Fuzzy Sliding Mode Control for a Nonlinear System With an Extended State Observer

ABSTRACT This paper presents a fuzzy‐based sliding mode controller (SMC) that incorporates an extended state observer (ESO) to achieve accurate trajectory tracking of uncertain nonlinear systems. Conventional SMCs are robust, but suffer from chattering, whereas ESO‐based control improves disturbance rejection but remains gain‐sensitive. To simultaneously reduce chattering and improve uncertainty compensation, this paper integrates a Sugeno‐type fuzzy inference system with an ESO to adaptively tune the switching gain based on the sliding surface. This allows robust tracking while enhancing convergence speed, control smoothness, and estimation accuracy. To prove the effectiveness of the proposed method, a comparative analysis has been conducted between conventional SMC, fuzzy sliding mode control (FSMC) without ESO, and the proposed FSMC with ESO to evaluate transient and steady‐state performance. The simulation results show that all other controllers achieve trajectory tracking; however, the proposed controller outperforms the others in terms of accuracy and convergence speed. Quantitatively, the proposed controller achieves the shortest settling time, negligible overshoot, and near‐zero steady‐state error compared to other methods. In addition, a sensitivity analysis is performed to evaluate robustness against observer gain variations of . The results demonstrate that the proposed controller maintains accurate state and disturbance estimation under significant parameter variations, confirming strong robustness.