Active Robust Tracking Control Based Linear Disturbance Estimator for Steer-by-Wire Systems

This paper explores the control of steer-by-wire (SbW) systems. It relies entirely on steering actuation due to the absence of a physical transmission mechanism. A major challenge in tracking control for SbW actuation is the nonlinear rack force resulting from tire-road interactions. To address this issue and enhance steering performance, we propose a novel steering controller incorporating active rack force compensation within the tracking control algorithm. The effectiveness of rack force estimation is demonstrated using a simple linear disturbance estimator and a low-pass filter. Furthermore, an active tracking controller with feedforward compensation is developed by integrating this linear disturbance estimator into a robust sliding mode control framework, improving the overall stability and responsiveness of the SbW system. Finally, the practical effectiveness and robustness of the proposed algorithms are rigorously validated through extensive Simulation-in-the-Loop experiments, utilizing diverse driving test cycles benchmarked against international ISO standards.