线控主动四轮转向汽车控制策略研究

目的 针对线控四轮转向汽车横向稳定性不足及控制鲁棒性差等问题,提出一种主动转向反馈控制策略。方法 使用Simulink搭建线控转向系统转向执行机构动力学模型,将MATLAB/Simulink与Carsim联合仿真,建立线控四轮转向整车模型;基于二自由度模型分析横摆角速度和质心侧偏角对汽车稳定性的影响,推导理想的横摆角速度和质心侧偏角;以横摆角速度增益恒定为依据设计理想传动比,得到期望前轮转角,以横摆角速度误差为控制量设计模糊控制器得到附加前轮转角对期望转角实时修正,实现前轮主动转向;针对横摆角速度和质心侧偏角与理想值之间的误差,加权得到稳定性控制目标;设计自适应积分滑模反馈控制策略输出后轮转角,对理想值进行跟踪,实现后轮主动转向。结果 仿真实验结果表明：所搭建的线控转向系统能够准确反映汽车动力学特性。相比无控制的机械前轮转向汽车与横摆反馈控制的四轮转向汽车,线控主动四轮转向汽车在双移线工况下将质心侧偏角控制在0值附近波动,横摆角速度跟踪误差控制在1.149 deg/s以内;在角阶跃工况下将质心侧偏角稳态值控制在0.065 deg,横摆角速度稳态值误差为0.074 deg/s。结论 线控...

Research on Control Strategy of Active Four-wheel Steer-by-wire Vehicle

Objective Aiming at the problems of insufficient lateral stability and poor control robustness of the four-wheelsteering vehicle with the steer-by-wire system an active steering feedback control strategy was proposed. Methods Thedynamic model of steering actuator of steer-by-wire system was built in Simulink and the vehicle model of steer-by-wiresystem was established by co-simulation of MATLAB / Simulink and Carsim. Based on the two-degree-of-freedom model the influence of yaw rate and sideslip angle on vehicle stability was analyzed and the ideal yaw rate and sideslip anglewere derived. The desired front wheel angle was obtained by designing the ideal transmission ratio based on the constantyaw rate gain and the fuzzy controller was designed with the yaw rate error as the control variable to obtain the real-timecorrection of the additional front wheel angle to the desired angle so as to realize the active steering of the front wheel.Aiming at the error between the ideal values and the actual yaw rate and sideslip angle the stability control target was obtained by weighting. The adaptive integral sliding mode feedback control strategy was designed to output the rear wheelangle to track the ideal value and realize the active steering of the rear wheel. Results The simulation results show thatthe established steer-by-wire system can accurately reflect the dynamic characteristics of the vehicle. Compared with theuncontrolled mechanical front-wheel steering vehicle and four-wheel vehicle with yaw-rate-feedback steering control thesteer-by-wire active four-wheel steering vehicle controls the sideslip angle to fluctuate around 0 under the double lanechange condition and controls the yaw rate tracking error to be within 1. 149deg / s. Under the angle step condition thesteady-state value of the sideslip angle is controlled at 0. 065 deg and the steady-state error of the yaw rate is 0. 074 deg / s.Conclusion The active four-wheel steer-by-wire control strategy has remarkable control effects and good robustness underdouble lane change and angle step conditions which effectively improves the handling stability and active safety of thevehicle.