Semi-active control of automotive suspension systems with magnetorheological dampers

Vibration in today's increasingly high-speed vehicles including automobiles severely affects their ride comfort and safety. The objective of this paper is to develop and study automotive suspension systems with magneto-rheological (MR) fluid dampers for vibration control in order to improve the passenger's comfort and safety. A two degree-of-freedom quarter car model is considered. A mathematical model of MR fluid damper is adopted. In this study, a sliding mode controller is developed by considering loading uncertainty to result in a robust control system. Two kinds of excitations are inputted in order to investigate the performance of the suspension system. The vibration responses are evaluated in both time and frequency domains. Compared to the passive system, the acceleration of the sprung mass is significantly reduced for the system with a controlled MR damper. Under random excitation, the ability of the MR fluid damper to reduce both peak response and root-mean-square response is also shown. The effectiveness of the MR suspension system is also demonstrated via hardware-in-the-loop simulation. The results of this study can be used to develop guidelines to effectively integrate automotive suspensions with MR dampers.