A turtle-like swimming robot using a smart soft composite (SSC) structure

Abstract

This paper describes the development of a biomimetic swimming robot based on the locomotion of a marine turtle. To realize the smooth, soft flapping motions of this type of turtle, a novel actuator was also developed, using a smart soft composite (SSC) structure that can generate bending and twisting motions in a simple, lightweight structure. The SSC structure is a composite consisting of an active component to generate the actuation force, a passive component to determine the twisting angle of the structure, and a matrix to combine the components. The motion of such a structure can be designed by specifying the angle between a filament of the scaffold structure and a shape-memory alloy (SMA) wire. The bending and twisting motion of the SSC structure is explained in terms of classical laminate theory, and cross-ply and angled-ply structures were fabricated to evaluate its motion. Finally, the turtle-like motion of a swimming robot was realized by employing a specially designed SSC structure. To mimic the posterior positive twisting angle of a turtle’s flipper during the upstroke, the SMA wire on the upper side was offset, and a positive ply-angled scaffold was used. Likewise, for the anterior negative twisting angle of the flipper during the downstroke, an offset SMA wire on the lower side and a positive ply-angled scaffold were also required. The fabricated flipper’s length is 64.3 mm and it realizes 55 mm bending and 24° twisting. The resulting robot achieved a swimming speed of 22.5 mm s−1.

Shape memory alloy (SMA)-based head and neck immobilizer for radiotherapy

“…By adopting this force in an actuation system, we can design a device which has small and simple structure, different from conventional actuators because SMA itself can work as an actuation part and does not requires any additional apart to generate actuation forces. SMA actuators are effective because they can generate high actuation forces and maintain a deformed shape when heat is applied [8]. More importantly, SMA wire interferes little with the radiation environment; i.e., electromagnetic field, compared with motor and gear-based mechanisms [9].…”

Performance Evaluation of a Novel Propulsion System for the Spherical Underwater Robot (SURIII)

“…Hyung-Jung Kim et al developed a turtle-like swimming robot with biomimetic flippers. This robot uses a smart soft composite structure to realize smooth and soft flapping motion [13]. Guo lab in Kagawa University developed an octopus-inspired micro robot using ionic polymer metal composite (IPMC).…”

SMA-based smart soft composite structure capable of multiple modes of actuation

“…Fusible alloy embedded in the matrix has also been used to realize soft actuators capable of shape retention [36]. Anisotropic layers embedded in the matrix have been used to couple the bending deformation with a twisting motion [37]. Anisotropic properties and can help induce actuators in a multitude of types of deformation [38,39], but the orientation of the fibers limit the movement in other modes and other directions of actuation.…”