Variable Stiffness Actuators Embedded with Soft-bodied Polycaprolactone and Shape Memory Alloy Wires*

This article presents a novel variable-stiffness flexible manipulator for minimally invasive surgery. Each module of the proposed manipulator contains a variable-stiffness mechanism actuated by proactive deformation of shape memory alloy. Due to low driving current, apparent mechanical deformation, suitable phase transformation temperature and biocompatibility of shape memory alloy wire actuation, it is well suited for the manipulator applied in minimally invasive surgery, where variable stiffness is urgently required. In this article, the conceptual design, elastic modulus model, thermo-electric model, stiffness controlling method and finite element method simulation for a single module of the proposed variable-stiffness flexible manipulator are presented. Moreover, the memory shape setting experiment of shape memory alloy wire and fabrication of the single module are carried out. Finally, stiffness characterizations of the mechanism and the single module are studied separately, theoretically and experimentally.

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A novel variable stiffness soft finger actuated by shape memory alloy

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-160091 ◽

2017 ◽

Vol 53 (4) ◽

pp. 727-733 ◽

Cited By ~ 4

Author(s):

Junfeng Li ◽

Haibin Yin ◽

Yuegang Tan

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Variable Stiffness ◽

Soft Finger

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A variable stiffness transverse mode shape memory alloy actuator as a minimally invasive organ positioner

The European Physical Journal Special Topics ◽

10.1140/epjst/e2013-01941-9 ◽

2013 ◽

Vol 222 (7) ◽

pp. 1503-1518 ◽

Cited By ~ 2

Author(s):

W. Anderson ◽

A. Eshghinejad ◽

R. Azadegan ◽

C. Cooper ◽

M. Elahinia

Keyword(s):

Shape Memory Alloy ◽

Minimally Invasive ◽

Shape Memory ◽

Mode Shape ◽

Variable Stiffness ◽

Transverse Mode ◽

Shape Memory Alloy Actuator

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Synergistically configured shape memory alloy for variable stiffness translational actuation

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x19828487 ◽

2019 ◽

Vol 30 (6) ◽

pp. 844-854 ◽

Cited By ~ 1

Author(s):

D Nalini ◽

K Dhanalakshmi

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Variable Stiffness ◽

Large Displacement ◽

Linear Actuator ◽

Shape Memory Alloy Wire ◽

Alloy Wire ◽

Active Compliance ◽

Wide Range ◽

Stiffness Profile

The structural composition of two elastic elements, shape memory alloy wire (active actuating element) and spring (the passive bias), offers variable stiffness actuation. Based on this principle, a variable stiffness linear actuator is conceptually designed and developed. It is electromechanical by nature, that is, it is electrically activated and creates translational/linear motion. The variable stiffness linear actuator engages shape memory alloy wire(s) along with a passive compression spring to work synergistically. The biasing element offers recovery force to the shape memory alloy wire as well as compliance to the whole structure. The synergistic configuration exhibits an aiding force, thereby allowing an actuation with large displacement and a wide range of stiffness. The actuator mechanism is implemented through parallel action and further proposes two different modes of operation: pull mode (i.e. the disc moving along a fixed shaft) and push mode (i.e. linear reciprocating motion of the pushrod). The shape memory alloy configured actuator mechanism is analysed theoretically; the working model of the variable stiffness linear actuator is developed and investigated experimentally. The results apprise that the variable stiffness linear actuator is capable of offering large displacement and in reproducing the stiffness profile for active compliance control applications.

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