Study On Finite Time Control Strategy Of Valve Control Hydraulic Servo System

With the rapid development of space industry,the electro-hydraulic system has higher accuracy and faster response;but the nonlinearity-phenomenon impact on system characteristics becomes more obvious correspondingly.As a result,it's necessary to establish an accurate nonlinear model of valve-controlled hydraulic system as well as to design a controlling method,which can apply to hydraulic system and realize fast accurate tracking.In this paper,the valve-controlled hydraulic system is taken as the research object,and a system nonlinear mathematical model is established.Based on the sliding mode control method,the finite-time position tracking controller is designed by constructing dynamic terminal function and global dynamic sliding surface.The MATLAB and AMESim simulation are carried out to verify the control method.The experimental platform of the hydraulic system is built.The specific research works areas follows:Firstly,an accurate mathematical model of the valve-controlled hydraulic system is established.The valve-controlled hydraulic system can be divided into three parts:the servo valve,the hydraulic cylinder and the external load.Based on the theoretical knowledge of fluid mechanics,three essential equations are established,which contains the equation of servo valve nonlinearity flow,the flow continuity equation of two working chambers of hydraulic cylinder,the force balance equation of piston rod and external load of hydraulic cylinder.Afterwards the mathematical model of the valve-controlled hydraulic system is caried out.Secondly a finite-time control method is designed under the controlling requirements of limited time.A global dynamic sliding mode eontroller is designed and a solution method of n order dynamic terminal function is given by selecting dynamic switching surface.The simulation is verified in MATLAB/Simulink.Besides,the Co-simulation study on the finite time control method is carried out.This paper uses AMESim hydraulic simulation software and MATLAB/Simulink simulation software to carry out co-simulation,and to further verify the controlling effect in limited time.At last,the control method is experimentally studied.Based on the above theoretical research and actual parameters of hydraulic system,the mechanical testbed of valve-controlled hydraulic system is built,as well as the software and hardware system of measure-control system are constructed.The effectiveness of the finite-time position controlling method is verified by actual engineer experiment.