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Experimental Closed-Loop Excitation of Nonlinear Normal Modes on an Elastic Industrial Robot

Bjelonic, Filip and Sachtler, Arne and Della Santina, Cosimo and Albu-Schäffer, Alin (2022) Experimental Closed-Loop Excitation of Nonlinear Normal Modes on an Elastic Industrial Robot. IEEE Robotics and Automation Letters. IEEE - Institute of Electrical and Electronics Engineers. doi: 10.1109/LRA.2022.3141156. ISSN 2377-3766.

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Official URL: https://ieeexplore.ieee.org/document/9674820

Abstract

Adding elastic elements to the mechanical structure should enable robots to perform efficient oscillatory tasks. Still, even characterizing natural oscillations in nonlinear systems is a challenge in itself, which nonlinear modal theory promises to solve. Therein eigenmanifolds generalize eigenspaces to mechanical systems with non-Euclidean metrics and thus characterize families of oscillations that are autonomous evolutions of the robot. Eigenmanifolds likewise provide a framework for deriving feedback controllers to excite and sustain these oscillations. Nevertheless, these results have been so far essentially theoretical. They have been applied on relatively low dimensional systems and almost exclusively in simulation. We aim to bridge the theory to the real-world gap with the present work and show that we can excite nonlinear modes in complex systems. To this end, we propose control strategies that can simultaneously stabilize numerically evaluated eigenmanifolds and sustain oscillations in the presence of dissipation. We then focus on the KUKA iiwa with simulated parallel springs as an example of the highly nonlinear and articulated system. We calculate all the nonlinear modes of the system, and we use the proposed strategies to excite the associated natural oscillations.

Item URL in elib:https://elib.dlr.de/148128/
Document Type:Article
Title:Experimental Closed-Loop Excitation of Nonlinear Normal Modes on an Elastic Industrial Robot
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Bjelonic, Filipfilip.bjelonic (at) gmail.comhttps://orcid.org/0000-0002-4890-3132
Sachtler, ArneArne.Sachtler (at) dlr.dehttps://orcid.org/0000-0003-4974-4134
Della Santina, CosimoC.DellaSantina (at) tudelft.nlhttps://orcid.org/0000-0003-1067-1134
Albu-Schäffer, AlinAlin.Albu-Schaeffer (at) dlr.dehttps://orcid.org/0000-0001-5343-9074
Date:7 January 2022
Journal or Publication Title:IEEE Robotics and Automation Letters
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1109/LRA.2022.3141156
Editors:
EditorsEmailEditor's ORCID iD
Asfour, TamimInstitute for Anthropomatics and RoboticsUNSPECIFIED
Publisher:IEEE - Institute of Electrical and Electronics Engineers
ISSN:2377-3766
Status:Published
Keywords:Motion Control; Dynamics; Modeling, Control, and Learning for Soft Robots
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 - Walking robot/locomotion [RO], R - Robot Dynamics & Simulation [RO], R - Mechatronics [RO]
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Robotics and Mechatronics (since 2013)
Deposited By: Sachtler, Arne
Deposited On:11 Jan 2022 15:37
Last Modified:11 Jan 2022 15:37

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