Observer-based control of vehicle semi-active suspensions

Abstract

This paper presents an observer-based controller for vehicle semi-active suspensions. Vehicle suspensions are disturbance-affected dynamic systems and semi-active suspensions can be represented as a bilinear model. A new methodology for designing observers for vehicle semi-active suspensions has been proposed. The proposed methodology simplifies the observer design process and is convenient for implementation. An observer is formulated such that the estimation error is independent of unknown road disturbances. The proposed observer uses easily accessible measurements, such as accelerations, and guarantees exponentially convergent state estimations for suspension deflections and velocities. The absolute sprung mass and unsprung mass velocities can be estimated using the proposed observer. Simulations and experimental rig tests show that all states of a semi-active suspension can be estimated only with acceleration measurements. The estimated states are used to improve ride quality in a semi-active suspension. It has been shown that the performance of the observer-based controller is comparable to that of a controller using measured states.