Numerical calibration of laser line scanning system with multiple sensors for inspecting cross-section profiles

摘要

Line structured light sensors (LSLSs) have gained more and more applications in industry. An interested profile can be easily obtained through the analysis of laser-object intersection stripe. But one sensor is inadequate to get a closed cross-section profile due to the obstacle of the laser light. Thus, multiple LSLSs were integrated as a whole for profile inspection and a numerical calibration method was also proposed. Firstly, the laser planes from all laser projectors were adjusted to coincide with the target plane by adjusting the fixtures of the laser projector. For each sensor, origin of the world coordinate system (WCS) was fixed at the center of a corner calibration dot with its X and Y axis coincide with the row and column direction of target dots. Each sensor camera captured one image of the same target. The relationship between the pixel coordinate system (PCS) and the WCS was established using an interpolation method via the world coordinates of target dot centers and their corresponding pixel coordinates. Then the measurement points from all the sensors were transformed into the global WCS, and a closed cross-section profile can be achieved. This proposed method neither need to establish the intrinsic, the extrinsic and the distortion models of the camera, nor need to solve the complex optimization equations to determine the model coefficients. Finally, a workpeice with stairs and a rectangular block were inspected. The comparison with the measuring results from the coordinate measuring machine further validates the high accuracy of the proposed method.