Abstract:

A dynamic model of the active front steering (AFS) system was built using the Lagrange dynamics, and a linear quadratic regulator (LQR) controller
was designed by taking the steering wheel angle, yaw rate and sideslip angle as the optimization object. In the controller, the motor angle was controlled by the feedback of the yaw rate and the sideslip angle. Additionally,a state-space observer was designed to estimate the sideslip angle, which was difficult to measure directly.Simulation results in MATLAB show that the LQR control can improve the steering characteristics and handling stability effectively.

Key words: active front steering(AFS)；state-space observer； linear quadratic regulator(LQR)； handling stability

摘要：

应用拉格朗日方程建立汽车主动前轮转向的动力学模型，并以转向盘转角、横摆角速度和侧偏角为优化目标，设计线性二次型调节器（LQR）。调节器中，通过横摆角速度和侧偏角的共同反馈控制助力电机的转角。由于质心侧偏角信号难以直接测量，设计了状态观测器对该信号进行估计。通过MATLAB进行仿真计算，结果表明， LQR优化控制能有效地改善整车的转向特性，提高汽车的操纵稳定性。

关键词: 主动前轮转向(AFS);状态观测器;线性二次型调节器(LQR);操纵稳定性