Modeling and characterization of shape memory alloy springs with water cooling strategy in a neurosurgical robot

Cheng, Shing Shin; Kim, Yeongjin; Desai, Jaydev P.

doi:10.1177/1045389x16685443

Cited by 49 publications

(25 citation statements)

References 56 publications

(99 reference statements)

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“…However, the strain that the actuator can produce is relatively low (<8% of its initial length) [46], which is insufficient for the use in making a wearable robot. In order to enhance actuating performance, SMA can be shaped in the shape of coiled springs that result in substantially larger displacement when it is utilized as an actuator [46,[55][56][57][58][59]. The coil spring shaped SMA actuators have large extension strain over 200% [46,55], which is enough for the desired application as the strain of a SMA coil spring is larger than that exhibited by human muscles [60].…”

Section: Design Of Muscle-like Actuator Based On Shape Memory Alloy (mentioning

confidence: 99%

“…Generally, many SMA-based actuators are operated in ambient air, which offers a fast heating rate, but the limitation is a slow cooling rate as well [46][47][48][49]59]. To enhance the response speed of SMA based actuators, a few works have applied water as an alternative coolant during the actuation of the SMA [50,[55][56][57][58]. Park et al developed SMA coil spring-based actuator that was composed of the SMA coil spring bundles and a stretchable polymer tube that can stretch over 300% of its initial length [55][56][57].…”

Section: Design Of Muscle-like Actuator Based On Shape Memory Alloy (mentioning

confidence: 99%

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Design of Shape Memory Alloy-Based Soft Wearable Robot for Assisting Wrist Motion

et al. 2019

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In this paper, we propose a shape memory alloy (SMA)-based wearable robot that assists the wrist motion for patients who have difficulties in manipulating the lower arm. Since SMA shows high contraction strain when it is designed as a form of coil spring shape, the proposed muscle-like actuator was designed after optimizing the spring parameters. The fabricated actuator shows a maximum force of 10 N and a maximum contraction ratio of 40%. The SMA-based wearable robot, named soft wrist assist (SWA), assists 2 degrees of freedom (DOF) wrist motions. In addition, the robot is totally flexible and weighs 151g for the wearable parts. A maximum torque of 1.32 Nm was measured for wrist flexion, and a torque of larger than 0.5 Nm was measured for the other motions. The robot showed the average range of motion (ROM) with 33.8, 30.4, 15.4, and 21.4 degrees for flexion, extension, ulnar, and radial deviation, respectively. Thanks to the soft feature of the SWA, time cost for wearing the device is shorter than 2 min as was also the case for patients when putting it on by themselves. From the experimental results, the SWA is expected to support wrist motion for diverse activities of daily living (ADL) routinely for patients.

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Section: Design Of Muscle-like Actuator Based On Shape Memory Alloy (mentioning

confidence: 99%

Section: Design Of Muscle-like Actuator Based On Shape Memory Alloy (mentioning

confidence: 99%

Design of Shape Memory Alloy-Based Soft Wearable Robot for Assisting Wrist Motion

et al. 2019

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“…Since NITINOL is non magnetic this characteristic can be used as an actuator principle for "close to bore" MRI applications. 20…”

Section: Actuator Principlesmentioning

confidence: 99%

<p>NITINOL-based actuator for device control even in high-field MRI environment</p>

Kalmar¹,

Boese²,

Maldonado³

et al. 2019

MDER

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Background: The magnetic resonance imaging (MRI) environment with its high-strength magnetic fields requires specialized and sometimes sophisticated solutions for otherwise simple problems. One of these problems is MR-compatible actuator mechanisms that transfer a signal into an action. Purpose: Normal actuators are based on a magnetic effect (eg, relays) and will typically not work in magnetic fields exceeding 1000 G, eg, inside the bore of an MR scanner. To enable the use of clinical devices inside the MRI, eg, for interventional procedures, there is a need for fully compatible actuators. Patients and methods: Various actuators were compared for the purpose as a simple onoff switch within an MRI. NITNOL wire as an actuator showed the highest potential because of its simplicity and reliability. We tested the possible force achieved by the NITINOL wire related to the respective energy consumption, to provide a travel range of 2 mm. Results: Compared to other actuators, the NITNOL wire is cheaper and requires less space. In the switching process however, there is a delay due to the time required for the heating of the wire up to the transformation temperature. The NITINOL switch shows a reliable behavior with regard to the generated force and the switching path over the entire measurement. Significant artifacts, caused by the NITNOL wire could not be detected in the MRI. Conclusion: NITINOL wires can be repeatedly used, are relatively easy to implement and could be an economic alternative to other more complicated actuator technologies.

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“…Note also that the Joule effect is fast to employ for heating, thanks to the metallic nature of SMAs [19,20], whereas efficient cooling generally requires sophisticated devices [21][22].…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis of a prestressed mechanism with multi-antagonistic and hysteretic SMA actuation

Boufayed¹,

Chapelle²,

Destrebecq³

et al. 2020

Meccanica

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This paper deals with the specific hysteretic effects of a multi-antagonistic shapememory alloy (SMA) actuation system in which each wire can be thermally activated individually (one or more at a time). A planar system with six SMA wires organized in a ternary rotational symmetry is studied numerically, via finite element calculation software. The objective is to analyze the functional characteristics of such mechanism, whose response during a thermal activation sequence is multi-antagonistic and hysteretic. Important points are highlighted, such as the avoidance of buckling and plasticity, the possibility of locking a configuration without energy input, and the "attraction" effect of any heating step on the following steps. The feasibility of reaching a given target in the workspace is also illustrated. Finally, the analysis shows the necessity to consider these multi-antagonistic and hysteretic aspects of the actuation in the future design and control of such type of mechanisms. The latter could be of interest as hollow shaft rotary actuators with additional (small) translation degrees of freedom in applications requiring long-term and stable positioning at ambient temperature.

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Modeling and characterization of shape memory alloy springs with water cooling strategy in a neurosurgical robot

Cited by 49 publications

References 56 publications

Design of Shape Memory Alloy-Based Soft Wearable Robot for Assisting Wrist Motion

Design of Shape Memory Alloy-Based Soft Wearable Robot for Assisting Wrist Motion

<p>NITINOL-based actuator for device control even in high-field MRI environment</p>

Finite element analysis of a prestressed mechanism with multi-antagonistic and hysteretic SMA actuation

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