16x62 Robot User`s Manual Introduction
Contents
1. up a little window in which the sonar values are drawn The method DrawSonars does the job and takes as an argument the RobotController where SonarConsole can find the stateArray where the sonar values are stored So this code opens up a sonar drawing window turns on the sonars of the robot then goes into a loop updating the stateArray each time printing out the front sonar s value to the Messages window and redrawing the sonars In the meantime it checks to see if the bumper is in If it is the whole program exits to show you how to use exit It also waits half a second between subsequent cycles Connect up the portable to a robot and try this program out Notice that in the Messages box you can see the front sonar s value printing out Play with the sonars on the robot hear them clicking and try stopping the program with the bumper Notice that the sonars stop too That s because we were careful to turn them off in the program right before the System exit 0 call Note if you couldn t have stopped the program with the bumper the only way you could have terminated it would have been with Ctrl Alt Del It s a pain we know The deal is this is truly a single threaded machine for simplicity and to ensure that your robot control software gets plenty of processing cycles So once you re running an infinite loop none of the other buttons on your program work any longer Now let s look at the MouseClick code f2. 16x62 Robot User s Manual Introduction Welcome to 16x62 Robot Programming Laboratory This manual is your guide to the Nomad Scout robots that you will be programming this semester This guide details the robot hardware operation communication and user software Robot Hardware Description Mechanical System The Nomad Scout mobile base is a differential direct drive non holonomic system can t go sideways with zero gyro radius can turn on a dime A dedicated 68332 board performs all the hard work with help from an hc6811 that controls the 16 sonars The base has a maximum translational speed of about 30 inches per second approximately and a maximum rotational speed of 50 degrees per second Electrical System Each robot uses two large and heavy sealed 12 volt batteries We estimate the maximum running time of a robot with fully charged batteries to be about 12 hours This is based on the fact that the processors use a total of only 500 milliamps But the batteries are sealed lead acid batteries If they are fully depleted deep cycled they won t last through this semester Avoid using a robot for more than six hours straight The batteries can last hundreds of shallow cycles Do not remove the batteries from the scouts and or swap batteries between scouts Ever The scout has a very nice feature a built in charging unit To charge the scout simply plug it into the wall There is one huge catch THE ROBOT MUST BE ON
3. FOR THE CHARGING CIRCUIT TO WORK This means no matter how long you leave it plugged in if the scout is off charging will not happen So at night when you tuck the scouts in leave them plugged in and on Like R2D2 the scouts communicate with you by beeping When you plug them in and they re on they will emit two short beeps Then if the batteries are half full you ll hear two long beeps If the batteries are totally full you Il hear 4 short beeps If you hear a continuous beep during operation that s the low battery warning beep Plug the robot in don t turn it off immediately Of course the Toshiba notebook housed on top of the robot runs off its own battery or ac adaptor The Toshiba battery only lasts about 3 hours In a cruel twist of fate the Toshiba batteries are Lithium which means deep cycling them is good One really nice feature of the Toshiba s is if you close the lid the monitor turns off after a high pitched squeal but your program keeps running To preserve your notebook battery close the lid whenever you don t need to see what s on the screen This makes a huge difference to the battery s discharge rate Also whenever you and your robot aren t moving plug that portable into the wall There are extension cords for this purpose awaiting you in the Lab Important points to remember ALWAYS leave the portables in the Lab overnight they really really don t want to go home with you Th
4. about put in a 255 Make sure the whole array is 16 long buffer it with zeroes If you want just the back sonar to fire here s what you do int sonars new int 16 10 sonars 15 0 configureSonars 4 sonars Note that the sonars numbers are 0 through 15 0 is straight ahead 15 is 1 o clock Yes I know in State_Array they re index numbers 1 through 16 But the sonars actual numbers for purposes of ordering them in ConfigureSonars are 0 15 Furthermore note that if you call turnSonarsOn after calling this method then your configuration will be clobbered ConfigureSonars actually causes the sonars to be on when used right so never call turnSonarsOn afterwards int setTimeout int timeout This command allows you to reset the amount of time after which a velocity command is thrown away and the robot limps it if received no further communication The default is two seconds Remember the best way to override a velocity command is to simply send another one The parameter is an integer number of seconds We believe if you set timeout to be 0 then a command never times out In terms of safety that s a bad idea 11
