Robust Steering Angle Tracking Control for Steer-by-wire System

Improving the steering angle tracking performance of the steer-by-wire (SBW) system is crucial to vehicle maneuverability and driving safety. However, due to complex disturbances caused by velocity-dependent tire-road contact characteristics, lagged sensor signals and unmodeled steering dynamics, enhancing the robustness, improving the system bandwidth and minimizing the system overshoot pose significant challenges in the steering angle tracking controller scheme. Compared with conventional cascade angle-speed-current control scheme, robust control strategy is proposed to achieve better transient response and stead-state response in this paper. Firstly, the proposed algorithms are simulated and analyzed using an elaborate steering dynamic model with the dynamic friction model and sensor model. Step and sine wave tests in the Simulink platform are performed using the proposed algorithms and conventional algorithms, respectively. Then, the steering angle tracking control algorithms are deployed into the steering execution motor power pack and validated in a SBW prototype vehicle, and a random city driving test is accomplished. Finally, simulation-based and experimental results are presented to demonstrate the effectiveness of the proposed control algorithms.