Print Email Facebook Twitter Experimental Closed-Loop Excitation of Nonlinear Normal Modes on an Elastic Industrial Robot Title Experimental Closed-Loop Excitation of Nonlinear Normal Modes on an Elastic Industrial Robot Author Bjelonic, Filip (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Sachtler, Arne (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); Technische Universität München) Albu-Schaffer, Alin (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); Technische Universität München) Della Santina, C. (TU Delft Learning & Autonomous Control; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)) Date 2022 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. Subject and Learning for Soft RobotsControlDynamicsModelingMotion Control To reference this document use: http://resolver.tudelft.nl/uuid:9d2c2539-973e-4db9-969a-ff3ebcf86086 DOI https://doi.org/10.1109/LRA.2022.3141156 ISSN 2377-3766 Source IEEE Robotics and Automation Letters, 7 (2), 1689-1696 Bibliographical note Accepted Author Manuscript Part of collection Institutional Repository Document type journal article Rights © 2022 Filip Bjelonic, Arne Sachtler, Alin Albu-Schaffer, C. Della Santina Files PDF Experimental_Closed_Loop_ ... _Robot.pdf 6.95 MB Close viewer /islandora/object/uuid:9d2c2539-973e-4db9-969a-ff3ebcf86086/datastream/OBJ/view