Research On Nonlinear Modeling And Control Strategy Of Vehicle Active Hydraulic Suspension System

The car is a common tool in people's daily life and production.With the development of social economy and the improvement of people's living standard,people have more and more strict requirements on automobile performance.Suspension,as an important part of a car,plays an important role in the vehicle's driving safety,operational stability,and ride comfort.Active suspension consumes external energy to provide active force for the car.Compared with traditional passive suspension and semi-active suspension,it can adapt to more complicated road conditions,and has gradually become the focus of research in the field of suspension.This paper analyzed the nonlinear hydraulic active suspension system,focusing on how to improve the ride comfort under the premise of considering all kinds of vehicle constraints.The main research contents of this article are as follows:Firstly,a 1/2 vehicle suspension model is established considering the uncertain parameters of the system,the nonlinear characteristics of the double lever hydraulic actuator and the possible disturbance of the system.The model with hydraulic actuator has higher order,a sliding mode adaptive controller is designed to solve this problem,the controller combines the sliding mode and the adaptive algorithm,which can improve the driving comfort of the vehicle,estimate the uncertain parameters of the system online and suppress the external disturbance.Secondly,in view of the large volume occupied by the double lever hydraulic actuator in the limited space of the automobile chassis,considering the single lever hydraulic actuator which is widely used in the automobile field and occupies a small volume,a 1/2 suspension model is established.In order to solve the problem that the vertical velocity of tire and the pressure in the hydraulic cylinder are not easy to obtain,a sliding mode adaptive controller with extended state observer is designed,which makes the controller closer to the practical application and has a good guiding role for the engineering practice.Finally,the stability of the controlled system is proved,and the sinusoidal signal isselected as the road input for simulation.The results show that the controller designed in this paper can ensure the safety and the limited suspension travel in the driving process of the vehicle,and the comfort is significantly improved compared with the passive suspension.When the system has strong external disturbance signal,the control strategy in this paper shows a stronger advantage than the traditional backstepping adaptive control strategy.