汽车电动助力转向(Electric power steering,EPS)系统与电子稳定程序(Electronic stability program,ESP)对保证汽车具有良好的操纵稳定性和行驶安全性起到重要作用。针对汽车纵侧向动力学存在的耦合因素,提出一种基于汽车行驶安全边界的EPS与ESP协调控制策略。建立EPS模型,通过Luenberger观测器估计回正力矩,由回正力矩信息估计路面附着系数。根据车辆动力学特性确定由质心侧偏角和横摆角速度组成的行驶安全边界,根据确定的安全边界和转向盘转矩、横摆角速度等信息,基于带精英策略的非支配排序遗传算法(Non-dominated sorting genetic algorithm,NSGA-II)优化EPS与ESP的动态协调控制因子,确保获得优化参数的全局最优解。仿真与试验结果表明,采用基于行驶安全边界的EPS与ESP协调控制策略,改善了汽车的行驶稳定性,从而验证了所提出的控制策略的有效性。
Electric power steering(EPS) system and electronic stability program(ESP) play an important role in ensuring the vehicle good handling stability and driving safety. For the coupling factors exist in the vehicles' longitudinal and lateral dynamics, a coordinated control strategy of EPS and ESP based on vehicle driving safe boundary is proposed. An EPS model is established, aligning torque is estimated by Luenberger observer, and tire-road friction coefficient is estimated from the aligning torque information. Driving safe boundary consisting of sideslip angle and yaw rate is determined by the vehicle dynamics features, according to the established safe boundary and steering wheel torque, yaw rate information etc., EPS and ESP dynamic coordinated control factors are optimized by the elitist non-dominated sorting genetic algorithm(NSGA-II), and guarantee obtaining a global optimal solution of the parameters. The simulation and experiment results validate the EPS and ESP coordinated control strategy based on driving safe boundary, can improve the driving stability of the vehicle, thus the effectiveness of the proposed control strategy is verified.