Abstract: A longitudinal control system based on throttle and brake control is designed. A novel fuzzy-step algorithm is developed to eliminate the vibration of the brake pedal when braking control activates. Experiments show that the output of the controller can drive the brake pedal to move stepwise and smoothly. Also, a switching strategy between throttle control and brake control is improved, and tests show that the switching is successful. As a result, the control system has smooth behaviors for velocity tracking.