Data Acquisition System for Calibration of Handheld Digital Multimeters through Digital Image Processing

Abstract

The purpose of the project was to develop an automatic system for the acquisition and recognition of measurements taken by handheld digital multimeters through the use of images; this was proposed in order to improve their calibration process in the magnitudes of direct and alternating current, direct and alternating voltage, and electrical resistance. Thus, a system was developed to automatically capture, process, and recognize the values associated with multimeter readings in its calibration process, divided into three stages: The first stage consisted of creating a database with information of the multimeter models to be calibrated, the standard instrument (evaluating the feasibility of using it in the process), and the calibration points. In the second stage, an algorithm was developed to identify and classify the values displayed on the under-test multimeter. In the third stage, the process of uncertainty estimation, reporting, and evaluation of the validity of the results was carried out. From this last subprocess, it was determined that the capture and uncertainty estimation system is adequate to perform the calibration of the evaluated handheld digital multimeters.