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dc.contributor.author
Özparpucu, Mehmet Can
dc.contributor.supervisor
Buchli, Jonas
dc.contributor.supervisor
Ott, Christian
dc.contributor.supervisor
Dullerud, Geir E.
dc.date.accessioned
2018-10-22T14:27:57Z
dc.date.available
2018-10-22T10:34:28Z
dc.date.available
2018-10-22T14:27:57Z
dc.date.issued
2018
dc.identifier.uri
http://hdl.handle.net/20.500.11850/297795
dc.identifier.doi
10.3929/ethz-b-000297795
dc.description.abstract
In this thesis, we investigate the problem of maximizing the link velocity of elastic joints using velocity-sourced elastic actuators. More specifically, focusing on joints with nonlinear series elastic actuators we derive motor control strategies such that the link velocity is maximized at a given time instant when the joint is initially at rest. Furthermore, we provide a physical interpretation for the derived strategies by exploiting their time optimality. The interpretation reveals the dependence of these strategies on periods of mass-spring systems which in turn explains how nonlinear torque-deflection profiles influence the maximal link velocity. In order to clearly illustrate this influence, we analyse in detail three different elastic joints with softening, linear and hardening springs. In particular, we compare their maximal link velocities as well as the corresponding control strategies and elaborate on the observed differences. Our theoretical results are experimentally validated on the DLR Floating Spring Joint where link velocities at least more than three times the maximally applied motor velocity are attained in less than a second. Several extensions are also provided which reveal the influence of damping and stiffness actuation on optimal control strategies. Finally, we give a proof of Pontryagin's Minimum Principle, the main theorem used in the thesis, by exploiting the properties of transition maps. Assuming an additional degree in the smoothness of the system dynamics and the cost functional, this leads to an extension of the principle, namely the Second Order Minimum Principle.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.subject
Optimal control
en_US
dc.subject
Nonlinear Springs
en_US
dc.subject
Elastic Joints
en_US
dc.subject
Series elastic actuators
en_US
dc.subject
Variable Stiffness Actuators
en_US
dc.subject
Variable Damping Actuators
en_US
dc.subject
Pontryagin's Minimum Principle
en_US
dc.subject
Second Order Minimum Principle
en_US
dc.title
Optimal Control Strategies for Maximizing the Link Velocity of Elastic Joints with Nonlinear Impedance
en_US
dc.type
Doctoral Thesis
ethz.size
231 p.
en_US
ethz.identifier.diss
25266
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02130 - Dep. Maschinenbau und Verfahrenstechnik / Dep. of Mechanical and Process Eng.::02620 - Inst. f. Robotik u. Intelligente Systeme / Inst. Robotics and Intelligent Systems::03965 - Buchli, Jonas (SNF-Professur) (ehem.) / Buchli, Jonas (SNF-Professur) (former)
en_US
ethz.date.deposited
2018-10-22T10:34:29Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Embargoed
en_US
ethz.date.embargoend
2021-10-22
ethz.rosetta.installDate
2018-10-22T14:28:02Z
ethz.rosetta.lastUpdated
2018-10-22T14:28:02Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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