An Optimal Dynamic Control Method for Robots with Virtual Links

Woolfrey, J; Liu, D

An Optimal Dynamic Control Method for Robots with Virtual Links

Woolfrey, J Liu, D

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Publisher:: Institute of Electrical and Electronics Engineers (IEEE)
Publication Type:: Conference Proceeding
Citation:: IEEE International Conference on Intelligent Robots and Systems, 2022, 2022-October, pp. 12843-12848
Issue Date:: 2022-01-01

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Field	Value	Language
dc.contributor.author	Woolfrey, J
dc.contributor.author	Liu, D https://orcid.org/0000-0002-1581-5582
dc.date	2022-10-23
dc.date.accessioned	2023-03-09T05:02:23Z
dc.date.available	2023-03-09T05:02:23Z
dc.date.issued	2022-01-01
dc.identifier.citation	IEEE International Conference on Intelligent Robots and Systems, 2022, 2022-October, pp. 12843-12848
dc.identifier.isbn	9781665479271
dc.identifier.issn	2153-0858
dc.identifier.issn	2153-0866
dc.identifier.uri	http://hdl.handle.net/10453/166802
dc.description.abstract	Virtual links and virtual joints can be appended to the kinematic chain of a robot arm to assist in modelling and control of certain tasks. Activities such as spray painting, sand blasting, or scanning with a laser or camera can be enhanced by modelling the fluid stream, light beam, or field of view using a virtual link. Virtual joints can be used to allow movement in semi-redundant degrees of freedom of the task space. This can can be exploited to optimize the control of the real robot. A prudent choice is to minimize the effort required by the manipulator to execute the task. This often requires the inversion of the inertia matrix. However, virtual links have no inertia so the inverse does not exist. This paper first explores methods of adding virtual mass or modifying the inertia matrix to allow inversion and the consequences. Then an optimal control problem is proposed that minimizes kinetic energy in the real manipulator and maximizes use of the virtual joints. In doing so, we only need the real inertia matrix which is always invertible. The method is validated in a case study for high pressure water blasting. It is shown to reduce the dynamic torque norm compared to a minimum velocity controller.
dc.language	en
dc.publisher	Institute of Electrical and Electronics Engineers (IEEE)
dc.relation.ispartof	IEEE International Conference on Intelligent Robots and Systems
dc.relation.ispartof	2022 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
dc.relation.isbasedon	10.1109/IROS47612.2022.9982273
dc.rights	info:eu-repo/semantics/closedAccess
dc.title	An Optimal Dynamic Control Method for Robots with Virtual Links
dc.type	Conference Proceeding
utslib.citation.volume	2022-October
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Strength - RI - Robotics Institute
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Mechanical and Mechatronic Engineering
utslib.copyright.status	closed_access	*
dc.date.updated	2023-03-09T05:02:21Z
pubs.finish-date	2022-10-27
pubs.publication-status	Published
pubs.start-date	2022-10-23
pubs.volume	2022-October

Abstract:

Virtual links and virtual joints can be appended to the kinematic chain of a robot arm to assist in modelling and control of certain tasks. Activities such as spray painting, sand blasting, or scanning with a laser or camera can be enhanced by modelling the fluid stream, light beam, or field of view using a virtual link. Virtual joints can be used to allow movement in semi-redundant degrees of freedom of the task space. This can can be exploited to optimize the control of the real robot. A prudent choice is to minimize the effort required by the manipulator to execute the task. This often requires the inversion of the inertia matrix. However, virtual links have no inertia so the inverse does not exist. This paper first explores methods of adding virtual mass or modifying the inertia matrix to allow inversion and the consequences. Then an optimal control problem is proposed that minimizes kinetic energy in the real manipulator and maximizes use of the virtual joints. In doing so, we only need the real inertia matrix which is always invertible. The method is validated in a case study for high pressure water blasting. It is shown to reduce the dynamic torque norm compared to a minimum velocity controller.

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http://hdl.handle.net/10453/166802