Second order sliding mode control of active suspension system with supertwisting algorithm and disturbance observer

Designing the controller for active suspension system is the topic of great interest among the control engineers since long to provide the ride comfort to the passengers under the rough and uneven road surface. In this paper, a super twisting control algorithm of second order sliding mode controller is designed and implemented on the quarter car system. The super twisting algorithm attenuates the chattering in the control input applied to the actuator which reduces the energy applied to the active suspension system. However the efficacy of super twisting algorithm can be greatly enhanced if the knowledge of the uncertainties/disturbances can be estimated and removed before it reached to the plant. A disturbance observer is used to estimate the disturbance in prior which improves the performance of the system. The stability of the system is also proved with the Lyapunov function. The efficacy of the designed controller with disturbance observer is shown with simulation and experimental results.