k213 vision turret
Contents
1. Figure 1 Overview of the turret layout Make an external inspection of the turret Note the location of the following parts 1 Serial line S connector 2 Image perception optics 3 Light intensity detector optics 4 68HC11 general purpose processor board 5 Vision specific piggy back 4 20 Image perception On the upper board there are two sensors situated behind the two optics 2 and 3 as described in figure 1 The linear image sensor and a global light intensity detector The image sensor is an array of 64x1 cells giving a linear image of 64 pixels with 256 grey levels each The 64 pixels have been numbered from 0 to 63 starting from the left of the field of view The view angle is of about 36 degrees as shown in figure 2 ud Figure 2 View angle of the linear camera Pixel number 0 is on the left of the field of view pixel number 63 is on the right The optics is designed to bring into focus an object situated at a distance spanning from 5 to 50 cm in front of the robot Appendix B illustrates some examples of image acquisition with a pattern placed at several distances A second sensor point 3 of figure 1 detect the light intensity and automatically adapts the basic scanning speed same functionality as an iris of the linear image sensor in order to use its full r2. T63OIDE eea n oi ded EE ex S 6 Image characteristics reading 0 000 5 8 Other characteristics of the environment 8 JD rret SEEUD sc owed eee eles ene tat dees ERES 9 Referents casados een vaca tate adc sue AUR Rae dawns 9 Appendix A Communication protocol to control the K213 VISIO DUEITOE 22e ex ERR ERE RM E ES 10 Appendix B Image examples 00000007 15 1 INTRODUCTION Odi The hardware of Khepera is based on a modular concept The K213 vision turret can be plugged on the top of the Khepera robot to extend its functionalities to linear grey level vision Due to the configuration and the geometric shape of this turret no other tur ret can be plugged on the top of this one This kind of turret is called a top turret The K213 vision turret is controlled by a local Motorola 68HC11 processor A local network makes the communication with the main processor possible All function nalities can be managed by a local protocol supported by the standard control protocol available on the basic configuration of Khepera This turret can be used only on a Khepera robot with a BIOS and protocol version greater or equal to 4 0 1 1 How to Use this Manual This manual is organised into six chapters and an appendix To learn how to make the best use of your K213 vision turret you are urged to read all of chapters 2 through 5 You need to read the chapter 6 if you use the software LabVIEW Th
3. real time Click on the stop icon to stop the program The instrument Get_16pix_subimage has the same functionality as the instru ment Get_8pix_subimage but ask for 16 successive pixels instead of 8 6 3 Image characteristics reading In addition to some simple format changes and pixel extraction the local 68HC11 processor of the K213 vision module is programmed to make some very simple preproc essing of the linear image Two very simple instruments are presented here to get the number of the pixel with maximal figure 8 and minimal intensity The analysis of the image is made at the level of the K213 vision turret and only the final result is transmit ted to this instrument through the Khepera main processor Get_pixel_mau pixel with maximal value Port noon I ul I yo Mot bor og g I rd I idl I b ror g I 1 20 20 40 50 ez Choose the port on which the robot is connected Figure 8 This instrument access to a preprocessing operation made by the local proces sor the computation of the pixel with maximal intensity To test the Get pixel max instrument please run it in the recurrent mode double arrow in running mode and move a lamp in front of the robot The maximum pixel will move with the lamp and indicates the direction of the light source The Get pixel min instrument is very similar but gives the number of the pixel having the minimum inten
4. to 4 bits pixels instead of the 8 bit pixels used by Get lin image This make a faster image acquisition possible still having all 64 pixels Get 2x subscan and Get 4x subscan are also two instruments very similar to the previous two Also in this case the resolution of the image is reduced in order to get a faster transmission In Get_2x_subscan the pixel resolution of the image is reduced and only one pixel out of two is sent and displayed In Get 4x subscan only a pixel out of four is sent and displayed The instrument Get 8pix subimage presented in figure 7 uses the possibility to ask for 8 successive pixels sub image of the linear image starting from start pixel A slider in the upper right corner is used to define the start point of the sub image bet 8piu subimage start_pixel 0 56 Port Choose the port on HODEN which the robot is connected i I I I I 1 i 0 10 20 420 40 5056 xizual arrau 230 200 I quen visual cluster 253 200 100 Figure 7 Instrument for the acquisition of 8 successive pixels in the image Also in this case to test the instrument please select the serial port on which the Khepera is connected To test this module put a large and contrasted image in front of the robot at a distance of 10 cm To read the image from the robot click on the double arrow to enter the recurrent running Move the start_pixel slider and observe the result on the panel in
