Research On The Control Strategy Of Semi-avtive Suspension Based On Magnetorheological Dampers

Magnetorheological damper has simple structure,low energy consumption,and high reliability.Due to those above advantages,it has very broad application prospects in the field of automobile suspension.Most of the vehicles with MR dampers on market are based on traditional control strategy,although the control effect is tolerable,modern nonlinear control algorithms and Intelligent control algorithms require less accuracy of control object model,and also have stronger adaptability of nonlinear and time-varying characteristics as for a complicated system like magneto-rheological semi-active suspension,In recent years more and more domestic scholars began to apply modern control algorithms and intelligent control algorithms in the study of suspension control strategy.For these purposes,this paper has mainly done the following job:The paper introduces the generation method of random road signal and established the dynamic model of semi-active vehicle suspension,and then discusses the transmission characteristics of vehicle comfort,suspension dynamic deflection and tire dynamic load performance,and the impact of the suspension spring stiffness and damping coefficient to the suspension performance.On this basis,the article analyzes the liquid composition and rheological mechanism of magneto-rheological fluid damper,and then indicates the working principle of magnetorheological damper,and also discussed the external characteristics of magneto-rheological damper through numerical simulation.At the same time,based on the parametric model of magneto-rheological damper,a nonlinear semi-active suspension model based on magnetorheological damper is established,and the expressions of control current and damping force are obtained.The discussion of these problems provides a theoretical basis and direction for the study of the semi-active suspension control strategy.On the basis of those discussion,the paper starts with the sky-hook strategy and introduced the ground-hook control strategy to compensate the deficiency of unsprung mass control,and finally obtained the hybrid control strategy of semi-active suspension by adding system state judgment.In order to determine the influence of the damping coefficient and the balance coefficient to the performance of the suspension,the optimal objective functions indicating different aspects of the suspension are established.Based on the objective function,the simulation model of semi-active suspension based on hybrid control strategy and passive suspension are established.The paper then discusses the influence of damping coefficient and balance coefficient on performance objective functions through numerical analysis,and finally obtained the range of the parameters.Based on the obtained adjustable range of the parameters,the semi-active suspension expert PID controller is designed.Finally,the simulation experiments are carried out under several different road situations.The simulation results show that the proposed control strategy effectively suppressed the vibration of sprung mass and unsprung mass.Based on the analysis of nonlinear characteristics of magneto-rheological suspension of semi-active suspension,three different continuously variable nonlinear controller structures and algorithms are designed.For the insufficient stability consideration of ordinary adaptive control,an adaptive model-free control method of semi-active suspension is realized and a dynamic current limiter is also designed based on the dynamic characteristics and constraints of MR damper.At the same time,the adaptive fuzzy PID controller with dual imputs and single output structure is applied to the nonlinear system based on the predictive control objectives and fuzzy control strategy.The simulation results of the semi-active suspensions are compared and analyzed by the three control methods.The results show that the suspension under adaptive fuzzy-PID control and model-free adaptive control both have lower impulse response and lower vibration intensity than passive suspension system.Adaptive fuzzy-PID control has better performance than fuzzy-PD control and model-free adaptive control.