Output feedback based sliding mode control of active suspension using backstepping

The presence of nonlinearity in the dynamics of a suspension system equipped with a hydraulic actuator and faced with road perturbations makes its control difficult. To provide an effective control action, a robust observer based output feedback control is proposed. For the estimation of the states in the presence of nonlinearities and perturbations a High Gain Observer is first designed. Employing the estimated system dynamics, an integral sliding mode control based on the back-stepping technique is then derived. The closed loop stability is analyzed under Lipschitz conditions for the nonlinearities.