In order to reduce the adverse effects of internal uncertainty and external disturbance in the active front steering (AFS) system of electric vehicles, two chattering-free discrete-time sliding mode (CDSM) AFS controllers are proposed in this paper. First of all, the sideslip angle is estimated by constructing a Luenberger observer and a two-degree-of-freedom model-based parameter tuning scheme is proposed to simplify the parameter tuning. On this basis, the first-order disturbance difference is imposed on the CDSM controller to reduce the disturbance estimation error. Secondly, in order to further improve the control accuracy, a generalized proportional integral observer (GPIO) is constructed and its stability is verified by the algebraic equations. Finally, a new composite CDSM controller is obtained with the aid of GPIO to further improve the control performance. The feasibility and effectiveness of the proposed methods are verified by simulations.

为了减少电动汽车主动前转向（AFS）系统内部不确定性和外部干扰的不利影响，本文提出了两种无颤振离散时间滑模（CDSM）AFS控制器。首先，通过构建Luenberger观测器估计侧滑角，并提出了基于二自由度模型的参数调整方案以简化参数调整。在此基础上，对CDSM控制器施加一阶扰动差以减小扰动估计误差。其次，为了进一步提高控制精度，构建了广义比例积分观测器（GPIO），并通过代数方程验证了其稳定性。最后，借助GPIO获得了一个新的复合CDSM控制器，进一步提高了控制性能。通过仿真验证了所提出方法的可行性和有效性。