Sliding Mode Control Study For Hydraulic System Based On Improved LuGre Model

The electro-hydraulic control system realizes the timely and accurate tracking of the given amount of the system through the hydraulic actuator.The electro-hydraulic control system is easy to realize functions such as long-distance operation,wide-range speed regulation,and high output power.It has the advantages of large power-to-volume ratio,fast response speed,and strong anti-load rigidity,making it widely adaptable in modern industrial power systems.However,the rapid development of industrial technology has put forward higher requirements for the control accuracy of electro-hydraulic control systems.The electro-hydraulic control system is a complex nonlinear system with uncertain nonlinear problems such as modeling uncertainty,parameter time-variation,nonlinear friction and external interference.The existence of friction characteristics seriously restricts the control of the electro-hydraulic control system Increased accuracy.Therefore,it is of great research significance to improve the control accuracy of the electro-hydraulic control system through friction compensation.Aiming at the complex nonlinear problem of hydraulic system,this subject analyzes the valve-controlled cylinder system model and uses the system state equation obtained by neural network modeling as the controlled object to study the sliding mode control algorithm.The main research contents of this topic are as follows:The LuGre friction model that can accurately express the friction characteristics is used to perform friction compensation on the system.The amount of bristle deformation in the LuGre model is an unmeasured state variable,and this variable needs to be estimated by designing state estimator.Based on the existing two-state estimator and the core idea of sliding mode control,this paper designs a two-state sliding mode estimator to estimate the state of the bristle deformation information.An adaptive sliding mode controller is designed.By constructing the Lyapunov function,proving that the improved state estimation system is still progressively stable.Integrating the integral term into the sliding mode controller,integrating the differential terms into the design of the two-state sliding mode estimator and adaptive rate,and designing an adaptive rate improvement integral sliding mode control scheme based on the two-state sliding mode estimator.The introduction of the integral term can accelerate the speed of the system to reach the sliding mode,which is helpful to eliminate the steady-state error under uncertain conditions.The introduction of the differential term can accelerate the approach speed of the adaptation rate,so that the estimated value of the parameter can quickly reach its true value.The incomplete differential backstepping sliding mode controller is combined with the two-state sliding mode estimator to design an incomplete differential backstepping sliding mode control scheme based on the two-state sliding mode estimator.Analysis proves the stability of the system.According to the simulation experiment results,the effectiveness of the control scheme proposed in this paper is analyzed.This subject uses the electro-hydraulic control comprehensive experimental platform to verify the above control schemes,analyze the experimental results,and compare the control performance of different control schemes.