Automatic alignment system based on center point recognition of analog measuring instruments dial

This paper casts the problem of the automatic alignment in analog measuring instruments automatic calibration system via center point recognition of dial using total least squares. Random points on the dial contour are selected to establish set of equations, and the coordinate of center point of dial can be obtained by solving system of equations with total least squares. With the coordinate, the movable supporting point on the support frame can be automatically adjusted in vertical direction to the position where the optical axis of camera has same height with the center point. Then, by using the dial contours as a benchmark, the movable supporting point is automatically adjusted in anterior-posterior direction to make the image collected by camera be filled with the dial as possible. SCM (single-chip microcontroller) is used in the acceleration and deceleration of stepping motor discrete control. The experiment results show that the camera can be adjusted to the expected position by this approach accurately and quickly and the system can achieve a better image collection effect.