The Application And Research Of Parallel Control With Two Valves For The Electro-hydraulic Position Control System

Double valve parallel control system discussed in the paper refers to using two electric-hydraulic servo valves together to control the system, through a appropriate control strategy,in order to improve the overall performance.This paper is aimed at raising the minimum steady speed and ensuring the speed range is sufficient, by using two servo valves with different rated flow to realize the performance of expensive foreign servo valve achieved, so as to reduce the cost of electro-hydraulic position control system.This paper can be divided into two aspects,on the one hand proving double valve parallel control system’s of necessity and feasibility in theory, on the other hand searching for a suitable control strategy to make both valves working in the best performance, so that the whole system can obtain the best control effect.The paper starts with the theoretical analysis and mathematical modeling of electro-hydraulic position control system.Then it expands to the background project and gives the reason of the system’s failure performanc in low speed.On the basis of ignoring some minor factors,the paper focus on the parameter of threshold and build a model for it which was introduced to the whole model to observe the changing caused by threshold. All of this proves that double valve parallel control make sence to improve the performance of system.Whether a suitable control method were chose means a lot to the performance of double valve parallel control system.To pursue a faster dynamic response and running more smoothly when two valves are switched,fuzzy algorithm were used in the design of two controllers.To perform better than the MOOG valves will be a important point.One controller means to adjust the open-loop gain and the other one control the proportion of flow output from the bigger valve.By comparison,the overall performance of system controlled by the fuzzy controller are better than the other control strategy referred in the ability of adaptable,steady,and smoothly switching. At last,a fixed gain controller was designed to keep the total gain of system a constant,which was simple in structure and make the system more steady.To get a more realistic simulation results of the conclusion we get before, a co-simulation model was built with AMEsim and Simulink.AMEsim is uesd to build the hydraulic system,while Simulink is used to build the control system.At last,an experiment has been done to test and verify the theoretical analysis and simulations discussed in the paper in a certain extent with the existing experimental equipment.Besides,from the result and analysis of the experiment,some useful advices have been put forward for the designing or using of double valve parral control system.