Shape Memory Alloy (SMA) Actuators and Their Applications

A special issue of Actuators (ISSN 2076-0825). This special issue belongs to the section "Actuator Materials".

Deadline for manuscript submissions: closed (1 October 2024) | Viewed by 6665

Special Issue Editors


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Guest Editor
Department of Systems Engineering and Automation, Universidad Carlos III de Madrid, Madrid, Spain
Interests: SMA actuators; rehabilitation devices; soft robotics; robot control; sensors

E-Mail Website
Guest Editor
Robotics Laboratory, Department of Systems Engineering and Automation, Carlos III University of Madrid, 28911 Leganés, Madrid, Spain
Interests: design and control of robotic exoskeletons for rehabilitation; emerging actuation technologies in robotics
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Robotics Laboratory, Department of Systems Engineering and Automation, Carlos III University of Madrid, 28911 Leganés, Madrid, Spain
Interests: robotic rehabilitation; emerging actuators for robotics; SLAM; path planning; localization.
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In recent years, emerging actuators such as shape memory alloy (SMA)-based actuators have made it possible to overcome the current limitations of conventional actuators by being integrated into various applications, including medical robotics, rehabilitation robotics, automotive and aerospace industry applications, and more.

Due to their promising properties, SMA-based actuators have received much attention from researchers, where topics related to materials, actuator design, and control are addressed to improve their performance depending on the final application.

This Special Issue addresses research on SMA-based actuators from fundamental studies to their final applications. Original research and review articles are recommended. Topics include, but are not limited to, the following:

  • Control of SMA actuators;
  • Emerging design and fabrication of SMA actuators;
  • Performance assessment of SMA (e.g., electrical power consumption, efficiency);
  • Sensorless actuator;
  • SMA actuators for robotic applications.

Dr. Dorin Sabin Copaci
Prof. Dr. Maria Dolores Blanco Rojas
Prof. Dr. Luis Enrique Moreno Lorente
Guest Editors

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Keywords

  • shape memory alloy actuator
  • actuator design
  • control
  • sensorless actuator
  • modeling

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Published Papers (5 papers)

