A Super-Twisting sliding mode control combined with a fuzzy logic scheme for improving electric power steering performance

Abstract

This paper presents the design of a robust control mechanism that integrates the Super-Twisting Sliding Mode Control with a fuzzy logic scheme (FSTSMC). The selected control law mitigates chattering effects while maintaining a simple structural form. The theoretical stability of the closed-loop system is examined using Lyapunov criteria to guarantee convergence. The control parameter is adjusted through a fuzzy mechanism with two inputs to improve the system’s adaptability to parameter uncertainties, which are typically neglected in conventional control law design. Numerical simulation results demonstrate that the proposed controller achieves superior tracking performance compared with conventional SMC. Specifically, the Root Mean Square (RMS) tracking error does not exceed 0.04% in the absence of parameter uncertainties and remains below 3.55% when uncertainties are considered, except for the motor current (5.867%). In addition, the proposed scheme significantly suppresses chattering, which is still seen in conventional SMC.