四轮转向干预下电动助力转向控制策略研究

四轮转向（4WS）车辆相较于前轮转向（FWS）车辆具有更高的灵活性,其后轮转向在提高车辆操稳性的同时转向阻力矩也发生变化,使得原电动助力转向系统助力策略与四轮转向车辆不匹配,对行车安全产生影响.本文以线性二自由度车辆模型为基础,对比分析了前轮转向车辆与四轮转向车辆的转向特性,提出电动助力转向修正控制策略.仿真结果表明,角阶跃工况下,有助力修正的四轮转向车辆,驾驶员操纵方向盘力矩与驾驶前轮转向车辆基本一致,既保证了四轮转向车辆低速时的操纵轻便性,也兼顾了高速时的操纵稳定性.

A Study on Control Strategy of Electric Power Steering with Interference of Four Wheel Steering

Four-wheel steering （4WS） vehicles are more flexible than front-wheel steering （FWS） vehicles. However, the steering resistance torque varies as the improvement of vehicle handling and stability with rear-wheel steering, which makes the power strategy of the original electric power steering system mismatch with 4WS vehicles and affects driving safety. Based on the 2-DOF linear bicycle model, the steering characteristics of front-wheel steering vehicles and four-wheel steering vehicles are compared and analyzed, and the modified control strategy of electric power steering is proposed. The simulation results show that the steering wheel torque of the 4WS vehicle with power correction is basically the same as that of the FWS vehicle under the condition of angle step, which not only ensures the handling portability of the four-wheel steering vehicle at low speed but also takes into account the handling stability at high speed.