Robust stabilization of underactuated active suspension system via high-order fully actuated system theory

Abstract

To address the inherent underactuation of active suspension systems under bounded external disturbances, a robust ride quality control strategy is developed within the high order fully actuated (HOFA) system framework. Departing from conventional active suspension controllers formulated in a first-order state-space framework, this study revisits the problem from the perspective of high-order system dynamics. By incorporating auxiliary control inputs, the original high-order suspension dynamics are structurally decoupled and reformulated into an equivalent fully actuated form. Based on the reconstructed fully actuated model and employing the direct parameter method within the HOFA framework, a robust stabilization controller for vehicle ride comfort regulation is devised while attenuating bounded external disturbances via a robust compensatory term. The proposed framework preserves the system’s high-order physical properties and enables explicit controller design, significantly simplifying the control structure and stability analysis. Furthermore, rigorous Lyapunov-based analysis theoretically guarantees the global stability of the closed-loop system, with all state variables converging to an arbitrarily small neighborhood of the desired equilibrium. Finally, extensive numerical simulations, corroborated by analytical investigations, confirm the validity and superior performance of the proposed method.