Vision measuring technology for the position degree of a hole group

Abstract

The hole is one of the most important geometric elements in mechanical parts. The center distance of a hole group measurement method based on machine vision is proposed for solving the influence of perspective distortion and improving the applicability of vision systems. In the method, the plane equation of the measured plane is obtained by the line structured light vision technology, and the process is free from the constraints of the calibration plate. In order to eliminate the effect of projection distortion on the measurement accuracy, a local coordinate system is established on the plane of the measured hole group, the hole diameter, and the center distance of the hole group, which could be calculated by the local coordinates of the hole edge points. In the experiment, the flange is taken as the measured object, the distances between the holes on the flange are obtained by the method proposed in this paper, and the measurement results compared with the data are obtained by a coordinate measuring machine (CMM). The experimental results show that the average measurement error of center distance is 0.0739 mm, and the standard deviation is 0.0489 mm.

Noncontact measurement of rectangular splines shaft based on line-structured light

“…The direction cosines of each axis in the local coordinate system can be solved based on the spatial relationship between the corresponding axes in the local and camera coordinate systems. The transformation matrix and method for converting the local coordinate system to the camera coordinate system can be determined based on the transformation relationship and solution method used in spatial borehole group measurements, as proposed by Liu et al [27]. Since the origins of the two coordinate systems established in this paper coincide with each other, the translation matrix is a zero matrix.…”