Development of a Hybrid Control Algorithm Based on a Combination of Robust Nonlinear Techniques for Electric Power Steering

This work proposes a hybrid nonlinear control algorithm for electric power steering (EPS) systems, designed by integrating backstepping control (BSC), sliding mode control (SMC), and proportional-integral (PI) control. The robustness of SMC against external disturbances and the flexible trajectory handling of BSC are combined to achieve high-performance control. Meanwhile, PI controllers compensate for phase differences and tracking errors. Their gains are optimally tuned using a dual-loop optimization framework, which is later extended with fuzzy logic to enhance adaptability under varying operating conditions. System stability is rigorously analyzed and proven via Lyapunov theory. A dynamic EPS model is developed to account for disturbances (road reaction torques and external disturbances). Numerical simulations validate the proposed method, showing that the maximum tracking error remains below 0.01 rad, with root mean square error (RMSE) approaching zero. The proposed controller effectively suppresses chattering and eliminates phase lag, ensuring robust and precise steering assistance under various driving conditions.