Calibration method of spatial transformations between the non-orthogonal two-axis turntable and its mounted camera

Abstract

In order to expand the field of view and measuremenst range, the camera is often mounted on a two-axis turntable to perform various visual tasks. And the calibration of the position and attitude relationship between the mounted camera and the two-axis turntable is a prerequisite for visual measurement. The turntable is considered an ideal orthogonal two-axis turntable in conventional methods. However, the rotation axes of the actual two-axis turntable may be neither vertical nor intersecting, and the optical center of the mounted camera is not always located in the rotation center of the turntable even for orthogonal two-axis turntables. The quite difference between the actual physical model of the two-axis turntable and the ideal model can cause large errors. Therefore, what we believe to be a novel position and attitude calibration method between a non-orthogonal two-axis turntable and the mounted camera is proposed. This method describes the spatial hetero-planar lines relationship between the azimuth axis and pitch axis of the turntable accurately. By the geometric invariant characteristics of the mounted camera in motion, the axes of turntable are recovered and the base coordinate system is established, and the position and attitude of the camera are calibrated. Simulation and experiments verify the correctness and effectiveness of our proposed method.