Automatic and Self-Contained Calibration of a Multi-Sensorial Humanoid's Upper Body

Oliver Birbach; Berthold Bäuml; Udo Frese

In: Proceedings of the IEEE International Conference on Robotics and Automation. IEEE International Conference on Robotics and Automation (ICRA-12), May 12-18, Saint Paul, MN, USA, Pages 3103-3108, IEEE, 5/2012.


Complex manipulation tasks require an accurate interplay of actuation and sensing. This accuracy can only be achieved by calibrating the relevant components beforehand. Typically calibration procedures are time-consuming and often include subsequent calibration steps, multiple involved persons, and external tools. In this paper we alleviate these issues by auto-calibrating the different sensors of DLRs humanoid Rollin Justin in a single, completely automatic and self-contained procedure, e.g., without calibration plate. By observing a single point feature on each of the robots wrists while moving the robots head, the stereo cameras’ intrinsic and extrinsic parameters are calibrated together with the arms joint elasticities and joint angle offsets. Additionally, we use the head’s motion to calibrate an Inertial Measurement Unit (IMU) extrinsically. Parameters are obtained by formulating the calibration problem as a batch-optimization problem estimating all parameters jointly. A rough initial guess, as is available, e.g., when re-calibrating, is needed for the estimation and to facilitate marker detection. The procedure is validated on a real robot. It reduces the effort considerably allowing rapid (5min movement time), automatic, and accurate calibration by simply “pushing a button”.

Deutsches Forschungszentrum für Künstliche Intelligenz
German Research Center for Artificial Intelligence