5. arConsole java Simple code that allows you to draw a little graphic of the sonar hits on the screen Okay Now start up SampleBot in the development environment by double clicking on SampleBot vep The project window at left shows the main ingredients Applet is trivial RobotController is what we supply for talking to the robot SonarConsole is what we supply for drawing sonars and Robot is where you put your code Now double click on Robot so we can show you key features of your coding environment Robot Form Designer shows you the layout of our sample Robot Java window We ve put two buttons on this window and by looking at the code we ve written for these two buttons you ll learn just about everything you need to know to start hacking robotics Double click on the Form Designer anywhere to look at the source Java code As you can see this is just a subclass of Frame The extra global variable we added is a RobotController RC In the constructor after the auto generated code you will see that we make this window visible we instantiate RC to be a RobotController instance and we open the serial port of the portable so it can gab with the robot Now choose the button2 s MouseClick event code This is the code that runs when you hit the button Run Sonar Loop The interesting thing here is first of all that we create an instance of the one other class we re giving you SonarConsole This instance literally pops
6. ars off when they get annoying int GS Get the stateArray all updated You do NOT need to call this function if you call any other robot command function since stateArray is updated when any robot communication is performed int setVel int leftVel int rightVel Your bread and butter Set the velocities of the left and right wheels in tenths of inches per second int killMotors This command is a much more graceful way of causing the robot to stop than setvel 0 0 because the latter command causes the motors to freeze while killMotors simply cuts off power and allows the robot to coast to a halt int setAccel int leftAccel int rightAccel Configure the acceleration of the left and right wheels of the robot make it the same please in tenths of inches per second per second Default is about 100 int configureSonars int firingRate int sonarOrder You can use this command to specify how long the robot should wait between firing sonars and which sonars to fire and in which order The firing rate is a number specifying how many 4 millisecond intervals the robot should wait between firings Set it to a number between 2 and 254 Hint use 4 or more The sonarOrder is an array containing exactly sixteen integers The order of the numbers indicates the firing order If you want to fire only the front three sonars sonarOrder would be 0 1 15 255 0 0 0 0 0 0 0 0 0 0 0 0 As you can now guess after you put in all the sonars you care
7. at The development environment that you create will include a source class called RobotController This is the code for the low level interface that allows the portable to talk to the robot This JAVA code actually calls a C dynamic link library cscout lib and cscout dll where the goodies are really implemented You can look at all the C side source code if you care in the Robocode site off of Illah s website Please remember to back up your work Every laptop has a disk drive in its belly and you have received a team disk for this class Java code doesn t take up much room thre is no excuse for you to lose your code Also there is no guarantee that from one work session to the next you ll be able to use the same notebook So you probably want your code on disk anyway From You to the Robot the simple version The software section below will tell you how to create your robot development environment in Visual Cafe Once that is done your most important command to the robot is the function setvel leftwheel rightwheel This function like the several other robot commands sends a stream of characters via the serial port to the robot This stream of characters encodes your intended rotational velocities for the two wheels of the robot in tenths of inches per second For instance setvel 200 200 would mean move forward at 20 inches per second The range of velocity is an INTEGER between 300 and 300 a negative velocity i
8. e Sonar System The round gold coins are the robots only range sensors sonars These transducers provide surprisingly accurate range information from 6 inches to 255 inches Each Polaroid Tranducer has a beam width of about 25 degrees although there may be variation in this beam width or half cone from sonar to sonar A single sonar unit works as follows The transducer emits a series of 16 pulses at a frequency of 49 4 KHZ The echo receiver circuitry is disabled or blanked for about 1 millisecond during and slightly beyond this emission phase so that the initial pulses are not detected as echoes This blanking has a serious effect at close ranges known as double echo If the robot is closer than about 3 inches to an object then the return echo from that object could occur while the echo receiver circuitry is still blanking Therefore the object might appear to be farther away than it actually is Also a sonar signal will bounce away instead of returning if it hits a smooth object at a shallow angle of attack in effect it can glance off coherently This will also result in the strike distance being larger than it should be 1 0 15 22 5 deg 2 14 6 10 transducer The Bumper System The Scout s bumpers are not great so consider yourself warned There are six discrete pressure sensitive strips arranged as in the following diagram The value of the bumper state communicates which bumpers depressed The lowest order bit
