Making a robot perform to spec under challenging conditions

Robotic machining of relatively small features on large components potentially offers an opportunity to reduce capital expenditure in various industries. A barrier to this is the inability of robotic machine tools to machine to the tolerances of conventional equipment. This project proposed and tested an algorithm to compensate for robotic machining inaccuracies measured in the part during the machining process.

The algorithm was designed to be executed in a two stage process. Initially, programmed cutting coordinates are corrected according to inspection data that encompasses machining error to create a penultimate measured cut. Finally, the finishing program coordinates are compensated to correct under-cuts during the initial measured cut stage.

Conceptual tests using simulated measurement data gave confidence that the proposed approach works well. In experiments, a key area for further R&D effort was found to be associated with error measurement process optimisation. This gave direction to improve measurement system performance to enable the metrology assistance approach proposed to be implemented and therefore the economic benefits of “process-to-part” robotic machining to be realised.

This work was published in Measurement: Journal of the International Measurement Confederation in 2016. For more information please contact us or see the full article:

Development and testing of an error compensation algorithm for photogrammetry assisted robotic machining