Research And Design Of Hydraulic Control System In Industrial Measurement Based On PLC

Industrial measuring instruments are widely used in various fields of industrial production.Many of industrial measurement are closely related to pressure testing.For example,pressure gauge is a kind of industrial measuring instrument that is widely used.The industry standard require that the pressure gauge must be checked before use and during use.Manual verification is a traditional verification method of pointer pressure gauges.However,this verification method has disadvantages such as low verification efficiency,large work intensity,visual error,large artifical factors,and poor traceability.With the rapid development of automatic control technology,pressure gauge automatic verification technology came into being.As the pressure control system of the pressure gauge automatic verification system,based on the special requirements of its verification procedures,its control speed and control accuracy are important indicators for evaluating the merits of the pressure control system.This paper comes from an oil field technology monitoring center "the pressure gauge bulk intelligent verification device improvement" project,aiming at the problems existing in the actual use of the original hydraulic pressure control system,such as(1)High pressure control pressure instability(especially when the pressure is over 40MPa);(2)Control pressure response time is too long,the test efficiency is low.The main task of this paper is to study and improve the hydraulic control system.This paper is based on the PLC controller design improved hydraulic control system,mainly including hardware design and system control software design The hardware part mainly includes double hydraulic cylinder design,pre-pressure pump selection and system protection device design,control system selection and design,standard pressure gauge selection and selection of stepper motor and its driver.Based on the problem of unstable control of high pressure in a single hydraulic cylinder control system,a control system based on double hydraulic cylinders was designed.The newly-built small hydraulic cylinder was used to fine-adjust the pressure during high pressure control,which overcomes the problem of unstable high pressure control.The software part is programmed using PLC programming language.Logic control is written in ladder language,and calculation is written in structured text language.The combination of the two languages completes the programming process.In terms of control algorithms,based on the currently used segmented PID control strategy,a gray prediction algorithm and a fuzzy algorithm are added,namely a gray prediction segmented fuzzy PID algorithm.Using the predictive and compensatory characteristics of the grey predictive control algorithm,the system is controlled in real time,and the PID parameters are tuned online using the fuzzy algorithm.Finally increased the pressure control speed.After the hardware and software design is completed,the system must be tested and the system parameters determined during repeated tests.Use KINGVIEW6.55 software as monitoring software,and design the man-machine interface to facilitate system debugging.The experimental results show that the improved system has strong stability,rapid pressure control,zero overshoot,high precision,can meet engineering requirements,and has better pressure control performance than before improvement,achieving the project's intended goals.