eROVER Build your own web cam robot

EROVER Building Instructions:
(instructions for making the control system at the bottom of page)

How to set up your robot:
You will need the following:

RCXCC to program the rcx in NQC

web brick to provide interface between your webpage and the RCX

True Tech Webcam software to provide the streaming webcam image.

You will also need to edit some HTML for this project.

You will need a LEGO RCX. 1.0 is the best because it has a external power adapter, making your webcam run at top speed all the time. So if you do have a 1.0 RCX find a 9-12v AC adapter.

You also need the LEGO Vision Command Camera to make it more interesting for the people driving your robot.

Robot Control Page

controls example
click on em

Ok so now that you have gotten all those programs listed above you need to make them work together to form your webcam robot. First you need to put together a web page interface for your robot. You can use mine as a starter and also the API on the web brick site.

Basically you just need to copy the javascript program from the API into the top of your page and then use a button to start the function you want from the API. I used tasks for each function i wanted the robot to do. An example of one of my buttons is:
<button TYPE="button" VALUE="name" onclick="ExecuteNow(1,4)">

onclick="ExecuteNow(1,4)" tells the API to run program 1, task 4. If you wanted to say run program 5, task 2 you would use onclick="ExecuteNow(5,2)"

To make your control page just arrange some buttons and assign then each a different task#
WEBBRICK API CODE - paste in the head section of your control page
<SCRIPT language=JavaScript> // WebBrick Javascript API version 1.0 // Amnon Silverstein, Feb 2001 /// Setup variables // PUT YOUR URL HERE var WebBrickURL="http://" + myip + ":7070/"; var Attempts = 20; // Number of attempts to reach the WebBrick server var TryFor_msec = 500; // msec per wait for reply /// Global variables var DataImage = new Image(); var Timeout=0; var Sensor=0; Queue_Tasks=new Array(); Queue_Active=0; AlphaCodes="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; /////////////////////////////////// ///// WebBrick Helper Functions ///// You probably want to keep these. function GetNumber(){ return ((DataImage.width-1)+(DataImage.height-1)*256*256); } function TryReading(OnReading,OnFailure){ Timeout++; if (Timeout>Attempts){ Timeout=0; eval(OnFailure); ClearQueue(); // Cleans out the queue until the problem can be solved } else if (DataImage.complete){ Reading=GetNumber(); Timeout=0; eval(OnReading); Queue(); // Runs the next task in the queue } else window.setTimeout("TryReading("+Freeze(OnReading)+","+Freeze(OnFailure)+")",TryFor_msec); } function AlertFailure(){ // This code runs when the reading fails, by default // You can increase the number of connect attempts if you like. } function Freeze(task){ // Inverse of Eval // eval(Freeze(foo)) => foo // Converts a task into a string that can later be evaled // replace every " with \" // replace every \ with \\ quote = '"'; slash = '\\'; i=0; while (i<task.length){ if (task.charAt(i)==quote || task.charAt(i)==slash){ head=task.substring(0,i); tail=task.substring(i,task.length); task=head+slash+tail; i++; } i++; } return (quote+task+quote); } /////////////////////////////////// ///// Main WebBrick Functions ///// It is usually better to call these with the queued versions instead of directly function Execute(RCXprogram,RCXtask,OnExecuted,OnFailure){ delete DataImage; DataImage = new Image(); DataImage.src = WebBrickURL+"X"+RCXprogram+RCXtask+Math.random(); window.setTimeout("TryReading("+Freeze(OnExecuted)+","+Freeze(OnFailure)+")",1000); } ////////////////////////////////////// /////// Task Queue function Queue(task){ // Stacks up tasks on a todo list, and executes them as fast as your robot // can acknowledge them. if (!Queue_Active && task){ Queue_Active=1; eval(task) } else if (task){ Queue_Tasks[Queue_Tasks.length]=task; } else if (Queue_Tasks.length==0) Queue_Active=0; else{ next_task=Queue_Tasks[0]; Queue_Tasks.reverse(); Queue_Tasks.length--; Queue_Tasks.reverse(); eval(next_task); } } function ClearQueue(){ // Clears out all queued tasks. Queue_Tasks.length=0; Queue_Active=0; } function DontQueue(task){ // Runs the task only if not currently busy. // If your user is mashing buttons too fast, // you might want this to toss out commands until the last command finishes. if (!Queue_Active) Queue(task); } function OverrideQueue(task){ // This is for stuff that you want to run immediately, // and to override all previous commands. // Useful for Halt All, for example. ClearQueue(); eval(task); } //////////////////////////////////////////////////// //// Functions you probably want to use in your code //// These functions deal with the queue for you function ExecuteNow(RCXprogram,RCXtask){ // Simplified Execute command // Forgets what it was doing before and starts this new task. // Do not use this if you want your robot to do several things // in sequence with one button press. OverrideQueue("Execute("+RCXprogram+","+RCXtask+","+Freeze("")+","+Freeze("AlertFailure()")+")"); } function DoExecute(RCXprogram,RCXtask){ // Simplified Execute command // Puts the command in the queue, and executes it in turn. Queue("Execute("+RCXprogram+","+RCXtask+","+Freeze("")+","+Freeze("AlertFailure()")+")"); } function DoSet(RCXvar,RCXval){ // Puts the set instruction in the queue, and executes it in turn. Queue("Set("+RCXvar+","+RCXval+","+Freeze("")+","+Freeze("AlertFailure()")+")"); } function DoPoll(PollSource,PollNumber,OnReading){ task="Poll("+PollSource+","+PollNumber+","+Freeze(OnReading)+","+Freeze("AlertFailure()")+")"; Queue(task); } ////////////////////////////////////////////////////////////////////////////////////////////////////////////// //// END OF API /////// Put your own HTML code after these scripts. </SCRIPT>