5. _kheoera___ aui K213 VISION TURRET USER MANUAL Version 1 2 K Team S A Lausanne 16 March 1999 Documentation author K Team Ch de Vuasset CP111 1028 Pr verenges Switzerland info k team com http www k team com Trademark Acknowledgements IBM PC International Business Machines Corp Macintosh Apple Corp SUN Sparc Station SUN Microsystems Corp LabVIEW National Instruments Corp Khepera K Team NOTICE The contents of this manual are subject to change without notice All efforts have been made to ensure the accuracy of the content of this manual How ever should any error be detected please inform K Team Theabove notwithstanding K Team can assume no responsibility for any error in this manual TABLE OF CONTENT Introduction iive RRESEREa AU E TAULRE RR REG WE 1 How to Use this Manual sese 1 Safety Precautions 2 qu ores RR eaa ad eR ER ERO A IU os 1 Unpacking and Inspection 0 0 0 0 e eee eee eee 2 The vision TSL213 t rret e ose ed oci OR Pet ERRAT ER cd 2 Veri dus ex eed see rera er ee dhcebgR Ede E 2 Image perception 2 24 4 lees ie e r9 RR 2 Software support diskettes 0 2008 3 Connections s eeu oebsesQuheRR wd a a E ERE E RE 3 ASSSmbIg 1o a tervesen She sees aber NE hee sed 4 Disqssemblilig n uae eb EE ERI EC EESEXEY LPS 4 Using LabVIEW s asque 4r EERR ER REN INR ER RES 5 Hardware and software setup 000 eee eee 5 IitiaBe
6. ange of sensibility in a large extent of light conditions In very bright environments the sensor will be scanned very fast to avoid a saturation of the image sensor In very dark environments the sensor will be scanned at a lower fre quency because of the time necessary to collect a sufficient quantity of light This basic scanning frequency is the maximum scanning frequency that you can reach It is useless to try to get a higher speed in asking the image often you will simply get several times the same image You can have an idea of this basic scanning frequency observing the RED LED on the processor board Every time that the linear image sensor is scanned this LED is switched on and off The basic scanning process described above is made automatically by a specific hardware The 68HC11 processor is informed about every scan and can read the image generated by the scanning converting the analog signal generated by the image sensor into grey level values The processor cannot influence the scanning speed but can avoid to read the image This can be interesting when the robot is in bright environments In this kind of situation the scanning frequency is very high and the processor would be overloaded if it had to convert each image For this reason you can specify a maximum reading speed If the scanning speed is bigger that this reading speed the processor will simply avoid to read some images You can have an idea of this reading frequency ob
7. at of the command Q start_pixel Format of the response q pixel start 0 pixel start 1 pixel start 7 Effect Returns the 8 bit grey level values of 8 pixels starting from pixel number start pixel If some pixels requested are outside the image if start_pixel 61 for instance 5 requested pixels are outside the image the returned value for these pixels will be null Pixels are numbered from left to right following figure 2 R Read 16 pixels sub image Format of the command R start pixel Format of the response r pixel start 0 pixel start 1 pixel start 15 Effect Returns the 8 bit grey level values of 16 pixels starting from pixel number start pixel If some pixels requested are outside the image if start_pixel 61 for instance 13 requested pixels are outside the image the returned value for these pixels will be null Pixels are numbered from left to right following figure 2 S Read 2 times sub scanned image Format of the command S Format of the response s pixel0 pixel2 pixel4 pixel62 Effect Returns the 8 bit grey level values of only 1 out of 2 pixels For this reason the transmission is composed by 32 data bytes 14 T Read 4 times sub scanned image Format of the command T Format of the response t pixel0 pixel4 pixel8 pixel60 Effect Returns the 8 bit grey level values of only 1 out of 4 pixels For this reason the transmission is composed by 16 data bytes U Set reading peri
