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Separable Control Lyapunov Functions with Application to Prostheses

Gehlhar, Rachel and Ames, Aaron D. (2021) Separable Control Lyapunov Functions with Application to Prostheses. IEEE Control Systems Letters, 5 (2). pp. 559-564. ISSN 2475-1456. doi:10.1109/lcsys.2020.3004181.

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This letter extends bipedal trajectory tracking methods to prostheses to enable construction of a class of model-dependent prosthesis controllers using locally available sensor information. The rapidly exponentially stabilizing control Lyapunov functions (RES-CLFs) developed for bipedal robots guarantee stability of the hybrid zero dynamics in the presence of impacts that occur in walking. These methods cannot be directly applied to prostheses because of the unknown human dynamics. We overcome this challenge with two RES-CLFs, one for the prosthesis subsystem and another for the remaining human system. Further, we outline a method to construct these RES-CLFs for this type of separable system by first constructing separable CLFs for partially feedback linearizable systems. This letter develops a class of separable subsystem controllers that rely only on local information but provide formal guarantees of stability for the full hybrid system with zero dynamics.

Item Type:Article
Related URLs:
URLURL TypeDescription
Gehlhar, Rachel0000-0002-4838-8839
Ames, Aaron D.0000-0003-0848-3177
Additional Information:© 2020 IEEE. Manuscript received March 17, 2020; revised June 3, 2020; accepted June 4, 2020. Date of publication June 22, 2020; date of current version July 7, 2020. This work was supported in part by the National Science Foundation Graduate Research Fellowship under Grant DGE-1745301, in part by NSF NRI under Grant 1724464, and in part by the RoAMS Initiative.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
Robotic Assisted Mobility Science (RoAMS) initiativeUNSPECIFIED
Subject Keywords:Lyapunov methods, nonlinear systems, prosthetics
Issue or Number:2
Record Number:CaltechAUTHORS:20200625-151814604
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Official Citation:R. Gehlhar and A. D. Ames, "Separable Control Lyapunov Functions With Application to Prostheses," in IEEE Control Systems Letters, vol. 5, no. 2, pp. 559-564, April 2021, doi: 10.1109/LCSYS.2020.3004181
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104065
Deposited By: George Porter
Deposited On:26 Jun 2020 14:29
Last Modified:16 Nov 2021 18:28

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