A bio-inspired shape memory alloy composite (BISMAC) actuator

Abstract

A beam-shape composite actuator using shape memory alloy (SMA) wires as the active component, termed a Bio-Inspired Shape Memory Alloy Composite (BISMAC), was designed to provide a large deformation profile. The BISMAC design was inspired by contraction of a jellyfish bell, utilizing the rowing mechanism for locomotion. Characterization of maximum deformation in underwater conditions was performed for different actuator configurations to analyze the effect of different design parameters, including silicone thickness, flexible steel thickness and distance between the SMA and flexible steel. A constant cross-section (CC)-BISMAC of length 16 cm was found to achieve deformation with a radius of curvature of 3.5 cm. Under equilibrium conditions, the CC-BISMAC was found to achieve 80% of maximum deformation, consuming 7.9 J/cycle driven at 16.2 V/0.98 A and a frequency of 0.25 Hz. A detailed analytical model was developed using the transfer matrix method and a 1D finite beam element (FE) model to simulate the behavior of the BISMAC incorporating gravity, buoyancy and SMA parameters. The FE and transfer matrix models had a maximum deformation error norm of 1.505 and 1.917 cm in comparison with experimentally observed beam deformation in the CC-BISMAC. The mean curvatures predicted by the FE and transfer matrix methods were 0.292 cm −1 and 0.295 cm −1 compared to a mean experimental curvature of 0.294 cm −1 , a percentage error of −5.4% and 2.77%, respectively. Using the developed analytical model, an actuator design was fabricated mimicking the maximum deformation profile of jellyfish of the species Aurelia aurita (AA). The designed AA-BISMAC achieved a maximum curvature of 0.428 cm −1 as compared to 0.438 cm −1 for A. aurita with an average square root error of 0.043 cm −1 , 10.2% of maximum A. aurita curvature.

Flexible Robotic Spine Actuated by Shape Memory Alloy

“…G. Zhou set up an experiment to study the dynamic deflection [24]. The stress and deformation profile of such mechanisms have also been investigated in some studies about SMA actuators for biomimetic robots [25][26]. In [27], A. S. Veeramani studied the dynamic behaviour of an SMA-actuated catheter.…”

Miniature Shape Memory Alloy Heat Engine for Powering Wireless Sensor Nodes

“…The mechanism is based on the shape memory alloy (SMA) that exhibits memory effect which translates into a mechanical force when driven beyond the austenite finish temperature. SMAs have been utilized in numerous actuations and sensing applications (Kudva 2004;Morgan 2004;Villanueva et al 2010;Villanueva, Smith, and Priya 2011;Tadesse et al 2012). They have also been explored for heat engine applications, where the first one was developed more than half a century ago (Banks 1975).…”

Working principle of bio-inspired shape memory alloy composite actuators

“…Recently, bio-inspired shape memory alloy composite (BISMAC) actuators have demonstrated the ability to translate the relatively high-force (70 gf) and low-strain (4%) of SMA wire into low-force and giant bending deformations [4]. BISMAC actuators were developed for use in unmanned undersea vehicles (UUVs) inspired by jellyfish species Aurelia aurita which requires axial displacements up to 42%.…”

“…Further, the surface of BISMAC is hydrophobic which makes them directly operable in water. This opens up the possibility of developing various robotic systems such as biomimetic jellyfish [4], a hexapod stick insect [6], a mechatronic fish propelled by its tail [7], and a ray with oscillating fins [8]. SMA-based actuators have been previously deployed in two underwater robots: a lobster [9] and a lamprey [10].…”

“…The initial and final positions of the actuator were recorded using a high speed camera (Fastec Imaging IN250). The actuator was positioned in the tank using the method described by Villanueva et al [4]. Incremental weights in steps of 0.5 g were used to load the actuator for the blocking force calculation.…”