Lishchuk R. Computer system for testing of pointer-and-scale measuring instruments

The dissertation's subject matter is the development of a new computer system for testing of pointer-and-scale measuring instruments in static and dynamic modes. The basic requirements to existing computer systems for testing of pointer-and-scale measuring instruments are analyzed and formulated. As a result it is defined that the existing computer systems for testing of pointer-and-scale measuring instruments don't work in dynamic mode. Besides, the number of instruments that are tested simultaneously is limited, on the one hand, by the formation of a test signal, and, on the other hand, by the type of instruments scale and their metrological characteristics. Therefore, the use of the analyzed computer systems in production is primarily determined by the availability of high-speed image processing algorithms, measurement accuracy, simplicity of hardware components and decision-making time about the quality of the instrument under testing. The ways of implementation of the method of optical reading of the scales of pointer-and-scale measuring instruments are investigated and prerequisites for the formation of a new computer system for testing of pointer-and-scale measuring instruments in static and dynamic modes are created. The structural diagram of a computer system consisting of webcam, test-signal generator and software is suggested. Test-signal generator is built on microcontroller ATmega8. It allows to operate the test signal in static and dynamic modes. The choice of test signal for testing of pointer indicators intended to visualize the measured value of amperage (amperemeters), constant and variable magnitude of voltage (voltmeters) and measured value of resistance (ohmers) is implemented. The software, which consists of the following units: binarization of images, difference of images, filtration of images, skeletonization of images and identification of instrument indices is developed. The proposed software allows to identify readings of the scales of pointer-and-scale measuring instruments in static and dynamic modes. A method of adaptive binarization of images is developed. It is based on an integral representation of the image. With the use of the integral representation of the image a significant reduction of the time of algorithm operating is obtained due to the fact that all the calculation components are saved in an integral matrix and the calculation takes four accesses to the file and three arithmetic operations. The proposed method allows to avoid sharp contrasting lines and to ignore small gradient changes. The flooding method of skeletonization of binary images is improved. It differs from the well-known one by the way of circles generation. Each successive circle is generated on the determined point of center axis of the object. As a result of the execution of algorithm we find points of center axis of the object that can be used to represent skeletal image. The proposed method can consider the expansion (narrowing) and rotational motion of the object. It is resistant to noise on the image. Analytical dependences of identifying the angle of deflection of cursor of the instruments with arc and circular scales are received. The main results of the research have industrial implementation at joint-stock partnership "Uman plant" Megommetr" during acceptance testing.