1. Princeton University Prospect Eleven Nov. 17, 2005 Control Systems Speed control module: –Receives desired speed from Speed Decision –Decides how to modulate throttle and brake Requirements –Gracefully reach and maintain desired speed –Smooth acceleration and braking To minimize skidding on loose sand wet grass –Strict adherence to speed limit Minimize overshoot –Deal with integrator windup

2. Princeton University Prospect Eleven Nov. 17, 2005 Speed Control -- Implementation Proportional Integral Control –Output = K P e v + ∫K I e v dt + K D (de v ∕dt) –Where e velocity = V desired – V current K P term deals with the bulk of error K I integrates up error to eliminate steady state error K D reduces overshoot and ringing by slowing response Speed Control Desired Speed Current Speed Latest Speeds Percent Throttle Percent Brake Tension

3. Princeton University Prospect Eleven Nov. 17, 2005 Speed Control -- Tuning The selection of constants dependent on dynamics of car –Response of motor to percent throttle –Dynamics of braking –Car is naturally dampened Air resistance Drivetrain friction Step response of car at various regimes studied Actual tuning was done through Nichols-Zieger closed- loop tuning at different regimes. Graphical debug GUI made tuning very easy.