Calibration Techniques for Industrial Mobile Manipulators: Theoretical configurations and Best practices

At the moment autonomous industrial mobile manipulation (AIMM) is a subject of major focus in development and research environments, as it is a technology with significant potential. However, we are experiencing a lack in calibration techniques, in order to obtain industrially acceptable localization and manipulation tolerances. In this paper two calibration methods (high-precision and high-speed) are proposed, with the purpose of defining sufficient localization of a mobile manipulator in relation to a workstation. Initially the techniques are presented in their theoretical forms, and subsequently the focus is on verification (experiments) and practical use (applications). The high-precision calibration is based on the Tsai hand-eye calibration in a modified and automated configuration, while the high-speed calibration is based on a combination of laser triangulation and image processing. Experiments and applications, based on the proposed techniques, have been carried out with a full-scale mobile manipulator ("Little Helper" from the Department of Production, Aalborg University). The obtained tolerances and processing times are promising - high-precision; [±0.1 mm, ± 0.1deg, 60 seconds] and high-speed; [± 1.0 mm, ± 1.0deg, 10 seconds] - in relation to industrial integration of mobile manipulators.