8. ble the turret with the basic configuration in two steps First place the module on the extension connector checking that all pins are seated correctly Second apply force to insert the turret into the extension connec tor f you want to connect the robot to your workstation use the serial connec tor of the topmost turret Operate as normal 5 2 Disassembling This is the most difficult operation for people that are not accustomed working with this type of hardware First switch OFF the robot or disconnect the power supply Separate the turret from the rest of the robot To perform this without dam age to the connections it must be removed carefully such that all pins are disconnected simultaneously One way to do this is to insert a large plastic screwdriver between adjacent modules and gently ease the boards apart being careful not to push on delicate components First open one side a bit then the other alternating sides until the module is free I8 TTT TU TTT TTT z EE A Ti a Y ip S xm VHC Hi S HOR Figure 3 How to disassemble an additional turret TUT 6 USING LABVIEW Oi The goal of this chapter is to familiarise you with the LabVIEW modules used to control the K213 vision turret To this end all steps to perform turret manipulations are presented 6 1 Hardware and software setup Set your environ
9. e appendix can be referred to as necessary Chapter 1 gives you a general introduction Chapter 2 describes some important warnings Chapter 3 explains the contents of the package Chapter 4 explains the functionality of the K213 vision turret Chapter 5 explains how to connect the K213 vision turret to the robot and to the host computer Chapter 6 is addressed to users of LabVIEW It shows some virtual instruments to control the K213 vision turret functionality AppendixA details the commands of the communication protocol Appendix B illustrates some examples of image acquisition 2 SAFETY PRECAUTIONS Oi Don t plug or unplug any connector or turret when the robot is powered by batter ies or external power supply All connections and turret insertions must be made when the robot and the interface are switched OFF Otherwise damages can occur Switch OFF the robot if you will not use it for more than a day Please disconnect the power supply removing it from the wall socket If you have any question or problem concerning this turret please contact your Khepera dealer 3 UNPACKING AND INSPECTION Oi Please check that you have a complete package You should find Documentation The K213 vision turret Disks with the software modules for LabVIEW on SUNG Macintosh and PC Please note that LabVIEW itself is NOT included in the package 4 THE K213 VISION TURRET O 4 1 Overview Top view Side view
10. e level of the resolution and the format of informa tions The first instrument we will look at is used to get the complete linear image at full resolution Be sure that the serial link has been correctly installed then open the Get_lin_image instrument present on the diskette Now your screen displays the fol lowing panel Get_lin_image Choose the port on which the robot is connected visual array z251 l l I l l I l l I l l I I l j4q 0 2 10 15 20 25 30 35 40 45 30 35 60 65 wisual_cluster autoscale 2980 200 100 Figure 6 The Get_lin_image allow to read the 64 pixels image Now select again the serial port on which the Khepera is connected To test this module put a large and contrasted image in front of the robot at a distance of 10 20 cm To read the image from the robot just click once on the run arrow Move the image and click again If you are getting bored with clicking on the arrow try one click on the dou ble arrow in running mode By this way you enter the recurrent running Move the image in front of the vision system and observe the result on the panel in real time Switch ON and OFF the autoscale function top right of the visual cluster scope to observe the effect on the display Click on the stop icon to halt the program The Get lin image 4bit instrument is very similar to the Get lin image The only difference is that in Get lin image 4bit the bit pixel resolution is reduced
11. iaturisation a tool for investigation in control algorithms ISER3 Kyoto Japan 1993 National98 National Instruments LabVIEW manuals 1998 K Team98 Khepera User Manual 5 0 K Team S A manuals Lausanne 1998 10 APPENDIX A COMMUNICATION PROTOCOL TO CONTROL THE K213 VISION TURRET Odi This communication protocol allows complete control of the functionnalities of the K213 vision turret through a RS232 serial line and the robot main processor The connec tion configuration needed is presented in section 5 2 of the Khepera USER MANUAL The setup of the serial line of your host computer must correspond to the one set on the robot with the jumpers running modes 1 to 3 The protocol used to control the K213 vision turret from the robot should not be confused with the protocol used to control the robot from a host computer We call the robot control protocol main protocol and the K213 vision turret control protocol tur ret protocol The T command of the main protocol transmits a command of the turret protocol to the additional turret with the given identification number see appendix A of the Khep era USER MANUAL The identification number of the K213 vision turret is 2 The turret protocol is constituted by commands and responses with an header in ASCII codes like for the main protocol The string of the turret protocol must be inserted in the command field of the T order of the main protocol see ap
