Calibration of a circular structured light measurement system based on a multi-diameter calibrator

Abstract To solve the measurement problems of the inner shape of large-scale workpieces, such as excavators with movable arms, this paper proposes an inner shape measurement method based on circular structured light. First, the center of the circular laser stripe is extracted based on a modified Steger method. Second, a multi-diameter concentric calibration gauge design is used to calibrate the optical plane of the proposed system and address the problem of the optical plane deviation and motion error in the 1D linear stage of the traditional calibration process. Finally, the experiments are conducted. The corresponding experimental results demonstrate that the proposed measurement method facilitates a fast calibration of the camera and an efficient extraction of the center of the light stripe, resulting in a relative error of less than 0.012%. The measurement method can be further applied to deep-hole workpieces, such as steel tubes and natural gas tube lines, among others.