Hello! Well I am in second year Engineering Physics and we're building a robot this summer. We have four students in my team including myself. We're to build a robot that follows a loop of black tape on a track, and race with other robots. I have a few questions: 1. We decided to use two motors to drive the two rear wheels, and use a servo motor with PID control to steer the front two wheels. We're wondering if it's better to use two differentials for the two rear wheels. 2. What kind of shock absorbing system should we use? The robot will probably weight at most 15 pounds. And it will have to jump off of a ramp which is probably 4-6 inches high. I'm thinking of using springs, but I haven't come up with a design yet. It would be great if you could provide a picture. Thanks!