[Hawiian Cadder]

I worked on a control scheme for a vex robot that assumes the robot is always traveling in a curve with radius R. The difference in power between the sides of the skid steer then becomes K(1/R), thus as the radius of the curve goes to infinity the difference between wheel speeds approaches 0. R had a realistic minimum in my setup (navigating a black tape maze with a light sensor) and so the algorithm worked well. For FRC it would need modification for points where R approached 0.

To achieve smooth controll I would use a PID loop where the direct control was how far side to side the robot was off course. This would control the path, planned such that the arc would cross the intended path at some fraction of the remaining distance to travel. By controlling the average of the two wheel speeds in skid steer, as wheel as the radius of the turn one could achieve any possible path. This would require closed loop motor control, as well as some method to determine where the robot actually was, as opposed to where it needed to be.