Theoretical and Experimental Investigation of Magneto-Rheological Damper Based Semi-Active Suspension Systems

Semi-active vehicle suspension systems with Magneto-Rheological (MR) dampers have recently received an increasing attention. Satisfactory performance of these systems is highly dependent on the adopted control method. This paper offers theoretical and experimental investigation of the control of vehicle suspension systems using a quarter car suspension equipped with a MR damper. To achieve the best performance, a control method made of two nested controllers is used. Fuzzy logic, skyhook and On-Off control techniques are studied as system controllers in conjunction with a Heaviside step function as the damper controller. For the theoretical study, the modified Bouc-Wen model of MR dampers is used to calculate the damping force and a mathematical model of the semi-active quarter car suspension is derived and used in the simulation. To prove the applicability of the proposed fuzzy logic controller in a real suspension system, a two degrees of freedom quarter car test rig is designed and used. To quantify the effectiveness of the system under bump and random road disturbance, various performance criteria are evaluated based on the dynamic response of the quarter car suspension system in time and frequency domains,. Simulation and experimental results from the system with the fuzzy logic controllers are compared to the results from the system with skyhook controller, On-Off controller, a passive MR damper and a conventional passive damper.