Abstract: A sliding mode control with disturbance observer integrating skyhook model (RMDOSMC) was proposed to improve the performance of active suspension systems (ASSs)． The uniform boundedness and uniform ultimate boundedness of ASSs were proved． The sprung mass displacement and speed of skyhook model can provide refe-rence trajectory for that of the sprung mass in ASSs． The disturbance observer is designed for estimating uncertain-ties in ASSs，which are external disturbance force acting on the sprung mass and parameters of suspension stiffness and damping． Under the road excitation of step and random，experimental results were presented to validate the ef-fectiveness of the proposed approach． Furthermore，under the road excitation of step，the performance indexes，in-cluding acceleration of the sprung mass，the suspension deflection and the dynamical load of tire，were calculated by using the linear quadratic optimal control ( LQR)，the sliding model control with disturbance observer (DOSMC) and the proposed control． Compared with the linear quadratic optimal control and the sliding mode con-trol with disturbance observer，ASSs with the proposed control can obtain better performance indexes．

Key words: active suspension system, skyhook model, sliding mode control, disturbance observer