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Research

16 pages, 5805 KiB  
Article
Numerical and Experimental Study of a Wearable Exo-Glove for Telerehabilitation Application Using Shape Memory Alloy Actuators
by Mohammad Sadeghi, Alireza Abbasimoshaei, Jose Pedro Kitajima Borges and Thorsten Alexander Kern
Actuators 2024, 13(10), 409; https://doi.org/10.3390/act13100409 - 11 Oct 2024
Viewed by 876
Abstract
Hand paralysis, caused by conditions such as spinal cord injuries, strokes, and arthritis, significantly hinders daily activities. Wearable exo-gloves and telerehabilitation offer effective hand training solutions to aid the recovery process. This study presents the development of lightweight wearable exo-gloves designed for finger [...] Read more.
Hand paralysis, caused by conditions such as spinal cord injuries, strokes, and arthritis, significantly hinders daily activities. Wearable exo-gloves and telerehabilitation offer effective hand training solutions to aid the recovery process. This study presents the development of lightweight wearable exo-gloves designed for finger telerehabilitation. The prototype uses NiTi shape memory alloy (SMA) actuators to control five fingers. Specialized end effectors target the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints, mimicking human finger tendon actions. A variable structure controller, managed through a web-based Human–Machine Interface (HMI), allows remote adjustments. Thermal behavior, dynamics, and overall performance were modeled in MATLAB Simulink, with experimental validation confirming the model’s efficacy. The phase transformation characteristics of NiTi shape memory wire were studied using the Souza–Auricchio model within COMSOL Multiphysics 6.2 software. Comparing the simulation to trial data showed an average error of 2.76°. The range of motion for the MCP, PIP, and DIP joints was 21°, 65°, and 60.3°, respectively. Additionally, a minimum torque of 0.2 Nm at each finger joint was observed, which is sufficient to overcome resistance and meet the torque requirements. Results demonstrate that integrating SMA actuators with telerehabilitation addresses the need for compact and efficient wearable devices, potentially improving patient outcomes through remote therapy. Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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18 pages, 1163 KiB  
Article
Adaptive Nonsingular Fast Terminal Sliding Mode Control for Shape Memory Alloy Actuated System
by Xiaoguang Li, Wenzhuo Zhi, Enming Shi, Xiaoliang Fan, Ming Zhao and Bi Zhang
Actuators 2024, 13(9), 367; https://doi.org/10.3390/act13090367 - 19 Sep 2024
Viewed by 723
Abstract
Due to its high power-to-weight ratio, low weight, and silent operation, shape memory alloy (SMA) is widely used as a muscle-like soft actuator in intelligent bionic robot systems. However, hysteresis nonlinearity and multi-valued mapping behavior can severely impact trajectory tracking accuracy. This paper [...] Read more.
Due to its high power-to-weight ratio, low weight, and silent operation, shape memory alloy (SMA) is widely used as a muscle-like soft actuator in intelligent bionic robot systems. However, hysteresis nonlinearity and multi-valued mapping behavior can severely impact trajectory tracking accuracy. This paper proposes an adaptive nonsingular fast terminal sliding mode control (ANFTSMC) scheme aimed at enhancing position tracking performance in SMA-actuated systems by addressing hysteresis nonlinearity, uncertain dynamics, and external disturbances. Firstly, a simplified third-order actuator model is developed and a variable gain extended state observer (VGESO) is employed to estimate unmodeled dynamics and external disturbances within finite time. Secondly, a novel nonsingular fast terminal sliding mode control (NFTSMC) law is designed to overcome singularity issues, reduce chattering, and guarantee finite-time convergence of the system states. Finally, the ANFTSMC scheme, integrating NFTSMC with VGESO, is proposed to achieve precise position tracking for the prosthetic hand. The convergence of the closed-loop control system is validated using Lyapunov’s stability theory. Experimental results demonstrate that the external pulse disturbance error of ANFTSMC is 8.19°, compared to 19.21° for the comparative method. Furthermore, the maximum absolute error for ANFTSMC is 0.63°, whereas the comparative method shows a maximum absolute error of 1.03°. These results underscore the superior performance of the proposed ANFTSMC algorithm. Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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21 pages, 8722 KiB  
Article
Morphing Spoiler for Adaptive Aerodynamics by Shape Memory Alloys
by Aniello Riccio, Andrea Sellitto and Miriam Battaglia
Actuators 2024, 13(9), 330; https://doi.org/10.3390/act13090330 - 1 Sep 2024
Viewed by 954
Abstract
The automotive industry is continuously looking for innovative solutions to improve vehicle aerodynamics and efficiency. The research introduces a significant breakthrough in the field of automotive aerodynamics by employing shape memory alloys as bistable actuators for spoilers and moving flaps. The main novelty [...] Read more.
The automotive industry is continuously looking for innovative solutions to improve vehicle aerodynamics and efficiency. The research introduces a significant breakthrough in the field of automotive aerodynamics by employing shape memory alloys as bistable actuators for spoilers and moving flaps. The main novelty of this research lies in the development of a bistable actuator made of shape memory alloys as a precise and accurate control mechanism for spoilers and movable flaps. The shape memory alloys, with their unique ability to maintain two stable configurations and switch rapidly from one to the other in response to thermal or mechanical stimuli, allow precise and rapid adjustment of aerodynamic surfaces. The main advantage of this technology is its ability to improve vehicle aerodynamics by optimising both drag and downforce, thereby improving vehicle performance and fuel efficiency. This research shows the promising potential of a single composition of NiTi as a revolutionary technology in the automotive industry, revolutionising the way spoilers and moving flaps are used to achieve superior vehicle performance. Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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20 pages, 4200 KiB  
Article
Study of Self-Excited Thermomechanical Oscillator with Shape Memory Alloys
by Ivo Yotov, Georgi Todorov and Todor Todorov
Actuators 2024, 13(5), 182; https://doi.org/10.3390/act13050182 - 11 May 2024
Viewed by 1065
Abstract
In this paper, a new type of self-excited thermomechanical oscillator containing an oscillating shape memory alloy (SMA) filament with two symmetrically arranged spheres is investigated. The self-excitation of the oscillations is due to a heater of constant temperature, which causes periodic contractions of [...] Read more.
In this paper, a new type of self-excited thermomechanical oscillator containing an oscillating shape memory alloy (SMA) filament with two symmetrically arranged spheres is investigated. The self-excitation of the oscillations is due to a heater of constant temperature, which causes periodic contractions of the filament when it approaches it. The contracted filament moves away from the heater a distance sufficient to cool it. Under the action of the weight of the spheres, the cooled filament re-approaches the heater, causing the above processes to repeat periodically. On the basis of experimental studies, approximating functions of the heater’s heat field distribution are derived. A dynamic model of the oscillator has been created, in which the minor and major hysteresis in the SMA alloy and the distribution of the heat field around the heater have been taken into account. Through numerical solutions of the differential equations, the laws of motion of the spheres are obtained. The displacements of the spheres in two perpendicular directions were measured using an experimental system. The obtained experimental results validate the proposed dynamic model and its assumptions with a high degree of confidence. Conclusions are drawn about the stochastic nature of the oscillations due to the hysteresis properties of the SMA and the temperature variation of the natural frequency of the oscillating system. Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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22 pages, 16004 KiB  
Article
A Novel Cooling Design for an Agonistic–Antagonistic SMA Tendon-Driven Actuator
by Renke Liu, Shuyao Zhang, Yusuke Baba and Hideyuki Sawada
Actuators 2023, 12(11), 415; https://doi.org/10.3390/act12110415 - 7 Nov 2023
Cited by 1 | Viewed by 1906
Abstract
Shape memory alloys (SMAs) exhibit a unique property that undergoes deformation in response to temperature variation. This characteristic can be utilized via the application of a filiform SMA wire to tendon-driven robotic actuators for biomimetic joint movements. However, due to the inefficiencies in [...] Read more.
Shape memory alloys (SMAs) exhibit a unique property that undergoes deformation in response to temperature variation. This characteristic can be utilized via the application of a filiform SMA wire to tendon-driven robotic actuators for biomimetic joint movements. However, due to the inefficiencies in heat dissipation, conventional SMA tendon-driven actuators are characterized by their lower relaxation speeds than other actuators. This paper proposes a novel cooling design for an SMA tendon-driven actuator using thin-fin heat sinks based on a multi-layer wrapped SMA tendon design. In addition, the electric circuit and the controller are refined. Prototype devices are constructed to validate the performance of SMA-based actuators under PID control. The results indicate that the proposed design exceeds previous models in terms of relaxation performance by up to 5.8 times while also being able to stabilize at a target angle within 0.5 s under control. Full article
(This article belongs to the Special Issue Shape Memory Alloy (SMA) Actuators and Their Applications)
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