Extrinsic calibration method for 3D scanning system with four coplanar laser profilers

Abstract

3D scanning is a crucial step to ensuring the machining quality of the workpiece and is an essential part of intelligent manufacturing. However, existing scanning systems usually have only one profiler, which must be combined with a dynamic tracking system to achieve a complete scan of a workpiece. This scanning method has low efficiency and complicated path planning for ring-shaped workpieces. Therefore, in this article, an efficient and high-accuracy 3D scanning system composed of a linear translation stage and four uniformly distributed laser profilers is built, and its extrinsic calibration method is studied. At first, based on the working parameters and spatial layout of multiple profilers, a stereoscopic calibrator composed of three non-collinear target balls (TBs) is designed. Then, a multi-profiler data fusion method is proposed, which utilizes a linear encoder to trigger the four profilers synchronously. Finally, by simultaneously using all data from the multiple profilers and the spherical constraint of each TB, all extrinsic parameters are accurately calibrated at the same time. Experimental results show that the average probing size error of the TB with a 38.1 mm diameter is stable at about 0.007 mm, and its extended uncertainty is about 0.100 mm (k = 2). In addition, standard cylinders and bend tubes are scanned. The results show that the proposed method can meet the high-accuracy calibration requirements of the tube-bending deformation detection system.