Heard About AJAX Remote Controlled Lego Robot?

Filed in archive AJAX on July 24, 2006

Till now you have heard about AJAX being used for websites but have you ever heard about it being used for controlling a real physical lego robot in real time.

Its setup is quite simple

• A gumstix connex computer running Linux and a webserver with CGI (Common Gateway Interface).
• Some low level c code to do input mixing and giving control outputs to the Lego motors.
• A static HTML page as an AJAX control panel.
• A compact flash 802.11b wireless card.

Anybody who has an AJAX enabled browser would be able to control the robot by loading the static page hosted on the robot's web server and by using the control panel to control it in real time.

Given below are the steps to control the control panel:

1. At the center, radius = 0, motors stops
2. Increase distance to center, r > 0, motor(s) moves
3. 0 < atan2(y,x) < PI/2, go forward
4. -PI/2 < atan2(y,x) <0 , go backwards

There is also some mixing based on the angle atan2(y,x). For example, moving the mouse cursor to atan2(y,x) = 0, r=1, will yield a full forward on the left tracks and full backwards on the right track with a continues mixing based on the following formula with adjustments (+/-) depending on quadrant.

double f(double x) { return cos(2*(x-PI/2)); }

Thnx Waelchatila