Pointer Instrument Recognition System Based On Digital Image Processing

A variety of instruments used in all aspects of life, from everyday life to aerospace alarm clock have to use the instrument. It is because of the importance of the instrument, the development level of the instrument has become a manifestation of a country’s level of scientific research and technology. Instrument according to different display mode can be divided into two categories:digital display instrument and pointer instrument. Digital instruments through various liquid crystal and nixie light display, while pointer instrument give a specific indication by people observing on the pointer position. Due to the extensive use of the instrument, more and more people pay attention to the intelligent recognition of instrument, especially for the pointer instrument.This system is mainly deal with five different instruments. They are pressure gauge, dial indicator, DYM3 type aneroid instrument, ND10 sound level instrument and DZ-2 vibration instrument. Five kinds of instrument have its own characteristics, so according to their different characteristics there are different treatment methods. Collected all the instruments should go through the image preprocessing. Preprocessing includes image gradation, image enhancement and so on. This paper discusses the characteristics of various preprocessing technology, according to the specific circumstances of the instrument choose the most appropriate treatment methods to improve the recognition accuracy.The innovations of this project are as follows:1. For the presence of the double pointer instrument whose pointer cross-cutting impact we propose a new algorithm, which could accurate reading pointer in the case of mutual interference.2. For the instruments which have both dial pointer and knobs, we propose an efficient algorithm that can read the position of the knob dial readings and determine it based on the relative positional relationship, in order to achieve the reading of the pointer.3. For the instruments which have wide pointer we improve traditional algorithm. Wide pointer in the shape of a narrow triangular, there is a certain angle between the actual position of the pointer and line got by Hough transform, this issue hand this situation, and eliminate the error.4. In response to the identification process targeting difficult circumstances, the subject of innovation in the interface increases the profile and the vertical axis of the instrument, so as to ensure the relative position of the camera with a fixed test instrument.5. In order to adapt to harsh lighting conditions, we add two rows of LED lights to provide lighting around camera, and add a translucent matte board before the LED lights in order to avoiding the formation of dial flare.This topic’s design has very good results in practice, it’s noise immunity is strong, and it can be used in a variety of lighting conditions, the read pointer shows high speed and high accuracy. The principles and algorithms summarized in this paper may have some significance for a variety of intelligent recognition system.