Abstract
Large-scale surfaces are prevalent in advanced manufacturing industries, and 3D profilometry of these surfaces plays a pivotal role for quality control. This paper proposes a novel and flexible large-scale 3D scanning system assembled by combining a robot, a binocular structured light scanner and a laser tracker. The measurement principle and system construction of the integrated system are introduced. A mathematical model is established for the global data fusion. Subsequently, a robust method is introduced for the establishment of the end coordinate system. As for hand-eye calibration, the calibration ball is observed by the scanner and the laser tracker simultaneously. With this data, the hand-eye relationship is solved, and then an algorithm is built to get the transformation matrix between the end coordinate system and the world coordinate system. A validation experiment is designed to verify the proposed algorithms. Firstly, a hand-eye calibration experiment is implemented and the computation of the transformation matrix is done. Then a car body rear is measured 22 times in order to verify the global data fusion algorithm. The 3D shape of the rear is reconstructed successfully. To evaluate the precision of the proposed method, a metric tool is built and the results are presented.
Highlights
Large-scale thin wall and surface components are widespread in modern high-end manufacturing industries, especially in the automotive, shipbuilding, astronautical and aeronautical industry
The integrated Model robotic system incorporates an industrial robot with six degrees of freedom (DOF), a laser tracker, a digital system fringe projecting (DFP)
With the DFP scanner, By combining the area scanning structured light equipment, the laser tracker and the robot, 3D shape information of the object will be acquired at one robot position
Summary
Large-scale thin wall and surface components are widespread in modern high-end manufacturing industries, especially in the automotive, shipbuilding, astronautical and aeronautical industry. In some researches, a turntable surrounding the robot is introduced to extend the metrology range of the robot system [11,12] Because it combines robot’s flexibility and accuracy of visual profilometry, it is promising for online inspection of large-scale parts. Compared to the laser scanning method, structured light profilometry [17,18,19,20,21] can acquire the data on a surface for each measurement. Thanks to the area scanning property, it has a better time performance For all these advantages, the structured light scanning method will be promising if it is used in large-scale metrology. As for the hand-eye calibration, different from the traditional method, by observing the target ball using the scanner and the end coordinate system, the transformation matrix is computed.
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