Research On Optimization Of Magnetorheological Damper And The Control Of Semi-active Suspension System

With the development of society,people have higher and higher requirements for the performance of cars.Suspension system is an important part of automobile.To a certain extent,the driving performance of vehicle depends on the performance of suspension system.Due to the limitation of its own structure,the traditional passive suspension can no longer meet the requirement,and the intelligent suspension has become an inevitable trend in the development of modern automobiles.With the advantages of simple structure,short response time,large damping force and continuously adjustable,the semi-active suspension based on MR damper has become a research hotspot.Based on the optimization design of MR damper,this paper studies the control strategy of semi-active suspension which based on MR damper.The main works are as follow:(1)The characteristics of three different types of suspension are compared.The research status of magnetorheological damper at home and abroad and the control strategy of semi-active suspension are summarized.The flow characteristics of MR fluid and the working principle of MR shock absorber are described.The working mode and mechanical model of MR damper are analyzed,and a MR damper is designed on this basis.(2)Multi objective genetic algorithm(MOGA)is used to optimize the structural parameters of the preliminary designed piston with the maximum damping force and dynamic adjustable coefficient as the objectives.The physical vapor deposition(PVD)technology is used to deposit AlCrN coating on the piston rod to improve the corrosion resistance of the piston rod.The magnetic field distribution of the optimized piston is analyzed by finite element method.According to the optimized parameters,the prototype of MR damper is manufactured and the dynamometer test is carried out on the damper bench.(3)A 1/4 vehicle semi-active suspension model and its system state equation are established.In order to improve the simulation accuracy,the dynamic equation of semi-active suspension which is discretized,and the evaluation indexes of suspension performance are determined.Based on the filtered white noise,the B-level and C-level random road input models are established respectively,and the forward mechanical model of MR damper is established on the basis of Bouc-Wen model.According to the mechanical formula of Bingham model,the reverse model of MR damper is deduced.(4)Based on PID control and fuzzy control methods,a fuzzy PID controller and a current control module are designed according to the characteristics of MR semi-active suspension.According to the reverse model,the control current is obtained by the expected damping force,so as to control the output damping force of MR damper and realize the control of semi-active suspension.The system simulation model of each module is built in Matlab/Simulink,and the simulation analysis is carried out on B-level and C-level road respectively.The simulation results verify the effectiveness of the fuzzy-PID control algorithm designed in this paper.