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

This article presents a soft crawling robot prototype with a simple architecture inspired by inchworms. The robot functionally integrates the torso (body) and feet in a monolithic curved structure that only needs a single shape memory alloy coil and differential friction to actuate it. A novel foot configuration is proposed, which makes the two feet, with an anti-symmetrical friction layout, can be alternately anchored, to match the contraction–recovery sequence of the body adaptively. Based on the antagonistic configuration between the shape memory alloy actuator and the elastic body, a vertically auxiliary spring was adopted to enhance the interaction mechanism. Force and kinematic analysis was undertaken, focusing on the parametric design of the special foot configuration. A miniature robot prototype was then 3D-printed (54 mm in length and 9.77 g in weight), using tailored thermoplastic polyurethane elastomer as the body material. A series of experimental tests and evaluations were carried out to assess its performance under different conditions. The results demonstrated that under appropriate actuation conditions, the compact robot prototype could accomplish a relative speed of 0.024 BL/s (with a stride length equivalent to 27% of its body length) and bear a load over five times to its own weight.

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A Soft Five-Fingered Hand Actuated by Shape Memory Alloy Wires: Design, Manufacturing, and Evaluation

Frontiers in Robotics and AI ◽

10.3389/frobt.2020.608841 ◽

2020 ◽

Vol 7 ◽

Author(s):

Filomena Simone ◽

Gianluca Rizzello ◽

Stefan Seelecke ◽

Paul Motzki

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Force Measurement ◽

Optimal Placement ◽

Flexible Structure ◽

Flexible Joints ◽

3D Printed

This work presents a novel five-fingered soft hand prototype actuated by Shape Memory Alloy (SMA) wires. The use of thin (100 μm diameter) SMA wire actuators, in conjunction with an entirely 3D printed hand skeleton, guarantees an overall lightweight and flexible structure capable of silent motion. To enable high forces with sufficiently high actuation speed at each fingertip, bundles of welded actuated SMA wires are used. In order to increase the compliance of each finger, flexible joints from superelastic SMA wires are inserted between each phalanx. The resulting system is a versatile hand prototype having intrinsically elastic fingers, which is capable to grasp several types of objects with a considerable force. The paper starts with the description of the finger hand design, along with practical considerations for the optimal placement of the superelastic SMA in the soft joint. The maximum achievable displacement of each finger phalanx is measured together with the phalanxes dynamic responsiveness at different power stimuli. Several force measurement are also realized at each finger phalanx. The versatility of the prototype is finally demonstrated by presenting several possible hand configurations while handling objects with different sizes and shapes.

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A 3D Printed Implantable Device for Voiding the Bladder Using Shape Memory Alloy (SMA) Actuators

Advanced Science ◽

10.1002/advs.201700143 ◽

2017 ◽

Vol 4 (11) ◽

pp. 1700143 ◽

Cited By ~ 16

Author(s):

Faezeh Arab Hassani ◽

Wendy Yen Xian Peh ◽

Gil Gerald Lasam Gammad ◽

Roshini Priya Mogan ◽

Tze Kiat Ng ◽

...

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Implantable Device ◽

Sma Actuators ◽

3D Printed

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Microanalysis of the Cross-sectional Surface of 3D Printed NiMnGa Magnetic Shape Memory Alloy Using Electron Microscopy and Nanoindentation

Microscopy and Microanalysis ◽

10.1017/s1431927620020814 ◽

2020 ◽

Vol 26 (S2) ◽

pp. 2208-2210

Author(s):

Constantin Solomon ◽

Yash Trivedi ◽

Christopher Bansah ◽

Matthew Caputo

Keyword(s):

Electron Microscopy ◽

Shape Memory Alloy ◽

Shape Memory ◽

Magnetic Shape Memory ◽

Cross Sectional ◽

Magnetic Shape Memory Alloy ◽

3D Printed ◽

The Cross ◽

Sectional Surface

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Curved shape memory alloy-based soft actuators and application to soft gripper

Composite Structures ◽

10.1016/j.compstruct.2017.05.056 ◽

2017 ◽

Vol 176 ◽

pp. 398-406 ◽

Cited By ~ 42

Author(s):

Hugo Rodrigue ◽

Wei Wang ◽

Dong-Ryul Kim ◽

Sung-Hoon Ahn

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Soft Actuators

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Flexible shape memory alloy actuators for soft robotics: Modelling and control

International Journal of Advanced Robotic Systems ◽

10.1177/1729881419886747 ◽

2020 ◽

Vol 17 (1) ◽

pp. 172988141988674 ◽

Cited By ~ 4

Author(s):

Dorin-Sabin Copaci ◽

Dolores Blanco ◽

Alejandro Martin-Clemente ◽

Luis Moreno

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Linear Models ◽

Complex Dynamics ◽

Weight Ratio ◽

Model Free ◽

Wearable Robots ◽

Robotic Devices ◽

Soft Actuators ◽

And Control

One of the limitations in the development of really soft robotic devices is the development of soft actuators. In recent years, our research group has developed a new flexible shape memory alloy actuator that provides more freedom of movements and a better integration in wearable robots, especially in soft wearable robots. Shape memory alloy wires present characteristics such as force/weight ratio, low weight, and noiseless actuation, which make them an ideal choice in these types of applications. However, the control strategy must take into account its complex dynamics due to thermal phase transformation. Different control approaches based on complex non-linear models and other model-free control methods have been tested on real systems. Some exoskeleton prototypes have been developed, which demonstrate the utility of this actuator and the advantages offered by these flexible actuators to improve the comfort and adaptability of exoskeletons.

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Midcarpal Arthrodesis Biomechanics: Memory Staples versus Cannulated Screws

The Journal of Hand Surgery (Asian-Pacific Volume) ◽

10.1142/s2424835518500455 ◽

2018 ◽

Vol 23 (04) ◽

pp. 474-478 ◽

Cited By ~ 1

Author(s):

James P. Ledgard ◽

Javariah Siddiqui ◽

Matthew H. Pelletier ◽

William R. Walsh ◽

Peter J. Scougall

Keyword(s):

Shape Memory Alloy ◽

Shape Memory ◽

Peak Torque ◽

Cannulated Screws ◽

Treatment Groups ◽

Headless Compression Screws ◽

3D Printed ◽

Almost All ◽

Midcarpal Joint ◽

Midcarpal Arthrodesis

Background: Midcarpal arthrodesis is a treatment of choice in patients with midcarpal arthritis. Traditionally a four corner fusion has been favoured, however recent research has shown improved results when the triquetrum and scaphoid are excised. There is no clear evidence as to which remaining bones should be fused or which implants should be used. The purpose of this study is to compare the biomechanics of midcarpal arthrodesis after scaphoid and triquetrum excision, using memory staples or cannulated screws, in recognised construct patterns. Methods: 36 identical sets of carpal bones were 3D printed from acetyl butyl styrene. Midcarpal arthrodeses were performed in three configurations with shape memory alloy staples or headless compression screws. This gave 6 treatment groups; lunocapitate single staple or screw, lunocapitate with 2 staples or screws, three corner fusion with 2 staples or screws. Peak torque to distraction was measured and analysed. Results: The peak torque to distraction was significantly greater in almost all constructs utilizing screws compared to staples, with two lunocapitate screws having the highest peak torque at both 1 and 3 mm distraction with 244 Nmm and 749 Nmm respectively (p < 0.05). Conclusions: Constructs utilizing screws have a peak torque to distraction significantly higher when compared to staples. Our recommendation when performing a midcarpal arthrodesis after scaphoid and trapezium excision is to fuse the midcarpal joint with 2 headless compression screws.

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