Characterization and Lubrication of Tube-Guided Shape-Memory Alloy Actuators for Smart Textiles

Helps, Tim; Vivek, Adithya; Rossiter, Jonathan

doi:10.3390/robotics8040094

Cited by 12 publications

(9 citation statements)

References 23 publications

(36 reference statements)

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“…However, this design made it possible to fit a larger contraction into a more compact installation space. This is confirmed by the test results of Helps et al [ 36 ], which show an increased shortening of 69.81% in the same installation space compared to a straight wire.…”

Section: Discussionsupporting

confidence: 74%

Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

2023

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Nature provides a considerable number of good examples for simple and very efficient joint assemblies. One example is the enormously flexible cervical spine of American barn owls, which consists of 14 cervical vertebrae. Each pair of vertebrae produces a comparatively small individual movement in order to provide a large overall movement of the entire cervical spine. The biomimetic replication of such joints is difficult due to the delicate and geometric unrestricted joint shapes as well as the muscles that have to be mimicked. Using X-ray as well as micro-computed tomography images and with the utilisation of additive manufacturing, it was possible to produce the owl neck vertebrae in scaled-up form, to analyse them and then to transfer them into technically usable joint assemblies. The muscle substitution of these joints was realised by smart materials actuators in the form of shape memory alloy wire actuators. This actuator technology is outstanding for its muscle-like movement and for its high-energy density. The disadvantage of this wire actuator technology is the low rate of contraction, which means that a large length of wire has to be installed to generate adequate movement. For this reason, the actuator wires were integrated into additively manufactured carrier components to mimic biological joints. This resulted in joint designs that compensate for the disadvantages of the small contraction of the actuators by intelligently installing large wire lengths on comparatively small installation spaces, while also providing a sufficient force output. With the help of a test rig, the developed technical joint variants are examined and evaluated. This demonstrated the technical applicability of this biomimetic joints.

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Section: Discussionsupporting

confidence: 74%

Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

2023

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“…In general, this design made it possible to fit a larger contraction into a more compact installation space. This is confirmed by the test results of Helps et al [34], which show an increased shortening of 69.81 % in the same installation space compared to a straight wire.…”

Section: Version Helixsupporting

confidence: 70%

Owl Neck Spine inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

Löffler¹,

Tremmel²,

Hornfeck³

2023

Preprint

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Nature provides plenty of good examples for simple and very efficient joint assemblies. One example is the enormously flexible cervical spine of American barn owls, which consists of 14 cervical vertebrae. Each pair of vertebrae produces a comparatively small individual movement in order to provide a large overall movement of the entire cervical spine. The biomimetic replication of such joints is difficult due to the delicate and geometric unrestricted joint shapes as well as the muscles that have to be mimicked. Using X-ray as well as micro computed tomography images and with the utilisation of additive manufacturing, it is possible to produce the owl neck vertebrae in scaled-up form, to analyse them and then to transfer them into technically usable joint assemblies. The muscle substitution of these joints is realised by smart materials actuators in the form of shape memory alloy wire actuators. This actuator technology is outstanding for its muscle-like movement and for its enormous energy density [1,2]. The disadvantage of this wire actuator technology is the low rate of contraction, which means that a large length of wire has to be installed to generate adequate movement. For this reason, the actuator wires are integrated into additively manufactured carrier components to mimic the biological joints. This results in joint designs that compensate for the disadvantages of the small contraction of the actuators by intelligently installing large wire lengths on comparatively small installation spaces, while also providing a sufficient force output. With the help of a test rig, the developed technical joint variants are examined and evaluated. This demonstrates the technical applicability of this bionic joints.

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“…NiTi material transformation strains upon M⇔A transformation commonly reach 6-8% [29] and this transformation strain is often used in soft robotic applications to lift loads and create motion. [41,69,70] Alternatively, if boundary conditions impede the dimensional recovery of an SMA material such that a stretched length is fixed, an increase in temperature above A f will produce an increase in material engineering stress (σ m ) (Figure 1c, path 1-6). Recovery stress between M⇔A transformation can be as high as 500-900 MPa [29,71] and can be leveraged for applications such as dynamic socket fittings, rock-splitters, or mechanical counter pressure spacesuits.…”

Section: Tablementioning

confidence: 99%

Dynamic, Tunable, and Conformal Wearable Compression Using Active Textiles

Granberry

Pettys‐Baker

Woelfle

et al. 2022

Adv Materials Technologies

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New medical compression technologies that are simultaneously low‐profile, facile to don, and dynamic—applying medical compression only when needed—can expand the use of wearable compression, increase patient compliance, and lead to better medical outcomes. Dynamic and conformal wearable compression devices are presented that can be donned in a low‐stiffness state and transition into a high‐stiffness and, consequently, high‐compression state, on‐demand. These devices are enabled by active textiles developed from custom NiTi filaments that remain inactive at room temperature and accomplish actuation proximal to the human body surface. Further, these compression devices exploit NiTi material hysteresis to sustain a high‐compression state post‐heating and upon equilibrium with the body surface temperature for thermally‐comfortable, on‐body performance. Two case study examples—1) a consumer medical compression device and 2) a custom astronaut compression device—demonstrate the generalizability and flexibility of the engineering and design methods to develop a range of dynamic, tunable, and conformal compression devices with different goals and requirements. Further, this work demonstrates a roadmap for developing wearable systems that can accommodate a range of users without sacrificing system performance. This research opens doors for new NiTi‐based medical and consumer applications that interface with the body surface.

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Characterization and Lubrication of Tube-Guided Shape-Memory Alloy Actuators for Smart Textiles

Cited by 12 publications

References 23 publications

Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

Owl-Neck-Spine-Inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

Owl Neck Spine inspired, Additively Manufactured, Joint Assemblies with Shape Memory Alloy Wire Actuators

Dynamic, Tunable, and Conformal Wearable Compression Using Active Textiles

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