Design of a novel flexible shape memory alloy actuator with multilayer tubular structure for easy integration into a confined space

Leng, Jiaming; Yan, Xiangqiao; Huang, Dawei; Gao, Zhenjian

doi:10.1088/0964-1726/25/2/025007

Cited by 24 publications

(25 citation statements)

References 32 publications

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“…We investigated differences in contraction due to the number of loops present in a coiled tubeguided SMA wire actuator. It was expected that increasing the number of loops would negatively impact contraction, as predicted by the capstan equation [23], which describes how friction influences the holding force of a loaded, flexible line lying along the surface of a cylinder. A 1000 mm long tube- The length of each acrylic plate was 290 mm, matching the length of the SMA wire in the straight contraction experiment, however the turn radius experiment featured a long tube-guided SMA wire actuator with a single turn.…”

Section: Number Of Loopsmentioning

confidence: 99%

“…The tube-guided SMA wire actuator concept has been applied to an anthropomorphic robotic hand [21] and to soft wearable robots [22], as well as investigated as a concept for integration of actuators into confined spaces [23]. In those studies, there has been some exploration of the trade-offs associated with the use of tube-guided SMA wire actuators.…”

Section: Introductionmentioning

confidence: 99%

“…This was found to impair the SMA wire stroke, which was attributed to increased friction [22]. Another study varied the angle by which a tube-guided SMA wire actuator was wound around a 200 mm diameter cylinder, demonstrating that when the SMA wire was wound around the entire cylinder (winding angle 360 • ), the stroke was impaired by up to 35%, similarly attributed to friction [23]. However, both studies focused on the concept and design of tube-guided SMA wire actuators rather than characterizing them in depth.…”

Section: Introductionmentioning

confidence: 99%

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

2019

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Smart textiles are flexible materials with interactive capabilities such as sensing, actuation, and computing, and in recent years have garnered considerable interest. Shape-memory alloy (SMA) wire is a well-suited for smart textiles due to its high strength, small size, and low mass. However, the contraction of SMA wire is low, limiting its usefulness. One solution to increasing net contraction is to use a long SMA wire and guide it inside a tube that is wound back and forth or coiled inside a smart textile. In this article, we characterize the performance of tube-guided SMA wire actuators. We investigate the effect of turn radius and number of loops, showing that the stroke of an SMA-based system can be improved by up to 69.81% using the tube-guided SMA wire actuator concept. Finally, we investigate how tube-guided SMA wire actuators can be lubricated to improve their performance. Coarse graphite powder and tungsten disulfide lubricant both delivered improvements in stroke compared with an unlubricated system.

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Section: Number Of Loopsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2019

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“…SMAs in a wire geometry are particularly suited for tensile actuation due to their comparatively higher efficiency (by weight) and uniformity of generated stress over the cross‐sectional area of the device. Numerous wire‐based actuators have been described 36,39–42. For example, Allen et al employ a Nitinol wire embedded with a polycaprolactone (PCL) rod, both of which are encapsulated in a silicone rubber to form a composite actuator ( Figure a) 43.…”

Section: Shape Memory Alloysmentioning

confidence: 99%

Materials as Machines

2020

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of responsive materials as machines is in robotics. The vision, leadership, and research of Bar-Cohen is seminal in both invigorating and focusing current-day research activities to develop responsive materials [2] and implement [3] them as lightweight, dexterous, and gentle (e.g., soft) robotic elements. In this spirit, this review exhaustively details the materials, the nature of their stimuli-response, and discusses considerations for their implementation in robotic systems and subsystems.Robotics is a well-established but growing field of research. Sustained progress in both performance and functionality continue to be realized in commercial robotic systems largely based on conventional materials and their integration with mechanisms. A recent example is the Atlas robot from Boston Dynamics [4] (Figure 1a). The incorporation of stimuli-responsive materials in robotics has largely focused on component-level demonstrations to extend the performance of a subsystem (such as a hand or gripper).Stimuli-responsive materials, spanning nearly all classes of materials and size scales, are currently subject to widespread examination in corporate, government, and academic research laboratories (Figure 1b-d). [5][6][7] In some cases, these materials have already found widespread commercial implementation in end use and are comparatively mature. The materials and fundamentals of their responses are summarized in Figure 2. Shape memory alloys (SMAs) and ceramic piezoelectric materials are distinctive in that they are hard, stimuli-responsive materials. Deformation of these materials can produce large energy densities due to their inherent stiffness. Electroactive polymers (EAPs) remain a topic of considerable interest, particularly dielectric elastomer actuators (DEAs). Engineered systems are rapidly emerging and enabling performance gains in robotics, largely based on pneumatic or fluidic (such as HASEL [8] actuators) transport processes that localize deformation to generate force or produce motion. Soft materials, such as shape memory polymers (SMPs), hydrogels, and liquid crystalline polymer networks (LCNs) and elastomers (LCEs) may offer distinctive functional performance to robotic systems in allowing local control of deformation without the need for complex interfacing with mechanisms. As will be evident, each of these materials has inherent advantages and performance tradeoffs that must be considered in functional implementations. However, responsive material systems have a common obstacle to widespread use: the performance and Machines are systems that harness input power to extend or advance function. Fundamentally, machines are based on the integration of materials with mechanisms to accomplish tasks-such as generating motion or lifting an object. An emerging research paradigm is the design, synthesis, and integration of responsive materials within or as machines. Herein, a particular focus is the integration of responsive materials to enable robotic (machine) functions such as gripping, lifting, or motility (walk...

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“…With this starting point, the work presented in this paper analyzes different configurations for a flexible actuator based on SMA approaches with different materials and different mechanical design, giving the possibility to increase the total displacement. A flexible SMA-based actuator was presented in [8,17]. However, an analysis of the flexible actuator with multiple SMA wires in parallel (in the same Bowden or independently, with each one in one Bowden) according to the work frequency and efficiency, from the author's knowledge was not made.…”

Section: Introductionmentioning

confidence: 99%

Flexible Shape-Memory Alloy-Based Actuator: Mechanical Design Optimization According to Application

2019

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New robotic applications, among others, in medical and related fields, have in recent years boosted research in the development of new actuators in the search for solutions that are lighter and more flexible than conventional actuators. Shape-Memory Alloy (SMA)-based actuators present characteristics that make them an excellent alternative in a wide variety of applications. This paper presents the design, tests (with the control description) and analysis of various configurations of actuators based on SMA wires: flexible SMA actuators, different mechanical design to multiply the displacement and different configurations for actuators with multiple SMA wires. The performance of the actuators has been analyzed using wires of different activation temperatures. The influence of the Bowden sheath of the flexible actuator has been tested, as has the thermal behavior of actuators with several wires. This work has allowed determination of the most effective configuration for the development of a flexible actuator based on SMA, from the point of view of dimensions, efficiency, and work frequency. This type of actuator has been applied in the development of soft robots and light robotic exoskeletons.

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Design of a novel flexible shape memory alloy actuator with multilayer tubular structure for easy integration into a confined space

Cited by 24 publications

References 32 publications

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

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

Materials as Machines

Flexible Shape-Memory Alloy-Based Actuator: Mechanical Design Optimization According to Application

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