A new calibration approach of rotor axes for 3D measurement system

Rotating scan is a common 360-degrees measurement method in 3D measure system which based on line-structure light. In this system, the calibration for rotary axis of the rotary platform is an important section. It will be affecting the measurement results. In known methods, precision and expensive auxiliary instruments are required to ensure that the rotation axis is located in the plane of line-structure light. In this paper, a simple, flexible and real-time calibration method is proposed. Firstly, a plane calibration board with tessellated pattern is placed incline on the rotating stage. Secondly, recoded several pictures of the calibration board while the stage rotating several angles. Thirdly, the parameters of camera (include the intrinsic parameters and the extrinsic parameters, such as rotating matrixes and transform vectors between the local coordinates of these planes and the global coordinate of sensor) can be estimated from these pictures. Then, the global coordinates of these control points were calculated according to these parameters. Finally, the axis parameters of the working stage can be optimized with these control points because the global coordinates of same control point in different position are in circle. This method is proved by experiment, and the root-mean-square error is 0.04mm.