Control Method Of Vehicle Magneto-Rheological Semi-active Suspension With Continuously Adjustable Damping

As the force transmitting device between vehicle body and wheel,vehicle suspension is used to buffer pavement impact and damp vibration caused by road uneven,and it is the key to ensure riding comfort of passengers and driving safety of the vehicle.Vehicle semi-active suspension utilizes magneto-rheological(MR)control technique to adjust damp continuously in real time,reduce vehicle vibration and improve riding comfort and handling stability,in addition,it has advantages such as simple structure,strong controllability,low energy consumption and environmental protection etc.Taking vehicle MR suspension as research object,this paper focuses on the research of MR damper inverse model,vehicle suspension controller,vehicle suspension status detection,vehicle coordinated control strategy in semi-active suspension control system by theoretical analysis,experiment and numerical simulation.Aiming at the phenomenon of strong nonlinearity and hysteresis characteristics of the MR damper,the positive kinetic model of Bouc-Wen phenomenon model is established by experimental research and model parameter identification.The input current and displacement are used to determine the damping force.In order to realize closed-loop control of semi-active suspension control system,the BP neural network inverse model of MR damper optimized by genetic algorithm(GA)is established to get corresponding control current from expected damping force,which solves the control problem of actuator.According to the influence of road change on vehicle vibration,the time domain models of two typical road excitations(continuous vibration input and impact input)are established.The simulation models of 2-DOF 1/4-vehicle,4-DOF 1/2-vehicle and 7-DOF whole vehicle MR suspension are established for different research purposes.Aiming at the disadvantage of over-reliance on expert experience in fuzzy PID control method for vehicle semi-active suspension,genetic algorithm is used to optimize the fuzzy control rules.The results of simulation tests of 2-DOF 1/4-vehicle semi-active suspension under different working conditions verify the effectiveness of the proposed composite control strategy in reducing the vertical vibration of the vehicle.The simulation test of 4 DOF 1/2 vehicle semi-active suspension further validates its vibration reduction effect on vertical vibration,pitch(or roll)motion and their coupling vibrationIn order to obtain the state value of vehicle suspension parameter,a kind of vehicle suspension state monitoring system is designed by rational arrangement of sensors.The state equation and observation equation are established according to the state value of vehicle suspension and the observed values of sensors.The performance parameters of vehicle semi-active suspension,such as dynamic deflection,tire dynamic load and vehicle vertical,pitch and roll are estimated by extended Kalman filter estimation algorithm.The simulation results show that the proposed algorithm can realize real-time and effective estimation of vehicle suspension state parameters.In order to improve the control of body vibration in three directions and their coupling vibrations,as well as to realize neutral steering,the coordinated control strategy with force coordinator and steering control strategy are designed to distribute the expected adjusting force in three directions to four MR dampers.The test results and analysis of continuous vibration input and impact input are shown:Compared with semi-active suspension without force coordinator,vehicle MR semi-active suspension system with whole vehicle coordinated control strategy has better riding comfort and handling stability.Under the same road level,the improvement effect of semi-active suspension performance index is more obvious as the speed increase;but the suspension performance deteriorates with the increase of vehicle speed,which is not conducive to the smooth running of the vehicle,so it is still necessary to control the speed reasonably.Under Different road levels at the same speed,the change of road level has certain effect on suspension performance index,while compared with the influence of speed,its effect is small.