Design And Research Of The Calibration System For Rotating-element Current Meter

Rotating-element current meter is the essential instrunent to obtain hydrological data of rivers,lakes and other,it plays an important role in the hydrological career development in our country.Because current meter working environment is bad,precision accuracy will decline and can't meet the standard provisions of the state when use after a period of time,so the current meter requires verification and calibration on a regular basis.Current meter verification is dependent on the current meter calibration system,calibration system of precision directly affects the accuracy of the current meter verification results.This topic is based on the above background,the ultimate goal is to design an advanced current meter calibration system which has high accuracy,high reliability,high stability,high degree of automation.In order to achieve the above-mentioned purpose,based on the insight into development status at home and abroad about the current meter calibration system,this paper is determined to choose static sink calibration system;Based on the analysis of the structure and design requirements of the calibration system of rotating-element current meter,the main factors influencing the accuracy of the calibration system are summarized.Based on these,the author designed the whole structure of the calibration system of rotating-element current meter system,including the design and equipment selection of the basic unit,the communication mode,the drive unit,the speed regulation unit,steering unit and the control room.Because the speed accuracy of the motor on the current meter calibration car is one of the important factors to determine the accuracy of the whole system,so in this article,the calibration car speed problem is researched in detail,a new speed control method of motor servo control system based on fuzzy neural network and PID control is proposed.After completion of the fuzzy neural network control system and controller design,through the Simulink simulation and comparing with the traditional PID control to prove superiority of the fuzzy neural network combined with PID control method in the motor speed of current meter calibration car.Through the analysis of the current meter signal,it is found that the interference of water resistance,mechanical dithering,signal isolation and peak signal is particularly large,which seriously interfere with the accuracy of signal acquisition.On the above several main disturbances,different solutions are proposed in this paper.Finally,the signal conditioning circuit is designed from both hardware and software,which improves the accuracy of the verification system.By analyzing the characteristic curve of the Rotating-element current meter and the data processing method,the least squares method is adopted to process the data,this method accuracy satisfies the requirement of system,the fitting effect is good.The third order least-squares fitting mathematical model was used to fit the low-speed segment of the characteristic curve;The first-order linear least-squares fitting mathematical model was used to fit the high-speed section of the characteristic curve of the velocity meter.