Theoretical And Experimental Research On Vehicle Magnetorheological Semi-active Suspension System

The two key technologies of magnetorheological (MR) semi-active suspension system are still immature. The present mathematic models of MR dampers have common limitation that either it is simple but imprecise, and can't reflect hysteretic characteristic of dampers, or it is accurate but too complex to conduct control conveniently. Meanwhile, there are the same problems for control strategy. Effect of a strategy won't be good enough if it is simple, while a complex control scheme usually utilizes complex automatic control theory and is large difference from the real conditions, and can only be verified by simulating but can't be by experiment. Therefore, taking accurate and simple as a goal, the MR semi-active suspension system has been researched. The main contributions and innovation conclusions of the dissertation include the followings:(1) A composite polynomial model of MR dampers has been proposed after damping characteristic experiments have been conducted on a MR damper. The affections of amplitude and frequency are considered in this model which can accurately reflect current saturation behavior. Comparing numerical simulation with experiment data, it is verified that this model can more accurately reflect the real engineering conditions compared with the common polynomial model.(2) A quarter-car suspension mechanical test rig has been set up, and based on virtual instrument system, the real time control experiment platform of MR suspension system in universal use has been set up, and it lays foundation on developing rapid control prototyping.(3) A new model reference sliding mode controller for semi-active suspension system has been presented. The proposed controller is easy to be carried out and eliminates the necessity of road signal as well as measuring damping force. The controller uses an approximate ideal skyhook system as a reference model, and generates an asymptotically stable sliding mode in the error dynamics between the plant and the reference mode states. A simulation study and the rapid control prototyping experiments have been performed, and results show that compared to passive suspension, practical control and fuzzy logical control, the proposed controller shows better integrated performance, and should be directly transferable to commercial semi-active vehicle suspension implementations.