Characteristic Analysis Of Asymmetric Valve Controlled Asymmetric Cylinder Digital Hydraulic Cylinder

This paper chooses asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder as the research subject.The main contents of this study are as follows:A complex transfer function mathematical model of asymmetrical valvecontrolled asymmetrical cylinder digital hydraulic cylinder considering contact stiffness and damping of ball screw and feedback nut thread pair is established.Based on this complex transfer function mathematical model,the control block diagram of asymmetrical valve-controlled asymmetrical cylinder digital hydraulic cylinder is established,and a series of reasonable control block diagrams are simplified,and the specifications are obtained.Simplified control block diagram of asymmetric valvecontrolled asymmetric cylinder digital hydraulic cylinder.Simulink is used to verify the correctness of the simplification process.Based on the complex control block diagram model of asymmetric valvecontrolled asymmetric cylinder,the stability,response characteristics,stiffness characteristics and accuracy of the system are analyzed theoretically.The open-loop transfer function of the system is obtained,the open-loop Bode diagram of the system is drawn,the stability of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder is analyzed,the stability conditions of the system are obtained,and the factors that affect the stability of the system in asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder are known.The response characteristics of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder are analyzed.It is concluded that the frequency bandwidth of the system is approximately equal to the open-loop amplification coefficient of the system.Therefore,according to the mathematical expression of the open-loop amplification coefficient of the system,the influencing factors of the frequency bandwidth of the system can be understood.The stiffness characteristics of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder are analyzed,the static control block diagram of the system is drawn,the closed-loop transfer function of the system's external load force is obtained,the closed-loop static stiffness of the system is deduced,and according to the mathematical expression of the closed-loop static stiffness,the influence of variables on the system and the law of influence are understood.The accuracy of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder is analyzed.The tracking errors of three typical input signals,step signal,slope signal and equal acceleration signal,are derived respectively,and the tracking errors of the system in steady state are calculated.According to the definition of load errors,the mathematical expressions of load errors are deduced,and the influencing factors of load errors are revealed.Based on the AMESim non-linear model of asymmetric valve-controlled asymmetric cylinder,the theoretical analysis results of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder control characteristics based on complex mathematical model are simulated and verified.First,the AMESim model of asymmetric valve-controlled asymmetric cylinder digital hydraulic cylinder is established,and then the stability,response,stiffness and stiffness of the system are successively analyzed.Corresponding simulation validation is made for the accuracy.The simulation results fully prove the theoretical analysis of the control characteristics.