A Composite Internal Model Robust Control Strategy for an Automobile Steer-by-wire System

In this paper, a composite Internal Model Robust Control (IMRC) strategy based on an automobile Steer-by-wire (SBW) system is proposed to improve the performance for active steering. A mathematical model of SBW system is built. A two-degree-of-freedom Internal Model Controller (IMC) optimized by Particle Swarm Optimization (PSO) algorithm is designed for the SBW actuator system to track the desired front-wheel steering angle. Simulations are carried out to verify the effectiveness of IMC controller and the results demonstrate that the IMC controller is able to provide better control performance compared with a PID controller optimized by PSO algorithm. Besides, a Generalized Internal Model Robust Controller (GIMRC) based on the improved Youla parameterization is designed to track the desired yaw rate of controlled vehicle and improve the robustness against parameter uncertainties and external disturbances. Open-loop simulations are carried out to verify the effectiveness of GIMRC controller and the results demonstrate that desired yaw rate can be accurately tracked in different driving conditions. Then co-simulation is carried out via MATLAB/Simulink and CarSim to verify the effectiveness of the composite strategy. The results indicate that better handling and stability performance can be obtained for the automobile SBW system combining the proposed strategy.