Simulation And Analysis Of Semi-active Suspension Based On Fuzzy Control And Controllable Damping Shock Absorber

With the development of Automobile industry, the vibrationcontrol of the vehicle suspension system is always an important problemin the world. The passenger ride comfort and handling and stability istwo of the main performance indexes of vehicle, which is relateddirectly to the quality of vehicle suspension. The vehicle suspensionsystem is divided into three styles, that is passive suspension,semi-active suspension and active suspension.Traditional vehicle suspension system is passive control system.It is Designed for certain special road surface and vehicle riding state,which Vibration damper shave fixed damping characteristic .When theroad surface and vehicle riding state overage the design conditions,the damping effect of the passive control system will be depressed. Thestructure of complete active control method is complex and its cost high.Contrast with complete active control, semi-active control is moreinexpensive and its structure simpler. Semi-active control is fit forsuppressing the vibration of vehicle suspension system.People now pay more attention on semi-active suspension becauseit has the simple structure and does not use up the vehicle's energy.The thesis studied preliminarily on the semi-active suspension and howto let the shock absorb has a good character and finds a better controlmethod is the main problem in the suspension research at present.First, the thesis studied the method of building the damperforce-velocity model, which looked the configuration parameter ofhydraulic damper as model parameter.The flow function was from the damper flow experiment. A more accuratenonlinear mathematical model was set up through analyzing the damper'smovement, and using step motors or Electro-magnet as the control valveof the adjustable damper was proposed, and its mathematical model wasestablished. An experimental verification based on damper has been doneto validate the method of building the damper force-velocity model. Anadjustable damper that is used on semi-active suspension has beendesigned.Secondly, by building a seven-degree-freedom vehicle control modelof the automotive semi-active suspensions is studied in this paper.,the thesis discussed the characteristics of suspension system. With thestate space approach of the modern control theory ,the controllabilityand observe ability of vehicle suspension system is discussed, and drewa conclusion that vehicle suspension system is discussed, and drew aconclusion that vehicle suspension system is controllable andobservable.At last, the thesis discussed the fuzzy logic control ofsemi-active suspension abstractly and summarized 81 fuzzy logic rulesof suspension control, when looking the root square mean of differentfrequency component of the acceleration of bodywork vibration as theinput of fuzzy logic control unit and the stepper number of stepper motoras the out put of fuzzy logic control unit.And the fuzzy control is then adopted in the research of semi-activesuspensions. First, a regulatory table of basic fuzzy control is given,and a basic fuzzy controller is designed, and a system of basic fuzzycontrol is established. Second, a regulatory table of fuzzy controlperformance determination and a fuzzy controller are also designed.What's more, a system of fuzzy control are given. Finally, the fuzzycontrol systems are used to control the model of the automotivesemi-actives suspensions simulated by MATLAB simulation respectively.During the design of the fuzzy controller, the fuzzy control algorithmis modified and simplified to diminish the complication of the algorithm.The theoretical analyses and MATLAB simulation results show that thedynamic performance of the fuzzy control semi-active suspension isbetter than that of basic fuzzy control semi-active suspension, and muchbetter than that of the passive suspension.