四轮转向车辆的直接横摆力矩控制研究

Research on Direct Yaw Moment Control of Four Wheel Steering Vehicle

以四轮转向汽车为研究对象,建立七自由度车辆模型、轮胎模型、理想跟踪模型;设计直接横摆力矩和四轮转向相结合的车辆稳定性控制策略。以跟踪理想的质心侧偏角和横摆角速度为控制目标,设计滑模控制器产生车辆转向所需的横摆力矩和后轮转角,按单侧制动的方法将产生的横摆力矩分配到车辆的四个车轮上,通过制动力矩的分配以及转向角的修正,使车辆转向行驶时的横摆角速度和质心侧偏角跟踪理想模型。针对七自由度模型,在Matlab/Simulink中与比例控制四轮转向进行阶跃输入和正弦输入两种工况下的时域仿真对比。仿真结果表明,基于直接横摆力矩和四轮转向相结合的的控制策略有效减小了质心侧偏角,横摆角速度对理想值有很好的跟踪,提高了车辆的操纵稳定性,同时验证了横摆力矩分配的有效性。

A four-wheel steering vehicle is taken as the research object,a seven-degrees-of-freedom vehicle model,a tire model and an ideal tracking model are established.The vehicle stability control strategy combining the direct yaw moment and the four-wheel steering is designed. By using ideal value of sideslip angle and yaw rate as goal tracked,the sliding mode controller is designed to generate the yaw moment and the rear wheel rotation angle required by the vehicle steering,and the yaw moment generated according to the unilateral braking method is distributed to the vehicle of the four wheels,the yaw rate and side-slip angle will good track the ideal model by the control of the distribution of the braking force and the correction of the steering angle. The proportional control and direct yaw moment control are compared by Matlab/Simulink under two operating conditions of the step input and the sinusoidal input of the steering wheel of the seven-degrees-of-freedom. The results of simulation show that the control strategy based on the combination of direct yaw moment and four-wheel steering effectively reduces the sideslip angle and the ideal yaw rate has good tracking of ideal value,improves the handling and stability and verifies the effectiveness of yaw moment distribution.