12. ment as explained in section 5 2 of the Khepera User Manual The jumpers must be set as showed in figure 4 to obtain the running mode 2 Top view Figure 4 Settings of the jumpers to use LabVIEW Then assemble the K213 vision turret as described in Connections on page 4 of this manual and finally connect the robot to the computer as described in section 5 2 of the Khepera user manual To enable the exchange of information between your computer and the robot you have to set up the serial link Be sure that the connection cable is connected at both ends that the robot is powered then start LabVIEW and open the Set up instrument present in your diskette The following panel appears Set up the serial link with the miniature robot Ehepera baudr ate Port Taxon modem Choose the port an which the robot is connected Figure 5 Set up panel for serial link initialisation Now select the serial port on which the robot is connected This selection must be made for every module that you will use Then click once on the run arrow at the top left of the window A stop icon appears for a few seconds after what the front panel returns to its initial state That s all The serial link with Khepera is set to 19200 baud It will remain so until you put your computer off 6 2 Image reading There are several possibilities to get images from the K213 vision turret These possibilities differ essentially at th
13. mmand T turret_ID command turret protocol Format of the response t response turret protocolq Effect Send a command and return the response of the additional turret with turret ID The turret ID of the K213 vision turret is 2 The turret protocol takes the same form as a standard main protocol Every command of the turret protocol includes an identification capital letter followed if neces sary by numerical parameters separated by commas The response takes the same format starting with the same letter but in lower case followed if necessary by numerical parameters separated by commas The com mand and response formats are specific for every turret and are described in the turret protocol List of available commands of the turret protocol for the K213 vision turret B Read software version Format of the command B Format of the response b version of software revision of software Effect Read the version and revision of the K213 vision turret software running on the local 68HC11 processor 12 N Read image Format of the command N Format of the response n pixell pixel2 pixel3 pixel63 pixel64 Effect Read the 64 grey level values corresponding to the 64 pixels of the image The grey level of every pixel is coded on 8 bits For this reason the trans mission is composed by 64 data bytes The transmission of a full image between the turret and the robot takes about 6 milliseconds L Read the ligh
14. od Format of the command U period ID Format of the response u Effect Sets the minimum image reading period This period corresponds to the time that the local 68HC11 processor wait between two consecutive read ing of the image Inbetween the image is not updated and all image requests will access to the same datas The possible period ID with the corresponding scanning period are 0 200 ms default 1 50 ms 2 100 ms 3 150 ms 4 250 ms 5 500 ms 6 lsecond 7 5 seconds 15 APPENDIX B IMAGE EXAMPLES Odi Figure 10 illustates some linear images grey levels versus pixel position corre sponding to a pattern reproduced on the left placed at several distances This pattern or the copy in the next page is at 1 1 scale and can be used to test your K213 vision turret Figure 10 Images acquisitions with the left pattern placed at several distances 16
15. pendix A of the Khepera USER MANUAL A command of the turret protocol is constituted by a capital letter followed if necessary by 8 bit 0 to 255 numerical parameters separated by a comma The response is transmitted in the response field of the command T of the main protocol The response is constituted by the same letter of the command but in lower case fol lowed if necessary by 8 bit numerical parameters separated by a comma To better understand this protocol we propose a very simple test as following Set the jumpers of the robot for running mode number 1 Plug in the K213 vision turret following the instructions of section Con nections on page 4 Set the connection configuration presented in section 5 2 of the Khepera User Manual e Start a terminal emulator on your host computer for instance VT100 with the serial line set to 9600 Baud 8 bit data 1 start bit 2 stop bits no parity Type the text T 2 B followed by a carriage return or a line feed The robot must respond with t 2 b followed by an indication of the version and revision of the software running on the K213 vision turret and termi nated by a line feed Try other commands 11 Command of the main protocol for the control of an additional turret See also Appendix A of the Khepera User Manual indicates CR carriage return or LF line feed indicates CR and LF T Send a message to an additional turret Format of the co
