The Model Bullding, Simulation And Application Research Of Valve Control Electro-hydraulic Servo System With Pipeline

The electro-hydraulic servo system involve in the merits of both electricity and hydraulic pressure. It not only has the facility of electric system's checking, rectifing and error signal magnifying, but also has the advantages of hydraulic system's high response and load of resistance, high power-weight ratio of hydraulic element, controlled variable closed loop control, etc. Those make it to be the best system in servo control field. It has been applicated to many fields of both national economy and military industry, especially used on the occasions that need large weighted loading and high-response speeds.With electro-hydraulic servo control technique developing,the dynamic characteristics of system have become a significant criterion of system performance. Pipeline connect different components of hydraulic system, its dynamic performance affects hydraulic system greatly. Though shorter pipeline can improve system's performance, long one will change system dynamic characteristics greatly.The flow pulsation of pump in system and hydraulic shock caused by frequent start and stop of hydraulic valve make flow pattern of liquid in pipe complex. Therefore, establishing exact pipeline model and studying the effect of pipeline on system's dynamic characteristics become a very important topic increasingly.This thesis concentrate on studing and solving these problems, the pipeline model is established, then, putting it into the real coiler step control system and making simulation and test study.In chapter 1, the background of diesis are represented .The author elaborate the influence of pipeline on system performance, and the application of the electro-hydraulic servo system in coiler steps control system and overview the contribution of researches indomain and oversea on the fluid pipeline dynamics, the pipeline model and coiler steps eledtric-hydraulic servo system control aspect. After these discussions, the main objective of this research project is showed at the end of this chapter.In chapter 2, the author introduces modeling theory of hydraulic system, establishs mathematical model of every component in valve control electro-hydraulic servo system and carries on simulation analysis to the system."In order to solve the problem of low-response in system without adjustment, in chapter 3, the author adjusts the system by the methods of PID control, acceleration-velocity feedback and pressure and dynamic pressure feedback.In chapter 4, the pipeline distribute parameter model and lumped model are established, due to the traditional lumped parameter model only involve in laminar flow pattern but not turbulents. In this article, the laminar and turbulence combination model is established, then vertified. To study effect of pipeline on system dynamic characteristic, a valve control system's mathematic model is created, then make simulation study withpipeline model in it.In chapter 5, the system model established has been applied to the coiler step control system, mathematic model of coiler actuator are set up. The simulation study of real system is made. The response Characteristics of asymmetric cylinder controlled by symmetric and asymmetric valve is contrasted. The frequency-domain performance of coiler hydraulic system is analysised.In capter 6, Aiming at the control system of step device of Lai Yang steel factory's cotter, analog experiment bench is established to make experiment study, then the comparison between test result and simulation result is made.Chapter 7 is the final chapter of this thesis, and all the research contents are summarized.