A study on a nonlinear combined dual objective control strategy for active suspension systems

Abstract The active suspension system faces an inherent conflict between body acceleration and suspension deflection: reducing body acceleration to improve comfort often results in increased suspension deflection, while suppressing suspension deflection to enhance stability may exacerbate body vibrations. To address this issue, a nonlinear dual-objective cooperative control strategy is proposed in this paper, which enhances the overall performance of the active suspension system by coordinating conflicting control terms. For body dynamics, a specialized quasi-sliding mode control method is employed, utilizing body acceleration information to reduce body acceleration and regulate body displacement. Meanwhile, for the faster-changing suspension deflection dynamics, a saturated PD sliding mode tracking control term is introduced to regulate suspension deflection and counteract disturbances in the suspension deflection. Based on Lyapunov stability theory, the finite-time convergence of the closed-loop system is proven. A comparative analysis with the nonlinear disturbance observer (NDO) method reveals that the proposed control scheme achieves excellent control performance while reducing the control input by more than 50%. The effectiveness of the designed control scheme is verified through simulations and experiments. Multiple results demonstrate that the designed controller can achieve improved active suspension performance with smaller control inputs, including reducing body acceleration by more than 40% and more effectively regulating suspension deflection.