四轮主动转向的模型跟踪控制

Model Following Control of Four-Wheel Active Steering Vehicle

在分析了传统四轮转向不足的基础上,将前轮主动转向与后轮主动转向相结合,提出了四轮主动转向(4WAS)控制,独立地控制前后轮转向角.采用前馈控制和反馈控制相结合跟踪参考模型的控制策略,并基于最优控制理论设计了反馈控制器,使实际车辆模型输出与期望参考模型输出之间的跟踪误差最小.基于3自由度车辆模型在Matlab中进行了仿真研究.结果表明,与传统的四轮转向和前轮转向相比,采用模型跟踪控制策略的4WAS控制能够同时实现期望的车辆横摆角速度和质心侧偏角响应,提高了中、高速时车辆的操纵稳定性.

Based on the analysis of deficiency of conventional four-wheel-steering, a four-wheel active steering （4WAS） control was proposed which combines the front wheel active steering and rear wheel active steering. The strategy of combining feedforward control and feedback control was adopted to follow the desired performance of reference vehicle model. A feedback controller was designed based on the optimal control theory, minimizing the tracking errors between the outputs of actual vehicle model and that of ref- erence vehicle model. Finally, computer simulation based on a three degree-of-freedom vehicle mode was used to examine the performance of 4WAS vehicle. The simulation results indicate that,compared with the conventional four-wheel steering and front wheel steering, the proposed 4WAS with model following control can achieve the desired yaw rate and vehicle sideslip angle response simultaneously and improve the vehicle handling and stability in middle and high speed.