A robust control strategy based on disturbance rejection control and smooth sliding mode with fuzzy-tuned sigmoid function for electric stabilizer bars

Abstract

Vehicle rollover instability becomes critical during sharp steering at high speeds. While Sliding Mode Control (SMC) is widely adopted for its robustness, its inherent chattering significantly deteriorates control smoothness and actuator durability. This article proposes a novel integrated control strategy that combines Disturbance Rejection Control (DRC) with a smooth SMC law shaped by a fuzzy-tuned expanded sigmoid function to enhance the performance of electric stabilizer bars. Unlike conventional SMC- or ESO-based approaches, the proposed method provides several significant advantages: (i) suppresses chattering through an adaptive sigmoid function whose slope is dynamically tuned by a fuzzy mechanism, (ii) improves disturbance estimation accuracy via an LESO integrated in the DRC framework, and (iii) enhances adaptability under varying driving conditions without relying on fixed control gains. Simulation results demonstrate clear performance improvements: the maximum roll angle is reduced from 8.110° (without bars) to 5.975° using the proposed control, and the minimum vertical tire force increases from 327.436 to 2937.274 N. Chattering amplitude in the control input is reduced by approximately 98% (Root Mean Square value) compared with conventional SMC, effectively eliminating high-frequency oscillations. These findings confirm that the proposed control provides a more stable, smoother, and disturbance-resilient anti-roll control solution suitable for practical implementation.