Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer

This study investigated the physical implications and design conditions for a nominal inertia matrix for operational space perturbation observer-based control, including operational space disturbance observer-based control and operational space time delay control. Previous reports indicated that usi...

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Main Authors: Sang Hyun Park, Seongil Hwang, Murim Kim, Sang Hoon Kang
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/10858163/
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author Sang Hyun Park
Seongil Hwang
Murim Kim
Sang Hoon Kang
author_facet Sang Hyun Park
Seongil Hwang
Murim Kim
Sang Hoon Kang
author_sort Sang Hyun Park
collection DOAJ
description This study investigated the physical implications and design conditions for a nominal inertia matrix for operational space perturbation observer-based control, including operational space disturbance observer-based control and operational space time delay control. Previous reports indicated that using a constant diagonal nominal inertia matrix deteriorated control performance and led to instability. However, the underlying physical implications of the constant diagonal nominal inertia matrix and its effect on control performance remained unclear for decades. We identified that the main problem arises from the loss of information on the robot’s kinematics. The loss resulted in a joint space representation of the operational space nominal inertia matrix that is neither positive-definite nor uniformly bounded, with its principal inertia becoming zero at singular configurations. Moreover, uncompensated residual coupled dynamics of the robot are significantly amplified by the inverse of a principal inertia approaching zero, disturbing the closed-loop dynamics and causing dynamic coupling and even instability. In light of these findings, physics-based conditions for selecting the operational space nominal inertia matrix were proposed: operational space nominal inertia must be positive-definite, and its joint space representation must be positive-definite and uniformly bounded from below. Extensive experiments using a 2 degree-of-freedom robot verified these physical implications and physics-based conditions. Our findings are expected to provide insights into the role and selection criteria of the operational space nominal inertia matrix, thereby promoting the practical application of the operational space perturbation observer in various robot applications requiring robust, efficient, and straightforward control.
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spelling doaj-art-221b34cda059424388246e5fad5df30b2025-02-07T00:01:44ZengIEEEIEEE Access2169-35362025-01-0113222702228210.1109/ACCESS.2025.353679910858163Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation ObserverSang Hyun Park0https://orcid.org/0000-0003-3647-4462Seongil Hwang1https://orcid.org/0009-0004-2289-9923Murim Kim2https://orcid.org/0000-0001-5420-9705Sang Hoon Kang3https://orcid.org/0000-0002-7907-9772Department of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South KoreaDepartment of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South KoreaKorea Institute of Robotics and Technology Convergence (KIRO), Pohang-si, South KoreaDepartment of Mechanical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South KoreaThis study investigated the physical implications and design conditions for a nominal inertia matrix for operational space perturbation observer-based control, including operational space disturbance observer-based control and operational space time delay control. Previous reports indicated that using a constant diagonal nominal inertia matrix deteriorated control performance and led to instability. However, the underlying physical implications of the constant diagonal nominal inertia matrix and its effect on control performance remained unclear for decades. We identified that the main problem arises from the loss of information on the robot’s kinematics. The loss resulted in a joint space representation of the operational space nominal inertia matrix that is neither positive-definite nor uniformly bounded, with its principal inertia becoming zero at singular configurations. Moreover, uncompensated residual coupled dynamics of the robot are significantly amplified by the inverse of a principal inertia approaching zero, disturbing the closed-loop dynamics and causing dynamic coupling and even instability. In light of these findings, physics-based conditions for selecting the operational space nominal inertia matrix were proposed: operational space nominal inertia must be positive-definite, and its joint space representation must be positive-definite and uniformly bounded from below. Extensive experiments using a 2 degree-of-freedom robot verified these physical implications and physics-based conditions. Our findings are expected to provide insights into the role and selection criteria of the operational space nominal inertia matrix, thereby promoting the practical application of the operational space perturbation observer in various robot applications requiring robust, efficient, and straightforward control.https://ieeexplore.ieee.org/document/10858163/Time delay controldisturbance observerperturbation observeroperational spacenominal inertia matrix
spellingShingle Sang Hyun Park
Seongil Hwang
Murim Kim
Sang Hoon Kang
Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
IEEE Access
Time delay control
disturbance observer
perturbation observer
operational space
nominal inertia matrix
title Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
title_full Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
title_fullStr Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
title_full_unstemmed Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
title_short Physical Implications and Physics-Based Design Conditions of Nominal Inertia Matrix for Operational Space Perturbation Observer
title_sort physical implications and physics based design conditions of nominal inertia matrix for operational space perturbation observer
topic Time delay control
disturbance observer
perturbation observer
operational space
nominal inertia matrix
url https://ieeexplore.ieee.org/document/10858163/
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AT murimkim physicalimplicationsandphysicsbaseddesignconditionsofnominalinertiamatrixforoperationalspaceperturbationobserver
AT sanghoonkang physicalimplicationsandphysicsbaseddesignconditionsofnominalinertiamatrixforoperationalspaceperturbationobserver