Free strain gradient reversal of a variable recruitment fluidic artificial muscle bundle

Jeong Yong Kim; Nicholas Mazzoleni; Matthew Bryant

doi:10.1117/12.2583213

22 March 2021 Free strain gradient reversal of a variable recruitment fluidic artificial muscle bundle

Jeong Yong Kim, Nicholas Mazzoleni, Matthew Bryant

Proceedings Volume 11586, Bioinspiration, Biomimetics, and Bioreplication XI; 115860L (2021) https://doi.org/10.1117/12.2583213
Event: SPIE Smart Structures + Nondestructive Evaluation, 2021, Online Only

Abstract

This paper investigates the effect of resistive forces that arise in compressed fluidic artificial muscles (FAMs) within a variable recruitment bundle. Much like our skeletal muscle organs that selectively recruit different number of motor fibers depending on the load demand, a variable recruitment FAM bundle adaptively activates the minimum number of motor units (MUs) to increase its overall efficiency. A variable recruitment bundle may operate in different recruitment states (RSs) during which only a subset of the FAMs within a bundle are activated. In such cases, a difference in strain occurs between active FAMs and inactive/low-pressure FAMs. This strain difference results in the compression of inactive/lowpressure FAMs causing them to exert a resistive force opposing the force output of active FAMs. This paper presents experimental measurements for a FAM for both tensile and compressive regions. The data is used to simulate the overall force-strain space of a variable recruitment bundle for when resistive force effects are neglected and when they are included. Counterintuitively, an initial decrease in bundle free strain is observed when a transition to a higher RS is made due to the presence of resistive forces. We call this phenomenon the free strain gradient reversal of a variable recruitment bundle. The paper is concluded with a discussion of the implications of this phenomenon.

Conference Presentation

Citation Download Citation

Jeong Yong Kim, Nicholas Mazzoleni, and Matthew Bryant "Free strain gradient reversal of a variable recruitment fluidic artificial muscle bundle", Proc. SPIE 11586, Bioinspiration, Biomimetics, and Bioreplication XI, 115860L (22 March 2021); https://doi.org/10.1117/12.2583213

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