基于状态估计的无人车前轮转角与横摆稳定协调控制

针对无人车轨迹跟踪问题，提出了一种基于状态估计的无人车前轮转角和横摆稳定协调控制策略.建立了车辆轨迹跟踪模型，利用模型预测控制算法设计了轨迹跟踪控制器，得到实时跟踪参考轨迹所需的前轮转角.根据车辆模型设计了一种基于未知输入观测器的前轮转角估计方法，并将估计结果作为前轮转角跟踪控制的输入量.基于非奇异终端滑模控制设计了前轮转角跟踪方法，通过转向电机扭矩来控制车辆转向以实现轨迹跟踪.同时，设计了车辆横摆稳定控制器，通过控制横摆角速度跟踪误差确保车辆横摆稳定.建立了CarSim-Simulink联合仿真模型并进行仿真实测试.结果表明，未知输入观测器具有较好的前轮转角估计效果，从而为车辆协调控制提供可靠信息源，协调控制策略能够在保证车辆横摆稳定性的同时完成车辆轨迹跟踪. 

Coordinated Control of Front-Wheel Steering Angle and Yaw Stability for Unmanned Ground Vehicle Based on State Estimation

Aiming at the trajectory tracking problem of unmanned vehicle, a coordinated control strategy of front-wheel steering angle and yaw stability was proposed for unmanned vehicle based on state estimation. Firstly, a vehicle trajectory tracking model was established, and a trajectory tracking controller was designed with the model predictive control algorithm to obtain the front-wheel steering angle required of tracking reference trajectory in real time. And then, according to the vehicle model, a method of front-wheel steering angle estimation based on unknown input observer was designed and the estimation result was used as the input of front-wheel steering angle tracking control. Based on the nonsingular terminal sliding mode control, a front-wheel steering angle tracking method was designed, and the trajectory tracking was realized by the torque control of steering motor. At the same time, a vehicle yaw stability controller was designed to ensure the vehicle yaw stability by controlling the yaw rate tracking error. Finally, a CarSim-Simulink co-simulation model was established and used for simulation test. The results show that, the unknown input observer has a better effect on front-wheel steering angle estimation, which provides a reliable information source for vehicle coordinated control. And the coordinated control strategy can ensure the vehicle yaw stability and complete the vehicle trajectory tracking at the same time.