The Research Of Reading Recognition System For Nonlinear Analog Measuring Instruments Based On Embedded Linux

Analog measurement instruments, because of their simple structure and convenient operation, apply widely in industry, such as electric-power, petrolum, chemical, automation, and so on. But they almost operate manually in the course of getting readings and being examined and repaired termly, which sometimes operations give or take a lot of trouble. By combining machine vision and digital image processing technology, it deals with the showing images, and obtains dial information and pointer's reading, so as to realize automatic calibration, which could advance rate, and reduce spending.This paper presents an automatic recognition system;it simulates the reading process of man: firstly read the scale value, and then estimate the pointer decimal value. For familiar scale dials, especially nonlinear scale, bring forward a new recognition way, by using the corresponding relation of scale division, scale interval and scale value that could recognizing the reading of lienear and nonlinear dials.This paper also presents one way of falling together scale and angle to mend the old means of recognizing pointer angle. For one thing, it gets the scale exact angle which is valid and round the pointer by the known scale trait, for another calculates the evaluation pointer, and its error has been between two scale marks. Compared with the measure of angle ratio relation, it enhances the precision of result by means of fixing attention on near scales of the pointer, and reaches expected effect. As a typical example, this paper also introduces detailedly about recognizition of Ohmmeter and voltmeter scale, and reach expected effect by Matlab emulateing the scale arithmetic.It brings forward a design based on embedded system for the system, embedded linux as its operating system, and also Qt/Embedded as its GUI tools. And it also uses USB camera to fulfill image data acquisition. Based on embedded linux system for automatic recognition of analog measuring instruments, it could reduce cost, improve applicability, and so on.The means of recognizing reading from image, and design of embedded system,could make many instruments interlink, including no interface mechanical and electric ones, which haven't normal interfaces. All make for integrating various instruments, to improve the automation of detection system, so it will be widely used in the future.