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Series Elastic Tether Management for Rappelling Rovers

Brown, Travis and Stefanini, Alessandro and Georgiev, Nikola and Sawoniewicz, Jacek and Nesnas, Issa (2018) Series Elastic Tether Management for Rappelling Rovers. In: 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). IEEE , Piscataway, NJ, pp. 2893-2900. ISBN 9781538680940.

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The Axel rappelling rover was designed to enable access to intriguing and important science sites that lie in difficult terrains that are inaccessible to conventional rovers. Extended autonomous rappelling calls for careful control of tether tension, precise management of tether spooling, and some measure of shock tolerance. This paper covers the design and testing of a first-generation tether management system (TMS) for Axel. The system uses a double bull-wheel capstan driven by a low-stiffness series elastic actuator (SEA) to provide tension control and decouple internal spooling tension from external tether tension. A series elastic actuator was chosen for this application to permit closed-loop tether tension control and to provide shock/drop tolerance of the rappelling system both while moving and when the system is inactive with the motors locked. Experiments on the new TMS show that this design performs well in keeping nearly constant spooling tension while rejecting large dynamic disturbances at the output. While the SEA is very effective at maintaining a given tension contribution, the additional effects of friction and the unique mechanical properties of the tether result in substantial errors in the measured output tension. Upcoming field trials will be used to evaluate the effectiveness and sufficiency of this system when integrated in Axel.

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Additional Information:© 2018 IEEE. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The authors would like to thank and acknowledge the following: NASA Marshal Space Flight Center for lending their time and manufacturing expertise to support this project, Andre Pate for providing manufacturing consultation, and Evan Yu for design and fabrication work that significantly contributed to the success of this project.
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Record Number:CaltechAUTHORS:20190201-152505546
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Official Citation:T. Brown, A. Stefanini, J. Sawoniewicz, I. Nesnas and N. Georgiev, "Series Elastic Tether Management for Rappelling Rovers," 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Madrid, Spain, 2018, pp. 2893-2900. doi: 10.1109/IROS.2018.8594134
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92591
Deposited By: George Porter
Deposited On:01 Feb 2019 23:44
Last Modified:16 Nov 2021 03:51

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