Determining robot contour accuracies on non-standard geometries using imaging techniques

Abstract:
Determining contour accuracies of robotic CNC machine tools can be a laborious task usually involving elaborate and expensive equipment accompanied by time-consuming set-up procedures. Even when relying on external measurement sensors, the contour accuracy can only be studied on predetermined geometry rarely comparable to the CNC machining job at hand. Furthermore, some measurement systems will only give plausible results on strictly standardized geometries or contours. We present a practical, cost-efficient and easy to set up device giving accurate and easily interpretable results on robot contour accuracy. The device does not require external components, it is not limited to standard contours of specific dimensions and introduces – to the best of our knowledge – a new image processing technique to create a visual representation of the desired contour, the actual contour, contour deviation and actual feed rate. Our technique enables us to systematically evaluate series of CNC application tests of different dynamic parameters, monitor wear of gear boxes and investigate advanced control schemes and path pre-calculation strategies in laboratory and workshop scenarios.