpos 12 0 000 0 500 dewarp wpos 13 0 500 0 500 dewarp wpos 14 1 000 0 500 dewarp wpos 15 0 000 0 250 dewarp wpos 16 0 000 0 250 These are the image coordinates of the above defined calibation points These were set by dragging the calibration points in mezzcal dewarp ipos 0 65 358 dewarp ipos 1 155 385 dewarp ipos 2 297 403 dewarp ipos 3 442 408 dewarp ipos 4 565 397 dewarp ipos 5 60 203 dewarp ipos 6 154 201 dewarp ipos 7 296 200 dewarp ipos 8 458 210 dewarp ipos 9 589 214 dewarp ipos 10 84 53 dewarp ipos 11 181 29 dewarp ipos 12 304 18 dewarp ipos 13 452 25 dewarp ipos 14 568 45 dewarp ipos 15 294 310 dewarp ipos 16 301 100 Object identification The number of objects ident object count 5 The maximum displacement of an object between two consecutive video frames mezzanine will only look for an object within this radius of where it was last located ident max disp 0 3
10. An Eleague Robocup Platform Stephen Tarzia 26 December 2004 Abstract This paper describes an Eleague robotic soccer platform assembled at Columbia University This platform is highly modular The most important module is a customized version of Mezzanine an overhead camera object tracking software developed at USC s Robotics Lab In this paper I describe the role of each module as well as give usage instructions and evaluate the system Table of Contents bInttoduetiOI ssr uoetine Ret ev eb Sv xx US Erde sy SR Laus 1 2 System Arch 1801ure gt as alice e X99 D TO A Ge vee ERE eis 1 J Camera c e Pelee UP KA deus Beers DRY BEL xke WEE eau 2 SPN eZzamne Package uc les mese hud Bee GA od pee 24007 ES 2 4 1 mezzanine Video Server ese sede nie caran ek he esso 2 4 1 1 Algorithm Overview sersa lee cores esco 2 4 1 2 Changes Made sao Sikes doxes esa atoque EO A aes 3 422 Mezzanine CallbraHon sz Shox p c eeu E Ene i M 4 42 1 Geometry Dewarplng obey ERE REX Gee EE 4 4 2 2 Color Definition 24 4 gcse aka Disk S e dA E Ree 4 4 2 3 Image Mask Definition soc tay oe dx yp we E sasso 4 4 3 The Mezzanine Library libmezz sasaa lese sees 4 5 State Broadcasting eleapue output UDP iuc sanaa une HA A In 5 S IChentPrntet Ji uua exu zd R RO siete RN EST week eens 5 Example User Program TestAL discs ense saran WE XE cerus 6 7 Motor Broadcasting command server
11. ass 4 yupoly 0 91 128 classify class 4 yupoly 1 167 136 classify class 4 yupoly 2 155 159 classify class 4 yupoly 3 84 145 classify class 4 vypoly 0 148 88 classify class 4 vypoly 1 152 164 classify class 4 vypoly 2 132 168 classify class 4 vypoly 3 124 96 classify class 5 name orange classify class 5 color 255 127 0 classify class 5 vupoly 0 186 78 classify class 5 vupoly 1 202 97 classify class 5 vupoly 2 145 119 classify class 5 vupoly 3 151 90 classify class 5 yupoly 0 110 89 classify class 5 yupoly 1 106 104 classify class 5 yupoly 2 201 113 classify class 5 yupoly 3 184 79 classify class 5 vypoly 0 150 203 classify class 5 vypoly 1 147 173 classify class 5 vypoly 2 200 128 classify class 5 vypoly 3 199 142 Blob finder these are the blob size constraints they will depend on the size of your fiducials and the distance of the camera These settings can be edited from within mezzcal blobfind min_area 20 blobfind max_area 250 blobfind min_sizex 5 blobfind max_sizex 20 blobfind min_sizey 5 blobfind max_sizey 20 Dewarp calibration points This defines the world coordinates of your calibation points It is best to leave these alon We map from these coordinates to the eleague coordinates in the eleague_output UDP program dewarp wpos 0 1 000 0 500 dewarp wpos 1 0 500 0
12. ly did eleague UDP and eleague output commandline arguments x length sets the pitch length in millimeters We use the identifier x because the long side of the field corresponds to the xaxis in the camera image Default value is 4600 corresponding to the Robocup legged league s field 4 y width sets the pitch width in millimeters Default value is 2700 corresponding to the Robocup legged league s field eleague UDP specific commandline arguments p port number sets the port number to listen on enable verbose debugging output 5 1 Testing with ClientPrinter ClientPrinter 1s a simple test utility for eleague UDP broadcasts It sets up a UDP socket to receive the data that is being transmitted and prints the packets as they arrive This program was provided with doraemon which uses the same broadcast format as eleague UDP 2 ClientPrinter commandline arguments p port number sets the port number to listen on 6 Example User Program TestAI TestAI is a simple C example robot control program This code is based on Jake Porway and Gaurav Singal s eleague 2004 code It receives the object position data from eleague UDP and sends robot instructions to command server The program simply instructs each robot to attempt to score a goal by moving to the location of the ball with an approach vector pointing at the left hand side goal CMU s differential drive motion algorithm was used for this
13. nd then flash it onto the PIC Be sure to use a null modem cable to connect the transmitter to your computer the gray cable included with the Lego R5232 Tower will work You should use a male 9 pin D sub connector on the board Be sure to match the series forward voltage of your LEDs with the voltage of the power supply Check your LED s specifications for this specification If the voltages are matched then you should short the IR pod jumpers to cut out the resistors If the voltage of the power supply is higher than the operating voltage of the series LEDs then leave the jumpers open to lower the voltage supplied across the LEDs 9 BrickOS Firmware In order to understand the commands sent by command server each robot s RCX must be loaded with BrickOS firmware and Jacky Baltes uleague BrickOS program These steps are both done using the BrickOS firmware sh script Ifthe RCX has BrickOS loaded it will not beep when turned on To activate an RCX turn iton and push the run button Once running the digit on the screen indicates which robot itis acting as To change this number press the programbutton To turn off the RCX first press run to disable it and press power to turn it off If the batteries are taken out for more than a few seconds this procedure will need to be repeated as the RCX s program memory is volatile 10 Conclusion System Evaluation The system described in this paper is fully functional though it is not without sh
