Improved adaptive fuzzy sliding-mode control for seat suspension based on magnetorheological fluid (MRF) damper

Abstract. This paper introduces an improved adaptive fuzzy sliding-mode control approach for semi-active seat suspension utilizing magnetorheological fluid (MRF) dampers. Firstly, the damping characteristic of the MRF damper was tested, and the dynamics model of MRF damper was established. Secondly, the 5-degree-of-freedom “human-seat” suspension system model was built and adaptively simplified, and a suitable adaptive control law was designed to estimate the perturbations generated during the simplification process of the human-seat model online. Based on the simplified model, a fuzzy algorithm was adopted to optimize the approach rate parameters in the sliding-mode control so as to improve the robustness of the system while guaranteeing the approach rate, and hyperbolic tangent function was employed to replace the sign function in the switching term to make the system more continuous during the switching process, which effectively reduces the “chatter” problem in the sliding-mode control. Thirdly, the dynamics model of the MRF damper is added into the sliding-mode control model to ensure the effectiveness of the MRF damper output control force. Finally, the effectiveness of the improved adaptive fuzzy sliding-mode control method was confirmed through simulation, demonstrating its capability to significantly reduce seat acceleration and suspension dynamic deflection under different working conditions compared with passive damping, skyhook control, and sliding-mode control.