基于相平面的车辆AFS与DYC可拓协调控制

Extension coordinated control of AFS and DYC for vehicles based on phase plane

为了提高汽车的操纵稳定性,弥补主动前轮转向(AFS)在轮胎侧向力饱和的情况下对车辆稳定性控制的不足,引入直接横摆力矩控制(DYC),设计了基于相平面的可拓协调控制系统,分为上、下两层。上层为AFS和DYC的功能协调层,以轮胎侧偏特性线性极限和β相图稳定域边界作为依据来划分汽车行驶状态,对应于可拓集合中的经典域、可拓域和非域,运用可拓学理论求解关联度函数,并确定控制器间的协调权重;下层为主动前轮转向控制器和直接横摆力矩控制器,均采用粒子群算法优化PID控制参数。利用Simulink与CarSim软件搭建联合仿真试验平台,选用低附单移线工况和低附阶跃转向工况进行仿真验证。结果表明,本文所设计的可拓协调控制策略能有效弥补单一主动前轮转向控制的不足,改善车辆对参考轨迹的跟踪效果,并能降低质心侧偏角,保证了车辆的行驶稳定性。

In order to improve the handling stability of vehicles and make up for the weakness of active front-wheel steering(AFS)for vehicle stability control due to the saturation of tire lateral force,direct yaw-moment control(DYC)is introduced and a two-layer extension coordinated control system based on phase plane is designed.The upper layer coordinates the functions of AFS and DYC.According to the linear limit of tire lateral characteristics and the stability domain boundary ofβphase diagram,the driving state of vehicles is divided into classical domain,extension domain and non-domain in extension set.Extenics theory is used to solve the correlation function and determine the output weight of each controller.The lower layer includes an AFS controller and a DYC controller.PID control parameters of both controllers are optimized by particle swarm optimization algorithm.Simulink and CarSim softwares are used to build a co-simulation platform.Two driving conditions(low adhesion and single lane-change,low adhesion and step input)are selected for simulation verification.The results show that the proposed extension coordinated control strategy can effectively compensate for the deficiency of AFS control,improve the tracking of reference trajectories,reduce the sideslip angle and ensure the driving stability of vehicles.