Planar image-space trajectory planning algorithm for contour following in robotic machining

This paper proposes the planar image-space trajectory (PIST) planning algorithm for contour following using computer vision and a force control scheme. The PIST algorithm generates machining trajectories offset to a planar workpiece with an applied force direction so that a force controller can be utilized. The PIST algo-rithm starts with an image of the workpiece, corrects for the perspective of the camera, defines a contour following trajectory in image space, and then transfers the trajectory into the robot's workspace for play-back. A case study is presented where the PIST algorithm is applied to deburring sheet metal parts for validation through experimentation. A comparison is performed between the PIST algorithm and CAD/CAM software using CAD data for path design and a laser scanner for localization. The PIST planner achieved a positional accuracy greater than 1.7 mm compared to the CAM/CAM accuracy of 1.2 mm. An admittance controller successfully accounted for the positional error to achieve satisfactory and equivalent surface finish results for both trajectory planning approaches. The PIST planner is a beneficial alternative for tra-jectory planning as it significantly reduced the setup and process time while adapting to deviations from the design dimensions and manufacturing imperfections.Crown Copyright (c) 2023