Calibration method for visual-guided laser tracker measurement system based on the Cayley transformation

As for using just one laser tracker to measure several points, a new method of visual-guided laser tracking was presented. A camera was set on the top of the laser tracker, and rotates around the laser tracker's Z axis. When measuring, the camera rotated a single revolution with the laser tracker, and captured the positions of all the laser interferometers. The coordinates of the positions in the camera frame can be converted to the laser tracker frame, and then the laser designator projected a laser sheet to the laser interferometers. A planar round hole target was used, and the center of the holes were measured simultaneously by the camera and the laser tracker. The corresponding coordinates in the two frames which were processed using mean method becomes the corresponding vectors in the two frames. The translation of the two group vectors is the rotation matrix of the two frames. Using Cayley transformation, the rotation matrix of the two frames can be calculated, and then the whole relationship between the two frames can be obtained by using any two corresponding coordinates. The advances of the algorithm are the solving process is simple and the results are stable. Simulation is shown that, when the number of the target placing is more than 50, the influence of the image noise is stable, and the measuring error is less than 1 mm. The proposed method is simple, has strong stability, and has very high practical value.