Research on Algorithm of Pointer Instrument Recognition and Reading Based on the Location of the Rotation Center of the Pointer

Aiming at the inspection requirements of substation equipment, a pointer instrument recognition and reading algorithm based on the pointer rotation center position was designed. Firstly, the original ORB feature matching algorithm is improved to realize the recognition and searching of the instrument. A similar feature triangle method is proposed to determine the rotation center of the pointer by matching feature points. According to the central coordinate, the gesture of the PTZ is controlled through the serial port instruction to make the target instrument positioned to the center of the image; the pointer instrument is read by the method of Hough transform. The results show that the accuracy and real-time performance of similar feature triangle method for identifying the center of rotation of the pointer is increased by 88.88% and 88.03%, respectively, compared with the gravity method. And the mean deviation of the meter reading is 0.011 MPa, which is better than that without positioning by the rotation center of the pointer. The error of the instrument reading was reduced by 67.65%. The experimental results show that the pointer rotation center can be extracted rapidly and accurately by the algorithm, and the error of instrument reading is reduced more, and the inspection requirements of the substation equipment can be met better.