Research On Semi-active Suspension Based On Air Spring And Mr Damper

Vehicle vibration problems will not only affect ride comfort,but also cause body failures and reduce vehicle life.In order to make the vehicle exhibit excellent vibration isolation performance under different levels of road surface,this paper has conducted research on air springs and magnetorheological dampers,two control strategies for suspension stiffness and damping are proposed,and the vibration isolation effects of the two are compared through simulation analysis.The specific research contents are as follows:Corresponding pavement excitation models were constructed for different levels of pavement,based on the solution of the suspension dynamic model,the state equation of the semi-active suspension was established.Through simulation analysis,the influence law of suspension damping coefficient,stiffness coefficient,spring loaded mass on suspension performance index under different pavement excitation conditions was obtained.Based on the MRD mechanical characteristic data obtained by the experiment,the parameters in each model were identified and fitted using genetic algorithm and least square method,and then the Bingham model,Tanh model and improved Tanh model of MRD were established.Two MRD inverse dynamic models were established based on the Bingham model and the improved Tanh model.Through comparison,it is found that the forward and reverse dynamic model based on the improved Tanh model has advantages in model accuracy,parameter identification difficulty and reversibility.The structure and principle of the vehicle’s air suspension were studied.The mechanism of the air spring was analyzed by using the ideal gas state equation and the law of thermodynamics.The quantitative relationship between spring output force and gas temperature,internal pressure of air bag,rate of change of effective area with height and other parameters is obtained,and a mathematical model of air spring is established based on the above research.Two types of suspension damping coefficient controllers were established by using the canopy damping control strategy and the fuzzy control strategy respectively.And a suspension stiffness controller is established based on fuzzy control principle.Two suspension stiffness and damping joint control strategies are designed by combining suspension stiffness controller and damping controller.Through simulation analysis,it is found that the semi-active suspension using the skyhook fuzzy control strategy has the best optimization effect on impact excitation and random road excitation signals.