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Calibration of an Elastic Humanoid Upper Body and Efficient Compensation for Motion Planning

Tenhumberg, Johannes and Bäuml, Berthold (2021) Calibration of an Elastic Humanoid Upper Body and Efficient Compensation for Motion Planning. In: 20th IEEE-RAS International Conference on Humanoid Robots, Humanoids 2020. IEEE. IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids), 2021-07-19 - 2021-07-21, Munich, Germany. doi: 10.1109/HUMANOIDS47582.2021.9555793. ISBN 978-172819372-4. ISSN 2164-0572.

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Official URL: https://ieeexplore.ieee.org/abstract/document/9555793


High absolute accuracy is an essential prerequisite for a humanoid robot to autonomously and robustly perform manipulation tasks while avoiding obstacles. We present for the first time a kinematic model for a humanoid upper body incorporating joint and transversal elasticities. These elasticities lead to significant deformations due to the robot's own weight, and the resulting model is implicitly defined via a torque equilibrium. We successfully calibrate this model for DLR's humanoid Agile Justin, including all Denavit-Hartenberg parameters and elasticities. The calibration is formulated as a combined least-squares problem with priors and based on measurements of the end effector positions of both arms via an external tracking system. The absolute position error is massively reduced from 21mm to 3.1mm on average in the whole workspace. Using this complex and implicit kinematic model in motion planning is challenging. We show that for optimization-based path planning, integrating the iterative solution of the implicit model into the optimization loop leads to an elegant and highly efficient solution. For mildly elastic robots like Agile Justin, there is no performance impact, and even for a simulated highly flexible robot with 20 times higher elasticities, the runtime increases by only 30%.

Item URL in elib:https://elib.dlr.de/146302/
Document Type:Conference or Workshop Item (Poster)
Title:Calibration of an Elastic Humanoid Upper Body and Efficient Compensation for Motion Planning
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Tenhumberg, JohannesUNSPECIFIEDhttps://orcid.org/0000-0002-5090-1259UNSPECIFIED
Bäuml, BertholdUNSPECIFIEDhttps://orcid.org/0000-0002-4545-4765UNSPECIFIED
Date:20 July 2021
Journal or Publication Title:20th IEEE-RAS International Conference on Humanoid Robots, Humanoids 2020
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Keywords:robotics, calibration, motion planning
Event Title:IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids)
Event Location:Munich, Germany
Event Type:international Conference
Event Start Date:19 July 2021
Event End Date:21 July 2021
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Robotics
DLR - Research area:Raumfahrt
DLR - Program:R RO - Robotics
DLR - Research theme (Project):R - Autonomous learning robots [RO]
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Robotics and Mechatronics (since 2013)
Deposited By: Tenhumberg, Johannes
Deposited On:08 Dec 2021 14:25
Last Modified:24 Apr 2024 20:45

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