CAM-based planning, programming and execution of large-scale machining operations by a robot-mounted gantry system

This paper examines issues related to planning, programming and execution of machining operations by a robot in the context of machining large parts with complex geometries by a gantry-mounted robotic system. Parts were created from surface data in a CAD/CAM environment. The same environment was used to generate tool paths using a conventional machine tool approach. These paths were converted to robot trajectories and validated using mathematical kinematic models of the robotic system. Validation was performed according to various criteria related to process performance. Associated robot programs were then automatically generated. The manufacturing cell was progressively integrated according to requirements resulting from iterative process characterization. A metrology-based calibration procedure was designed that considerably improved the system's positioning precision. A custom user interface for online process monitoring was created as well as online cell program management capabilities to accommodate the large quantity of trajectory information. The system went from conceptual, to prototype-level to full production mode, thereby covering several Manufacturing Readiness Levels (MRL). The various strategies used in planning the process and programming the system demonstrate the viability of CAM-based approach for robot machining path generation without resorting to the use of OLP packages for validation of program generation. This could create a shift in the dependency on robotic specialists, allowing machine tool experts to carry about the programming of robot machining cells using the conventional machine tool approach.