Research On Cascade Control Strategy Of Active Suspension System

Active suspension can regulate the active control force automatically according to the road environment and vehicle operation condition,which can intervenes the vibration process of suspension and greatly improve the riding comfort and handling stability.Real-time control of the suspension system actuator output force to achieve active suspension system performance according to the vehicle itself parameters and road input parameters is the core and difficult part of research.The active suspension models most in research use always simplify the actuator to control force,which do not consider the characteristics of the actuator.So there is a certain gap to the actual system.In addition,the traditional simple control algorithm cannot fully meet the vehicle on the active suspension system performance needs.This paper starts from the establishment of a more perfect active suspension model and the proposed cascade control algorithm.The control strategy of active suspension system is studied deeply and the main research contents are:Firstly,active suspension control system strategy related papers and research materials were studied and analyzed and analyzes the problems and shortcomings of the control strategy currently applied to the active suspension system.Secondly,according to cascade control principle of combining a variety of control strategies,the optimal control and sliding mode control of the cascade active suspension control strategy is proposed.And the advantages of cascade control strategy in active suspension control system are analyzed.Thirdly,according to the characteristics of the active suspension state space equation,the system is divided into internal and external ring structure.At the base of study the optimum control theory and sliding model control theory,after analyzing the advantages of the optimal control method and the sliding mode control method,the paper puts forward the optimal control and sliding model control cascade control strategy.Then,after rationally simplifying the active vehicle suspension model,the active suspension dynamic equation including the active suspension hydraulic actuator is established and converted into the state space equation.According to the characteristics of the nonlinear term in the state space equation of the active suspension system,the system is divided into inner and outer ring structures.The inner and outer rings of the system are controlled by linear quadratic optimal control strategy and sliding mode control strategy respectively.The optimal control and sliding mode control cascade control strategy of active suspension is formed and set up in Simulink Road input model,hydraulic active suspension model and cascade control strategy model.Finally,the active suspension and its control system of passenger car are simulated and analyzed on the random input pavement and simple bumpy road defined in the paper.The simulation results show that compared with the traditional fuzzy PID control strategy,the control effect of cascade control strategy is better,which take the performance indicators of the active suspension into account and can get the best control effect.This paper analyzes the dynamic characteristics of the hydraulic actuator in the active suspension system and puts forward the cascade control strategy on the basis of establishing mathematical model of hydraulic actuator active suspension system and proposing optimal and sliding mode cascade control strategy.Compared with the traditional active suspension fuzzy PID control strategy,the optimal control and the sliding mode control cascade control strategy cascade control strategy have better control effect;the research results of this paper have certain practical value for improving the performance of vehicle active suspension control strategy.