极限工况下无人驾驶四轮转向汽车横向跟踪控制策略

Lateral tracking control of a driverless four-wheel steering vehicle under extreme conditions

为了提高无人驾驶四轮转向汽车在不同路面附着系数的极限工况下轨迹跟踪精度,提出了一种轨迹跟踪控制策略。建立车辆三自由度动力学模型作为控制器预测模型,基于模型预测控制理论设计前轮转向控制器,考虑质心侧偏角对车辆稳定性的影响,基于模糊控制理论设计后轮转向控制器。在Matlab/Simulink和CarSim软件平台中建立联合仿真模型,选取高速高附着转弯工况和中速低附着的转弯工况进行对比试验。结果表明:考虑质心侧偏角的后轮转向控制器保证无人驾驶四轮转向汽车高速转向稳定性的同时,比未考虑质心侧偏角的后轮转角控制器轨迹跟踪精度提高约25%。

In order to improve the trajectory tracking accuracy of driverless four-wheel steering vehicles under extreme conditions of different road adhesion coefficients, this paper proposes a trajectory tracking control strategy. A vehicle three-degree-of-freedom dynamic model is established as the controller prediction model and the front wheel steering controller is designed through predictive model control theory. Considering the effect of the center-of-mass slip angle on vehicle stability, a rear wheel steering controller is designed based on the fuzzy control theory. A co-simulation model is established in Matlab/Simulink and CarSim software platforms. The high-speed turning condition on high-adhesion roads and the medium-speed turning condition on low-adhesion roads are selected for comparative experiments. The results show that, considering the center-of-mass slip angle, the rear wheel steering controller ensures the high-speed steering stability of the driverless four-wheel steering vehicle. At the same time, compared with the rear wheel angle controller without considering the center-of-mass slip angle, the trajectory tracking accuracy improves about 25%.