Path tracking precision is fundamental for safe and autonomous driving of intelligent vehicles.To address the problem of chattering in sliding mode control Systems and enhance the control precision of path tracking controllers,a novel PID Integral Sliding Mode Control strategy with Activation Function (PIDSM-AF) is proposed.Firstly,based on a two-degree-of-freedom vehicle model,the vehicle dynamics model is decomposed into a lateral deviation one to establish the lateral control model.Subsequently,an integral sliding mode surface incorporating both heading angle deviation and lateral deviation is constructed employing the extremum method.Considering the system chattering that is difficult to eliminate by general exponential approaching rate,a nonlinear activation function is introduced to adjust the rate when the system state is close to the sliding surface on the basis of an improved exponential approaching rate.This leads to the design of a lateral path tracking controller based on sliding mode control with an activation function.Finally,the improved sliding mode controller is subjected to double lane change tests through Carsim／Simulink co-simulation.The results show that,compared with traditional terminal sliding mode controller,the maximum lateral deviation of the optimized integrated sliding mode controller is reduced by about 64％ and 34.9％,and the average lateral deviation is reduced by about 68.4％ and 59.7％,under the conditions of low-speed low-adhesion and high-speed high-adhesion conditions,respectively.Furthermore,the optimized controller effectively suppresses the chattering and overshoot changes of vehicle heading angle and front wheel rotation angle,demonstrating strong robustness.