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Effect of compliance location in series elastic actuators

Published online by Cambridge University Press:  07 June 2013

Jonathon W. Sensinger*
Affiliation:
Rehabilitation Institute of Chicago, Center for Bionic Medicine, Chicago, Illinois, USA Physical Medicine and Rehabilitation/Mechanical Engineering, Northwestern University, Chicago, Illinois, USA
Lawrence E. Burkart
Affiliation:
Kyocera, San Diego, California, USA
Gill A. Pratt
Affiliation:
Franklin W. Olin College of Engineering, Needham, Massachusetts, USA Defense Advanced Research Projects Agency, Arlington, Virginia, USA
Richard F. ff. Weir
Affiliation:
Department of Bioengineering, University of Colorado, Denver, Colorado, USA VA Eastern Colorado Health Care System, Aurora, Colorado, USA
*
*Corresponding author. E-mail: sensinger@ieee.org

Summary

Series elastic actuators have beneficial properties for some robot applications. Several recent implementations contain alternative placements of the compliant element to improve instrumentation design. We use a class 1 versus class 2 lever model and energy-port methods to demonstrate in this paper that these alternative placements should still be classified as series elastic actuators. We also note that the compliance of proximal series elastic actuators is reflected by an augmented gear ratio dependent on the nominal gear ratio, which is significant for small gear ratios and approaches unity for large gear ratios. This reflected compliance is shown to differ depending on the sign of the gear ratio. We demonstrate that although the reflected compliance is only marginally influenced by the magnitude of the gear ratio, there are several notable differences, particularly for small gear ratios.

Type
Articles
Copyright
Copyright © Cambridge University Press 2013 

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