The Research Of Automatic Calibration System For Pressure Gauges With Pointers Based On Computer Vision

The pressure gauges with pointers is a common measuring instruments, which widely used in every industrial field, To ensure the reliability, stability of the pressure gauges, the pressure gauges need periodic detection before the use and in use. The automatic recognition technology of the pressure gauges with pointers is very important for antomatic calibration devics, and it is also the key technology of the automatic calibration system.This article adopted the technique of computer vision and digital image processing technology to realize the automatic reading recognition of the pressure gauges with pointers, and research an automatic calibration system for pressure gauges with pointers based on computer vision. This system consists of pressure gauges test management system and pressure gauges indication automatic interpretation systems two parts, which can be used in pressure gauges wirh pointers on a regular test in oilfield, and reduce labor intensity of inspectors, and have good social values. This paper carried out the following research areas:1、Research the automatic calibration system for pressure gauges with pointers:Formulated the overall design of the calibration system consisting of related hardware and software,the hardware includes the selection and design of pressure gauges calibration platform、industrial camera、light source、sliding rails、ect.The designed pressure gauges calibration platform can achieve automatic pressure control when calibrate the pressure gauges,that is the pressure required to quickly and automatically given and steady,without the need for human intervention。The software includes the pressure gauges dial image acquisition program, pressure gauge pointer automatic reading recognition program,the pressure gauges with pointers automatic reading recognition program.2、Research the method to improve the reading accuracy of the pressure gauges with pointers:Use DOME light to improve the quality of dial images, and use canny operator in edge detection for images, and use Otsu approach to turn a color image into a binary image, and use Hough transform approach to extract the pointer, and use maximum connected domain approach to extract the dial scale, finally through Hough transform to determine the slope k of the line pointer, thereby calculate the pointer reading of pressure gauges, though the application of these methods can improve the accuracy of readings.3、Build an experimental platform to achieve the automatic calibration for pressure gauges:The stability and accuracy of the test system have been proved through a lot of experiments, the experimental data showed that automatic reading accuracy meets the certification requirements, and do some useful work for achieving the final automatic calibration of the pressure gauges.