Control Of Vehicle Semi-active Suspension Based On MR Damper

The suspension system is a critical component that can influence the vehicular performance. The intelligent suspension system has real-time control according to the road surface conditions and the state of vehicle's motion. Its adoption is an important approach to improving comfort and security. Magnetorheological (MR) semi-active suspension applies MR technology to carry out the real-time control of its damp. Due to its good controllability, wide dynamic range, rapid response speed, low operating power requirement and comparatively simple structure, MR semi-active suspension has become one of the central research subjects in intelligent suspension field, and has also received considerable attention.In this paper, the methods and dynamical characteristics of MR damper are applied to study the suspension, the control strategies and the control system's design. The main contributions of the dissertation include the following:1. The paper expounds the significance of the intelligent suspension research reviews its history and development, summarizes the present situation and existing problems of MR fluids, MR dampers and MR semi-active suspension and puts forward the main work aimed at the present problems of vehicular MR semi-active suspension.2. Based on the analysis of nonlinear characteristics of vehicular suspension system, this dissertation deals with the semi-active suspension control on basis of proposed Magnetorheological (MR) damper model and the two-degree of freedom (2-DOF) 1/4quarter-vehicle model. The MR semi-active suspension model is established. The method of control strategy on differential geometry theory and fuzzy control strategy is expounded. The differential geometry controller and the fuzzy controller are designed. MR semi-active suspension simulation system is established by using Matlab software and its corresponding toolboxes. After adopting the above control strategies, the time domain response of semi-active suspension are analyzed by using numerical simulation. The comparison and evaluation between the two different control strategies are carried out according to the control effects.3. Compared with two semi-active suspensions based on MRD and on-off control damper, respectively, the simulation results indicate that the nonlinear control strategies based on MRD are more feasible in allusion to the existing elements of semi-active suspensions with nonlinear characteristics. So these control strategies can not only attain an excellent effect on weakening vehicle vibration and disturbance, but also coincide with the practical condition.4. Finally, the simulation results from the two nonlinear control methods were compared, which showed that the suspension controlled by the fuzzy logic method had less impact response and lower vibration intensity than that by the differential geometry theory strategy, and had superior performance.