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Series Elastic Tether Management for Rappelling Rovers

Show simple item record Brown, Travis Stefanini, Alessandro Georgiev, Nikola Sawoniewicz, Jacek Nesnas, Issa 2020-05-21T23:56:00Z 2020-05-21T23:56:00Z 2018-10-01
dc.identifier.citation 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems, Madrid, Spain, October 1-5, 2018 en_US
dc.identifier.clearanceno 18-3985
dc.description.abstract 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 tethertension,precisemanagementoftetherspooling,andsome 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. The benefit of the series elastic actuator is two-fold. First, it permits closed-loop tether tension control with lower mass and power consumption than a comparable torque motor. Second, it improves the 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. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA: Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2018 en_US
dc.title Series Elastic Tether Management for Rappelling Rovers en_US
dc.type Preprint en_US

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