9. eam directory make a directory in C 16x62 for your team then copy the directory C 16x62 SampleBot into your directory WARNING Copy these files don t move them To select multiple files hold down the Ctrl key To copy instead of moving just use Ctrl C and Ctrl V rather than drag and drop If you move the files and wreak havoc we will make you brand new a fresh 9 volt battery Now we are going to walk you through the code in SampleBot and lead you through a tour of how to use this stuff To do this tour properly you need a robot and a portable duh WARNING Before you do this tour it would do you well to go through our Java Primer and set up the brainless calculator We will assume that you have already done that when you do the following Let the Tour Begin Let s go to the SampleBot directory in your team s directory Look at the files The ones you care about and what they are Appleti java This is the java code for the outermost shell that we use We always wrap things in an applet so that someday you can put your code on the web Cscout dll Cscout lib This is the C code that we link to your program to enable Java to talk to the robots via serial link Robot java This is the sample code that we have written to control the robot When you write your own Robot java you will have the robot doing your own things SampleBot vep This is the project file that you double click on to get the project open Son
10. encoder is off even a little the entire x y position will become more and more inaccurate as the robot moves You ll be accessing these elements often and we wanted you not to have to remember numbers like 17 18 and 19 So we ve made static constants for you XPOS YPOS and THETA among others So for instance to check your robot s angle if your RobotController instance is named RC you d type RC stateArray RC THETA Wheel Velocities 20 and 21 These are the current translational velocities of the robot s wheels You probably will never look at these although it might be fun to look at them after issuing a command to see how well the built in PID motor controller matches the actual velocities to the ones you requested Again we ve defined constants for you RVEL and LVEL Bumper Status 22 This is another really important sensor The bumper status will be zero if none of the bumpers are depressed If any bumper is depressed this will be nonzero By the way there are really 6 separate bumpers on the robot and each one can be on or off And from this one number you can figure out which are depressed and which aren t But don t you bother with that just yet User Software You will be writing Java code in Symantec Visual Cafe Version You need to create your own project directory which will include all the interface code that we have written to enable your computer robot communication To set up your own t
11. ndicates backward movement The indoor spaces are very confined thus you should not specify velocities anywhere near 300 or 300 in any case The behavior of the robot when it receives a command of the form setvei is precisely as follows in this order 1 Updates sonar and encoder values from the robot into stateArray 2 Begins executing simultaneously the specified wheel speeds 3 Continues executing this motion until the robot receives a new command of any kind or until the command times out This timeout defaults to the value 2 second However you have the power to change this default to accomplish such feats refer to the For Experts Only section of this manual which describes all available robot commands You need to use two other commands at a minimum Please note you can use only the four commands described in this section and will be able to complete all lab assignments and even win the final contest You do not need to look at the For Experts Only section to do well in this course I may be wrong The last two commands are the easiest to describe To use the sonars you Il need to turn them on Do so by issuing the turnsonarson command To turn them off when they get on your nerves use the turnSonarsoff command This is a good idea in general because it also saves battery power When your program exits it would be a good idea if it automatically send a sonarsoff command to the robot but if the robot doesn
12. or button Run Sample Program Go ahead and run this program but make sure the robot has some space in front of and behind it and unplug the portable and robot from the wall The robot s looking at the values of the front most and rear most sonars and moving away slowly from whichever is shorter Hit the bumper and the loops stops returning you to your Robot console You can see how the front and back sonar values are retrieved from stateArray Done deal Goodies There are actually quite a few goodies that we ll give you over the course of the quarter Some are edible some are good functions to do cool things like get your robot to talk to another robot not so edible So look for them For Robot Experts Only not really The following is a complete description of all robot interface functions available to send commands to the robot They all update stateArray identical to setve1 They are all methods in RobotController int serialOpen Open the serial port of the portable so it can communicate with the robot int serialClose Close the serial port of the portable Now why would you want to do this int turnSonarsOn Turns all 16 sonars on in some nice firing pattern and firing speed Use this at first NOTE this method actually just calls configureSonars with delay of 4 and a simple circular firing pattern for all the sonars Literally just a call to configureSonars int turnSonarsOff Turn all the son
