Basing a Robot on an R/C Tank

The first mobile robot I ever built used treads. It was a modified R/C tank with a small HC11-based microcontroller to control the speed of the treads. This was made though the type of speed controller typically used for R/C cars. Although this looked like a good solution at the time, it turned out to be a disaster. R/C toys are made to run very fast and tanks are no exceptions. It was almost impossible to make the robot run slowly. The closest we got was to rapidly turn the power for the motors on and off which resulted in small uncontrolled jumps. I have since realized that I was neither the first nor the last to make this mistake. I have only seen a toy tank being used for a robot successfully once and they had replaced all part of the toy except for the actual treads. Even though it looks as if a toy tank is the ideal starting point for a threaded robot, it isn't!