VERY IMPORTANT TIP: use a small javascript program at the top of your control page like this:
<SCRIPT type="text/javascript">var myip = "put your ip address here";</SCRIPT>

...to place your IP address in all the right places through out your page without having to search through it and type it multiple times. Just put " + myip + " wherever your IP is required

(" + myip + " is already in all of the code samples i have so all you need to do is copy this the little javascript code into the HEAD section of your page and put in your own IP address)

Robot NQC Program
Next, write the program in NQC to make the RCX move when you press a button on your control page. I used 10 tasks to make my robot move. Each task does one thing such as rotate right or tilt the camera up. The tasks are numbered according to which one comes first in the program so put them in order so that the first task matches the button you assigned task 1 and so on. See the NQC tutorial that come with RCXCC for more info. Here is my nqc program for an example.

NQC CODE - erover.nqc
task main() //1 forward { SetSensor(SENSOR_1,SENSOR_TOUCH); OnFwd(OUT_A); OnFwd(OUT_C); Wait(100); Off(OUT_A); Off(OUT_C); } task backward() //2 reverse { OnRev(OUT_A); OnRev(OUT_C); Wait(100); Off(OUT_A); Off(OUT_C); } task left() //3 left { OnRev(OUT_A); OnFwd(OUT_C); Wait(60); Off(OUT_A); Off(OUT_C); } task right() //4 right { OnFwd(OUT_A); OnRev(OUT_C); Wait(60); Off(OUT_A); Off(OUT_C); } task panup() //5 up { OnRev(OUT_B); Wait(10); Off(OUT_B); } task pandown() //6 down { OnFwd(OUT_B); Wait(10); Off(OUT_B); } task forwardFast() //7 forward { SetSensor(SENSOR_1,SENSOR_TOUCH); OnFwd(OUT_A); OnFwd(OUT_C); Wait(500); Off(OUT_A); Off(OUT_C); } task backwardFast() //8 reverse { OnRev(OUT_A); OnRev(OUT_C); Wait(500); Off(OUT_A); Off(OUT_C); } task leftFast() //9 left { OnRev(OUT_A); OnFwd(OUT_C); Wait(200); Off(OUT_A); Off(OUT_C); } task rightFast() //10 right { OnFwd(OUT_A); OnRev(OUT_C); Wait(200); Off(OUT_A); Off(OUT_C); }

Web Cam
After that you will probably want to add a webcam so people can see where they are going. I copied the javascript code from my true tech webcam page and stuck it into the control page.

WEB CAM CODE - Just paste this where you want your webcam image to appear
<SCRIPT type="text/javascript">  </SCRIPT>

Making it all work
So now you are probably going to want to get your robot working. First start Web Brick and click on [OPEN SOCKET]. Copy your IP address from Web Brick into the appropriate places in your control page (once at the top of the API script and in two places in the web cam script). save changes to your page. Next start the Web Cam software. Now upload your control page to your website.

Troubleshooting
Now your robot should be working. But it probably isn't. Make sure you have your ip address entered correctly in all the appropriate places in your control webpage. Make sure you have webbrick connected also. You should also test your program in RCXCC using the direct control pannel to run your different tasks and see that they are running properly. if you need any more help feel free to contact me.

For more help see: Web Brick site and NQC tutorial that comes with RCXCC.

©2001-2004 Jesse Palmer
Please Email me before using anything from this site unless otherwise stated. If you find any broken images links or other errors, please email me about it.
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