Real-time pose correction and registration of complex workpiece in robotic machining considering normal consistency constrains

Efficient and precision model registration of complex workpiece with arbitrary pose is a challenging task that determines the effects of intelligent robotic machining. Aiming at the problems of limited field of view of 3D vision sensors such as surface structured light and the complexity of scanning-splicing-registration algorithm, in this paper a real-time pose correction and registration algorithm of complex workpiece in robotic machining considering normal consistency constrains is proposed. Specifically, the operations on ellipse feature detection and center point extraction are performed based on the arc-support line segment, and then the actual three-dimensional coordinate of the ellipse is obtained by the camera conversion matrix. Furthermore, considering the constrained normal consistency of the center points set of ellipses on the model surface, the pose of the target workpiece is corrected in real-time by the improved ICP registration algorithm. Taking the automotive flywheel shell as a typical application object, the experimental results demonstrate that the registration correction time of the proposed algorithm is 0.5 s, and the registration accuracy can reach 0.35 mm. The repetitive correction time of the algorithm after arbitrarily changing the workpiece pose is less than 1 s, and the positioning accuracy of the guiding robot is less than 1.5 mm. On the premise of satisfying the robotic machining quality requirements, the pose of the complex workpiece model can be corrected in real-time for subsequent robotic machining.