I don't know if this is what you are looking to do, but...
To quote myself from our robot design in 2002....
"The team’s very ambitious electrical team has developed sophisticated controls, wiring, and programming to navigate the machine. The navigational system compliments the robot design very well. Important symbiotic relationships continue to develop between the electrical and mechanical systems as well as between the drivers and driver feedback systems.
The electrical team of students and engineers has created a system that would enable independent control of the machine by a visually impaired driver. Code named I.D.A.N. (Intelligent Detection, Analysis and Navigation), the system allows the robot to provide audio feedback to a laptop computer.
The cornerstone of this system is a tiny magnetic sensor that will read the earth’s magnetic field. The signal it sends out will identify the direction the robot is facing. This information also establishes the robot’s location within the five zones of the playing field. An optical switch receives a signal every time the robot moves over a line of white tape bordering each zone.
The robot has been installed with optical switches on servomotors, which allow it to “scan” for the goals and correct its path automatically. The optical switches respond to the retro-reflective properties of the tape on each goal. A pressure sensor inside the robot arms will determine that the goal is secure. The Sie-H2O-Bot team looks forward to gaining extremely valuable experience with this very sophisticated system as the season progresses.
Our experimental "Blind Drive" system won us the leadership in controls award in NYC as well."
HERE IS THE ORIGINAL POST WITH MORE INFO
If you want any more info, contact me and I will try and get it.
(Oh, and BTW it was all made 100% legal to FIRST rules in 2002)