Adaptive Cascade Optimum Braking Control Based on a Novel Mechatronic Booster

BBW (Brake-by-wire) can increase the electric and hybrid vehicles performance and safety. This paper proposes a novel mechatronic booster system, which includes APS (active power source), PFE (pedal feel emulator), ECU (electronic control unit). The system is easily disturbed when the system parameters and the outside conditions change. The system performance is weakened. The cascade control technique can be used to solve the problem. This paper develops an adaptive cascade optimum control (ACOC) algorithm based on the novel mechatronic booster system. The system is divided into main loop and servo loop, both of them are closed-loop system. The servo-loop system can eliminate the disturbance which exists in the servo loop. So the robustness of the cascade control system is improved than which of the general closed-loop control system. Different control object is respectively chosen. The control-oriented mathematical model is designed. Based on the control-oriented model, optimum control algorithm(LQR) is used to design the servo-loop controller for optimum error and rapid response. To eliminate the system uncertainty and control the hydraulic pressure accurately, adaptive control algorithm, which includes the feedforward controller and the adaptive module based on the recursive least-square algorithm with a fixed forgetting factor(λ)(abbr. RFF), is used to design the main-loop controller. The performance of the novel mechatronic booster system is evaluated by co-simulation and bench test. Experimental results prove that the system fulfills the requirements of the brake system for automotive. Compared with using PI single-loop system and cascade PI system, the adaptive cascade optimum control algorithm can improve the rapidity and robustness of system. The system performance is also enhanced.