14. nds to the IR transmitter These motor commands are updated by the team Alprograms by sending an ASCII message to command server through the specified port This program was written by Jacky Baltes and is part of the uleague package 2 command server commandline arguments p port number sets the port number to listen on 8 IR Transmitter command server is designed to work with either the RS232 or USB Lego IR Tower These are omni directional devices with a transmission range of several feet In order to transmit motor commands to all of the robots on a large pitch a high power IR transmitter must be used instead We built one using Jacky Baltes schematic and PCB For transmission it is plug and play compatible with the Lego RS232 Tower This transmitter does not have reception capabilities it only transmits For this reason when doing Lego RCX firmware updates the standard short range Lego IR Tower must be used Vsupply 4A PC PIC Power LED rs232 1 UU transistor pods 8 1 Assembly Notes You may only need to use the large pod to transmit across the entire pitch It you end up with dead zones then use the small pods as well The most sophisticated part of the assembly 1s programming the PIC microcontroller Your EE department should be able to provide you with a PIC programmer and software for this task Just cut and paste the code provided a
15. ort for single blob objects Mezzanine originally only supported two blob objects This of course would not work for tracking a ball Single blob support was added for this reason The user may simply omit the declaration of a second color class for any object to make it a single blob object Since single blob objects are radially symmetric the notion of a pose angle does not apply Therefore single blob objects are assigned a zero angle Internally a single blob object s second color is assigned NULL COLOR MAX INT In the example above object 2 is a single blob object of color class 3 3 Brightness and Contrast control Brightness and contrast control from within mezzanine opt was added because I found that adjusting these settings can improve color saturation and lead to easier distinction between colors The syntax is fgrab brightness 0 100 fgrab contrast 0 100 4 2 Mezzanine calibration with mezzcal mezzcal provides an easy to use graphical interface for configuring some aspects of Mezzanine The following three settings can also be configured manually by editing the mezzanine configuration file but they are much easier to set using mezzcal 4 2 1 Geometry Dewarping See the mezzanine manual section 4 2 4 for details I found that for lenses with significant amounts of barrel distortion the calibration points had to be set very carefully in order to avoid bogus image to world mappings Irecommend measuring o
16. ortcomings Most notably mezzanine dewarp calibration is less than perfect and the UDP broadcast implementation is prone to network flooding Overall though the system is quite workable A Installation Instructions Installation is a five step process l Compile the source code From the top level package directory make Optional move the compiled binaries to a system directory We will assume that this is not done Write a configuration file and name it mezzanine 0 00 etc mezzanine opt An example is included in Mezzanine examples mezzanine opt See section 4 1 2 and the mezzanine manual for details Adjust the configuration file using mezzcal See section 4 2 for details Load the firmware onto the Robots S BrickOS firmware sh B Runtime Instructions This section describes how to run a complete test of the system using the TestAI code l start mezzanine Mezzanine mezzanine mezzanine start eleague output program eleague output eleague UDP p 6363 start the command server command server command server p 6364 start the AI program TestAI TestAI verbose start the robots Turn on push run push programto set each robot s number C Sample mez mezzanine 0 00 etc mez fgrab offline 0 fgrab norm ntsc Image size to work with fgrab width 640 fgrab height 480 zanine opt zanine opt normal brightness and low contrast fgrab brightness 50 fgrab
17. ut the calibration points on the pitch and marking them rather than just trying to do it by eye It is easy to tell if your dewarp grid is inaccurate In this case the blue object squares will be offset from the actual location of the corresponding fiducial 4 2 2 Color Definition See the mezzanine manual section 4 2 2 for details Calibrating the color definitions is a long iterative process Uniform lighting on the pitch is essential Also the fiducial colors must be very bright unless you are using an an expensive camera 4 2 3 Image Mask Definition See the mezzanine manual section 4 2 1 for details This is a straightforward procedure 4 3 The Mezzanine Library libmezz libmezz is an IPC library that allows a program to access the data stored by mezzanine Most notably this includes the poses of all of the objects This is facilitated by a shared memory mapped file This library is what makes Mezzanine such a versatile platform eleague UDP uses this library 5 Object State Broadcasting eleague output UDP eleague output and eleague UDP are simple programs that broadcast the robot and ball data in the uleague format 2 They use libmezz to retrieve this information from Mezzanine eleague output writes to stdout while eleague UDP broadcasts using a UDP socket Our network admin complained about the network flooding eleague UDP was causing so use it at your own risk be sure not to leave it running overnight as I accidental
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