Research on Control Algorithm for Active Rear Wheel Steering System of Passenger Cars

With the continuous advancement of automotive technology, the active rear wheel steering system, serving as a crucial component for enhancing vehicle handling performance and safety, has garnered extensive attention. In this paper, the control algorithm and performance optimization of the active rear wheel steering system are deeply studied. Firstly, a complete vehicle dynamics model is established, providing a theoretical foundation for the research on control algorithms. Subsequently, the optimal control theory is adopted to achieve the control of the rear wheel steering angle, and the LQR control strategy with variable weight coefficients is proposed in response to the linear and nonlinear variations of the vehicle tire sideslip characteristics. Finally, taking the 2WS vehicle, the proportional steering control strategy for the front and rear wheels, and the proportional feedforward + yaw rate feedback control strategy as references, modeling and joint simulation based on the CarSim software are employed to conduct comparative simulation verification of the LQR control strategy with variable weight coefficients. Through the objective and quantitative evaluation of the simulation results, the vehicle controlled by the LQR with variable coefficients exhibits remarkable control effects in scenarios such as the angular step condition, double lane change condition, the limit double lane change condition on low-adhesion road surfaces, and the lateral wind condition, all achieving the control objectives. Furthermore, this algorithm can enhance the stability and active safety of the vehicle.