Fuzzy Longitudinal Controller Design and Experimentation for Adaptive Cruise Control and Stop&Go

This paper presents a fuzzy longitudinal control system with car-following speed ranging from 0 to 120 km/h. This controller achieves the main functions of both adaptive cruise control (ACC) and Stop & Go control. For constructing the vehicular longitudinal control system, we use vacuum boosters to control the throttle and the braking pedal, thus circumventing the technical difficulties of using engine management system and anti-brake system. A fuzzy controller is synthesized by inputting the difference of the actual relative distance and the safe distance obtained from the preceding vehicle, and the relative speed, and then outputting the pulse-width-modulation (PWM) signal to control the output forces of the vacuum boosters. With the use of the high-level controller from dSPACE, the fuzzy control law is easily and rapidly implemented using Simulink for the experimental car, and the controller’s parameters can be changed and updated by analyzing the collected data from the relative distance from the lidar, the speed of the host vehicle, the opening of the throttle and the position of the braking pedal. Modified by a commercial SUV, the experimental car is equipped with a lidar on the bumper, a speed sensor mounted at the shaft of a wheel, and two sensors for measuring the opening of the throttle and the position of the braking pedal. For the sake of safe testing, experimental results are conducted by virtually simulating the various possible car-following conditions for the ACC and Stop & Go controllers, thereby obtaining virtually relative distance and speed to tune the controller’s parameters and make sure the safety of the controller. Afterwards, the realistic car following experiments are then conducted to confirm that the proposed fuzzy controller is capable of achieving the requirements of comfort and safety and giving a satisfactory performance at high and low speed conditions..