Active Vibration Control for Suspension in Consideration of Limitation on Stroke Displacement

When large external forces come from road, a suspension stroke reaches the limitation and the riding comfort may reduce. In order to overcome this problem we propose a new control method for an active suspension which can avoid reaching the stroke limitation. A sliding mode controller is designed in consideration of rigidity variation of the spring. Also in order to estimate the internal state of the suspension, VSS (Variable Structural System) observer is designed without information of nonlinear force which occurred in rigidity variation when the suspension reaches the stroke limitation. By carrying out simulation and experiment of a quarter-car suspension model it is verified that the performance of the controller is superior to that of the method, which switches to a passive damper near the stroke limitation from LQR (Linear Quadratic Regulator) in the range of small stroke.