基于状态反馈的四轮转向汽车LQR优化控制

为了提高汽车的操纵稳定性,以4轮转向(4WS)汽车为研究对象,建立了2自由度系统的数学模型和状态方程。并以横摆角速度和侧偏角为优化目标,设计了线性二次型调节器(LQR)。通过质心侧偏角和横摆角速度的共同反馈,控制汽车后轮转角,实现4WS控制。在MATLAB/Simulink环境下完成了传统前轮转向汽车、零侧偏角比例控制及LQR控制的4WS汽车仿真。结果表明,相对于其他控制策略,基于状态反馈的LQR优化控制能够改善汽车的操纵稳定性,但不能够既将汽车的质心侧偏角降到基本为零,同时又保证横摆角速度处于理想状态。因此,汽车动力学集成控制将是未来汽车发展的重要方向。

LQR Control of Four-wheel Steering Vehicle Based on State Feedback

A two degree - of - freedom Four - Wheel Steering （4WS） vehicle is investigated to improve the handling stability. The mathematical model and state equation of 4WS system are established, and a linear quadratic regulator （LQR） controller is proposed. The rear wheel angle is controlled by the feedback of the sideslip angle and yaw rate. The conventional front - wheel steering vehicle, LQR controlled 4WS vehicle as well as proportional controlled 4WS vehicle are simulated with MATLAB/Simu- link. The simulation result shows that the LQR strategy can help to improve the handling stability compared to other strategies. But both the sideslip angle and yaw rate cannot reach ideal states simultaneously with any control strategy if only the front and rear wheels are controlled, which points out that the integrated control of vehicle dynamics will be the future for vehicle technology.