Research On Automatic Calibration Algorithm For Dial Instrument

Analog measurement instruments, because of their simple structure, convenient operation, high stability, reasonable price and so on, are applied widely in the industry. However, in the use process according to the Verification Regulation of Analog Measurement Instruments, they need calibration. The traditional method of calibration leads to the accuracy is not high, low efficiency problem.Digital image processing technology (DIT) has been widely applied in recent years in various fields. If DIT applies to the calibration of measurement instruments, it will overcome the traditional method default and improve the efficiency of the calibration and automaton process.In this paper, according to method of the pointer of dial instrument is derived by the power source, using stepper machines and grating system as a standard source of input systems, through the image acquisition system to obtain image information of the analog measurement instrument, automatic identify the instrument reading and judge whether the instrument qualified. It focuses on the identification algorithm of the automatic meter reading. First of all, through the image acquisition system to obtain dial image, then identified the pointer and scales after image segmentation, and finally determine the reading. Niblack algorithm using image segmentation of the instrument can be better solution to the problem of uneven illumination image. This paper introduces several traditional algorithm of identification of pointer and scales and carries out an algorithm to identify the scales through making the circle to a rectangular. This algotithm is simple and easy, and could be incomplete dial scale perfect line. Experiments have proved that the feasibility of the algorithms, and automation of performance, accuracy. For automatic calibration of measurement instrument provides a practical program.