A bio-inspired electro-active Velcro mechanism using Shape Memory Alloy for wearable and stiffness controllable layers

Abstract

Abstract-Smart attachment mechanisms are believed to contribute significantly in stiffness control of soft robots. This paper presents a working prototype of an active Velcro based stiffness controllable fastening mechanism inspired from micro active hooks found in some species of plants and animals. In contrast to conventional passive Velcro, this active Velcro mechanism can vary the stiffness level of its hooks to adapt to external forces and to maintain the structure of its supported layer. The active hooks are fabricated using Shape Memory Alloy (SMA) wires which can be actuated using LenzJoule heating technique via thermo-electric manipulation. In this paper, we show experimental results for the effects of active SMA Velcro temperature, density and number on the attachment resisting force profile in dynamic displacement. We aim to provide new insights into the novel design approach of using active hook systems to support future implementation of active velcro mechanisms for fabrication of wearable stiffness controllable thin layers.

Climbing Plant‐Inspired Micropatterned Devices for Reversible Attachment

“…[ 16 ] To date, the most famous hook‐based mechanical interlocker is Velcro, which was inspired by burdock seeds. In addition, other anchoring systems for mechanical interlocking have been developed and have shown great potential, including probabilistic and fabric fasteners, [ 6,16,17 ] dry adhesives, [ 7 ] medical patches for skin interlocking, [ 10 ] and microspines for climbing robots [ 18–20 ] or grippers. [ 21,22 ]…”

Toward a low hysteresis helical scale Jamming interface inspired by teleost fish scale morphology and arrangement

“…The hysteresis loss, lack of local stiffness control and low repeatability are also inevitable with jamming based stiffening. While usually the normal forces on the jammed surfaces are controlled for stiffening, in our recent works, we investigated the idea of using low melting point composite [19] and active Velcro attachment mechanisms between the jamming media [20] to achieve higher stiffness range with simpler and smaller actuation mechanism for local stiffens control [16]. A tendon driven design is favorable for its controllability and robustness against environment uncertainties.…”