An Overview of Shape Memory Alloy-Coupled Actuators and Robots

Abstract

The one-dimensional deformation of shape memory alloy (SMA) wires and springs can be implemented into different types of functional structures with three-dimensional deformations. These structures can be classified based on the type of structure and how the SMA element has been implemented into the following categories: rigid mechanical joints, semi-rigid flexural hinges, SMA elements externally attached to a soft structure, and embedded into the soft structure. These structures have a wide range of properties and implementation requirements, and they have been used to produce a variety of robots with rigid and soft motions. The different research efforts to develop actuators and robots related to each type of structure are presented along with their respective strengths and weaknesses. A model is then developed to discuss the performance and applicability of SMA wires versus SMA springs for actuators with a polymeric matrix to see the effect of each type of SMA on the selection of design parameters. A comparison of the different types of structures and the applicability of different types of SMA elements for different types of structures is then presented.

Self-Healing and Damage Resilience for Soft Robotics: A Review

“…SMAs and SMPs are common actuator tools that have been used frequently in soft robotics applications (Ionov, 2011;Albu-Schäffer and Bicchi, 2016;Hou, 2016;Rodrigue et al, 2017), but they have only occasionally been used as variable-stiffness structural materials (Manti et al, 2016). Their ability to autonomously restore form after plastic deformation parallels the motivations of self-healing and damage resilience as presented thus far.…”

Multimaterial 3D Printed Soft Actuators Powered by Shape Memory Alloy Wires

“…Shape memory alloys (SMAs) are a class of active materials that can perform reversible actuation upon thermomechanical training [1]. Although SMAs are manufactured in a variety of shapes, including plates, springs, wires, and ribbons, the most widely used shape is the onedimensional SMA wire, which can be integrated into soft matrices to fabricate actuators that transform one-dimensional deformation of the SMA wires into a broad range of three-dimensional deformations.…”

Automatic Design of Soft Dielectric Elastomer Actuators With Optimal Spatial Electric Fields

“…Soft actuators are the key enabling component for motion generation in such applications. During the past decade, broad categories of soft actuators have been developed, including pneumatic and fluidic actuators [6]- [10], shape memory polymers [11], [12], etc. Among them, dielectric elastomer actuators (DEAs), capable of deforming in response to electric fields, are promising owing to their interesting attributes such as large voltage-induced deformation, rapid response and high energy density [13]- [17].…”