16. serving the GREEN LED on the processor board Every time that the image is readed this LED is switched on and off The default maximum reading speed is 0 2 seconds This means that the maximum image rate that you can get is 5 Hz The fact to ask often the image data to the processor will not give you more information you will get several times the same image If you want to change this reading speed you can using the control command described in Appendix A 4 3 Software support diskettes Three 3 5 diskettes contain all the modules for the control of the K213 vision turret from LabVIEW on PC Macintosh and SUN workstations see also Using LabVIEW on page 6 5 CONNECTIONS Oi Assembling and disassembling additional turrets is a delicate operation Try to avoid it as much as possible and perform it carefully Please follow the following instructions to avoid damage to your modules K Team can assume no responsibil ity for any damage caused by improper manipulation 5 1 Assembling Assembling is the easier operation but it is also necessary to perform it carefully First of all choose the parameters of the module on to which you plan to plug the new turret the running mode that you will use on the basic Khep era configuration for instance and set the jumpers if necessary When the turrets are assembled it is impossible to access to the modules that are inside the robot without disassembling it Assem
17. sity The same test as above can be made replacing the light source with a black line on a white surface 6 4 Other characteristics of the environment As described in section Overview on page 2 the turret is provided with a light intensity detector used to adjust the image sensor sensibility This information about the general light intensity is available with the Get_rlight_intensity as described in figure 9 To test this functionality please run the instrument in the recurrent mode and observe the indicator when you direct the vision system to the light or to a dark place bet rlight intensity Tight intenzitu Choose the port on which the robot is connected Figure 9 This instrument indicates the light intensity in the field of view of the K213 vision turret 6 5 Turret set up The 68HC11 of the K213 vision turret manages on one side the image reading and on the other side the communication network To have a control on the time spent by the processor on the image reading activity it is possible to control the maximum refresh period of the image This time gives the interval between one image reading and the next Between two image reading the image is not updated and for every request the K213 vision turret will send the same image The image readind period is set using the Set_scan_speed instrument 7 REFERENCES Odi Mondada93b Mondada F Franzi E and Ienne P Mobile robot min
18. t intensity Format of the command Format of the response Lintensity value MSB intensity value LSB Effect Read the light intensity value of the field of view of the vision module The intensity 16 bits value can be computed as follow intensity value MSB 256 4intensity value LSB M Read low resolution image 4bit pixel Format of the command M Format of the response m pixell A4bits msb pixel2 A4bits lsb pixel3 4bits msb pixel4 4bits_Isb pixel63 4bits_msb pixel64 4bits_Isb Effect Read a low resolution version of the 64 grey level values corresponding to the 64 pixels of the image with the grey level of each pixel coded on 4 bit For this reason the transmission is composed by only 32 data bytes and on each byte transmitted two pixels are coded The first pixel is coded on the most significant 4 bit of the byte bit 4 to 7 the second in the lower significant 4 bit of the byte bit O to 3 O Read pixel number with maximal intensity Format of the command O Format of the response O pix max Effect Gives the number of the pixel having the maximal intensity pixels are numbered from left to right following figure 2 13 P Read pixel number with minimal intensity Format of the command P Format of the response p pix min Effect Gives the number of the pixel having the minimal intensity pixels are numbered from left to right following figure 2 Q Read 8 pixels sub image Form
Download Pdf Manuals
Related Search