Research On Pointer Type Instrument Value Identification Based On Machine Vision

In the modern society’s manufacture and life, the pointer type instrument is widely used in various fields as measurement instruments, they have low price, a huge number, and various kinds. The pointer type instrument has some characteristics that other instruments do not have, and because of some special industry’s specific needs, so the pointer type instrument won’t be die. In recent years, the machine vision technology and digital image processing technology developing rapidly, various testing system that based on the machine vision technology gradually moving towards to the practical phase in the industrial field. Researching make use of the machine vision technology to recognize the pointer type instrument’s value is of great social significance and application value.On this topic, the object that should be identified is a pointer type voltmeter, first, using the machine vision technology to acquire the pointer type instrument’s dial image, and then using the digital image processing technology to preprocess the dial image, then extract and recognize the pointer, and finally, the pointer type instrument’s value will be read automatically. These results not only contribute to the solution of artificial reading process’s problems, such as large amount work, easy to make mistakes and so on, but also can be used to upgraded the old backward production line and systems, that conform to the trend of modern information society. On this topic, the main work that I did and results including:1.Design this machine vision value recognition system’s overall plan, including hardware platform and software platform;2.Analyze the working principle of image collection system of the pointer type instrument value recognition system, research the influence of the equipment and devices of the image acquisition system on the instrument value identification, including light source, lighting way, the analysis and choosing of a camera, for example, choosing a LED light source, front lighting diffuse reflection;3.Using digital image processing technology to preprocess the pointer type instrument’s dial image, including selecting the appropriate and necessary image pretreatment process and algorithm, such as using the histogram equalization technology to enhance the image, median filtering method for removing noise, adaptive threshold value method for the dial image’s binarization;4.Researching the general method for confirming the line parameters of the pointer, using sent shadow method to extract the pointer’s characteristic, then using the least square method to fit the pointer’s straight line, finding out the two pointer straight lines’intersection angle, then we can get the pointer’s value; And did some extensive research, put forward a new method to determine the direction of the pointer. Through the comparison between the whole journey that the pointer sliding in the circular arc and the perimeter of the whole arc, then concludes the relationship between the deflection angle of the objective pointer to the zero pointer and the intersection angle of the two straight pointer line, so as to determine the direction of the pointer.On the development platform of Visual C++, programming to realize the algorithm and process, and doing some actual experiments to recognize the pointer type instrument’s value. Through the analysis of experimental results, we know that the algorithm is correct, the method is feasible, and has a certain application value.