In the integrated system of electric power steering (EPS )and active front steering (AFS ),the additional front wheel rotating angle generated by AFS gives rise to the change of tyre lateral force,it leads to the change of steering wheel torque finally.Although the tyre force is hard to be measured directly,it can be estimated using the extended Kalman filtering (EKF)algorithm.This method can solve the problem of steering wheel torque change.Here,a vehicle nonlinear mathematical model was presented and a nonlinear tyre lateral force estimator was also established based on EKF.The estimated tyre lateral force was used to compensate the abrupt change of steering wheel torque and to realize the combination of vehicle state estimation and vehicle control.The simulation analysis with MATLAB /Simulink verified the effectiveness of the proposed control strategy.%对融合了主动前轮转向的电动助力转向系统，主动转向引入的附加转角使得轮胎侧向力发生突变，从而导致转向盘力矩会发生突变。虽然轮胎力不易直接测量，但是扩展卡尔曼滤波算法可以实现对非线性轮胎力的估计，为解决转向盘力矩突变找到实现方法。建立了非线性车辆数学模型，并构建基于扩展卡尔曼滤波算法的轮胎侧向力观测器，根据得到的轮胎侧向力的估计值对转向盘力矩突变进行补偿，实现了车辆状态估计与车辆控制的结合。在 MATLAB／Simulink 里的仿真分析验证了控制策略的有效性。
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