13. r way to move the robot is to turn it off before pushing to ensure that the wheels are not locked Pushing the robot around is perfectly fine but if you want to show off your muscle you can even lift the robot Please don t lift the robot with the portable on top of it over long distances then cause both to come crashing down Now there is a solution to pushing the robot manually or lifting it it s called the joystick Just plug it in turn the robot on and away you go Catch when trying to use the joystick as a dead man s switch you must be pushing down on one of the buttons beside the joystick It doesn t matter which one Communication The Setup Each robot needs a portable as its brain The robot and portable talk to one another via the serial port on the left side or back side of the portable and the port labeled host on the robot This means you must plug the serial plug from the robot host port into the serial port on the portable I guarantee you that the second time you think the robot s broken you actually just forgot to plug the serial ports together the first time you forgot to turn it on On every portable our class directory is Robot User Each group should create their own folder within the Robot User folder In your group s folder you may do whatever you want Further down this manual we tell you how to set up your own Symantec Visual Cafe JAVA development environment in your folder Do th
14. represents the status of bumper 0 0 for no contact 1 for contact and so on For example the bumper state 0 means that the scout is touching nothing Checking for bumper state to be nonzero is about all you ll need to do for at least the first 50 of this course Hardware Failures If you suspect a hardware problem send email immediately to illah cs Always use common sense For instance if the wheels of the robot are clicking violently or the robot is smoking profusely stop using it to avoid further damage until we take a look at it Robot Operation Turning Robots On Each robot has a grey push power switch Simply turn the robot on using this switch You ll notice that when you turn the robot on nothing dramatic happens The sonars won t even begin echoing But the small green power LED turns on To turn on the sonars and move the robot requires software on commands from the portable That is where the fun begins If the robot s emitting a high pitch squeal as it sits rammed into a wall the motors are being overdriven Turn the robot off using the red push switch then stop your program and debug away Moving the Robot Manually You should never try to move the robot manually when the portable is sending motion commands to it Doing so will cause damage to the robot and possibly to you To push the robot around stop sending commands to the robot and wait a few seconds to ensure that the command has timed out Anothe
15. t receive this command you can turn off the sonars by physically powering down the robot By the way we are using a completely object oriented environment So there is a class called RobotController Strictly speaking the way you use the above commands is by creating an instance of RobotController and calling it something like myDumbRobot Then you tell the robot to move by typing in myDumbRobot setVel 20 20 Et cetera From the Robot to You When you issue a command to the robot the State_Array slot in your instance of RobotController is updated The following is your guide to interpreting stateArray Note that we tell you more than you need to know for this class about this state vector In particular you will probably use the sonar readings and the integrated encoder position readings but you may never use the measured velocity readings or the motor status reading Interesting idea you can use the motor velocity readings to see if you re pushing against a wall or another robot NOTE stateArray is an array of int s so you access its elements using the C based syntax stateArray index Return Value The first element of the stateArray 0 is the C side return value of the last executed command You can ignore this unless you re a cool hacker Sonar Values index 1 16 These are the 16 sonar sensor readings Each element is an integer between 5 and 255 where the integer is precisely the number of inches from the sonar
16. transducer to the object that caused an echo The sonars are arranged in a counterclockwise direction with the sensor in the twelve o clock position being index 1 element 1 of the array and the sensor at the one o clock direction of the robot being element 16 of the array Integrated Position Encoders index 17 19 These provide the robot s idea of its position based upon its encoder values 17 provides position along the x axis 18 provides position along the y axis 19 provides the angle of the robot with respect to their orientation when the robot was turned on When you turn the robot on the encoders are all set to zero That means that the robot resets its Cartesian grid to be lined up with its current orientation whatever that may be with the robot pointing straight up the X axis with Theta 0 As the robot moves the encoders show the robot s position and orientation on that grid using tenths of inches and tenths of degrees The range of values for the robot s encoded angle is from 0 to 3599 X position and Y position can have positive or negative values depending on the quadrant that the robot is in within its make believe Cartesian grid The x axis is aligned with the 0 degree orientation if you think about this a bit it makes perfect sense There s an important reason why you shouldn t blindly trust your encoders they are subject to compounding error the wheels slip asymmetrically on the carpet Once the rotational
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