Computer control algorithm for semi-active suspensions based on a two-wheel vehicle model

Abstract

Most current control algorithms for semi-active suspensions are developed based on a quarter-car model, which considers every wheel of an automobile as independent of the others. This means that only the vertical translation motions of wheels are considered during suspension operation. When the rotational motions (roll, yaw and pitch) are not negligible, these semi-active suspension controllers may not provide good performance. For some physical suspension systems (such as truck and train suspensions), the yaw and roll motions are not significant compared to the pitch motion. The development of semi-active controllers for such suspension systems should be sufficient if the pitch motion is considered as well as the vertical translation motions. In this paper, a two-wheel semi-active suspension system is modelled as a multiple-input bilinear system. Based on this model, a suboptimal controller is developed to minimise a quadratic performance index. Simulation results show that this suboptimal controller performs much better than passive systems.