A novel smart assistive knee brace incorporated with shape memory alloy wire actuator

2020 ◽  
Vol 31 (13) ◽  
pp. 1543-1556
Author(s):  
Navid Moslemi ◽  
Soheil Gohari ◽  
Farzin Mozafari ◽  
Mohsen Gol Zardian ◽  
Colin Burvill ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Controller Design ◽  
Compliant Mechanism ◽  
The Body ◽  
Entire Body ◽  
Knee Brace ◽  
Design Concepts ◽  
Feed Forward Controller ◽  
Actuator Design

The knee plays a significant role in locomotion and stability of the entire body through supporting the body weight and assisting the lower body kinematics during walking. However, the knee is at constant risk of becoming weakened due to disease, age, and accidents. One approach to treating weakened knee is wearing an assistive knee brace. To design a clinical knee brace, many factors such as weight and compliant mechanism should be considered. In this study, a novel smart assistive knee brace mechanism incorporated with wire actuators made of shape memory alloys is proposed to ameliorate the issues associated with weight and flexibility of existing brace designs. Unlike earlier studies, the proposed orthosis includes pressure sensor, shape memory actuator, and smart linkage. Furthermore, two distinct shape memory alloy actuator design concepts with improved stiffness are developed, and the best option is chosen systematically and prototyped. The novel mechanism proposed in this research overcomes the weight of the lower limb during swing phase using the combined shape memory alloy actuation and feed-forward controller design. As such, it can be used as a potential replacement to its conventional counterparts when the higher weight reduction as well as a flexible and controllable mechanism are simultaneously sought.

A shape memory alloy–actuated soft crawling robot based on adaptive differential friction and enhanced antagonistic configuration

2020 ◽  
Vol 31 (16) ◽  
pp. 1920-1934 ◽  
Author(s):  
Chen Liang ◽  
Yongquan Wang ◽  
Tao Yao ◽  
Botao Zhu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stride Length ◽  
Parametric Design ◽  
Thermoplastic Polyurethane ◽  
Interaction Mechanism ◽  
Experimental Tests ◽  
The Body ◽  
3D Printed ◽  
Miniature Robot

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.

Twelve Degree of Freedom Baby Humanoid Head Using Shape Memory Alloy Actuators

2011 ◽  
Vol 3 (1) ◽  
Author(s):  
Yonas Tadesse ◽  
Dennis Hong ◽  
Shashank Priya
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Kinematic Model ◽  
Complementary Metal Oxide Semiconductor ◽  
The Body ◽  
Oxide Semiconductor ◽  
Simulink Model ◽  
The Face ◽  
Nonlinear Dynamics Model ◽  
Driving Circuit

A biped mountable robotic baby head was developed using a combination of Biometal fiber and Flexinol shape memory alloy actuators (SMAs). SMAs were embedded in the skull and connected to the elastomeric skin at control points. An engineered architecture of the skull was fabricated, which incorporates all the SMA wires with 35 routine pulleys, two firewire complementary metal-oxide semiconductor cameras that serve as eyes, and a battery powered microcontroller base driving circuit with a total dimension of 140×90×110 mm3. The driving circuit was designed such that it can be easily integrated with a biped and allows programming in real-time. This 12DOF head was mounted on the body of a 21DOF miniature bipedal robot, resulting in a humanoid robot with a total of 33DOFs. Characterization results on the face and associated design issues are described, which provides a pathway for developing a humanlike facial anatomy using wire-based muscles. Numerical simulation based on SIMULINK was conducted to assess the performance of the prototypic robotic face, mainly focusing on the jaw movement. The nonlinear dynamics model along with governing equations for SMA actuators containing transcendental and switching functions was solved numerically and a generalized SIMULINK model was developed. Issues related to the integration of the robotic head with a biped are discussed using the kinematic model.

Modelling and simulation of a novel shape memory alloy actuated compliant parallel manipulator

2008 ◽  
Vol 222 (6) ◽  
pp. 1049-1059 ◽  
Author(s):  
M Sreekumar ◽  
T Nagarajan ◽  
M Singaperumal
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Compliant Mechanism ◽  
Linear Analysis ◽  
Structural Member ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Complex Behaviour ◽  
Spatial Parallel Mechanism ◽  
Simulation Results

This paper presents the non-linear analysis of a shape memory alloy (SMA) actuated fully compliant spatial parallel mechanism. A compliant mechanism made of SMA wires as its actuators and SMA pipe as its structural member that exploits both the shape memory and superelastic effects is proposed and its static analysis using ANSYS is presented in this study. Finite element analysis in a multi-physics environment considering geometric and material non-linearities helps the user to analyse complex behaviour of a system. For the proposed mechanism, simulation results show: (a) 4 per cent strain for SMA actuation is optimal considering the geometric non-linearity of the proposed mechanism for obtaining maximum displacement; (b) buckling effect is less predominant while implementing the superelastic behaviour; and (c) the mechanism can be designed as a compliant device with one or more inflexion points by exploiting the superelasticity of the SMA pipe. The knowledge obtained from the simulation study could help in further miniaturization of the manipulator.

Low-Power, Minimal-Heat Exposure Shape Memory Alloy (SMA) Actuators for On-Body Soft Robotics

2019 ◽  
Author(s):  
Simon Ozbek ◽  
Esther Foo ◽  
J. Walter Lee ◽  
Nicholas Schleif ◽  
Brad Holschuh
Keyword(s):  
Low Temperature ◽  
Shape Memory Alloy ◽  
Low Power ◽  
Shape Memory ◽  
Room Temperature ◽  
Dynamic Compression ◽  
Heat Exposure ◽  
The Body ◽  
Compression Garments ◽  
Sma Actuators

In the world of soft-robotic medical devices, there is a growing need for low profile, non-rigid, and lower power actuators for soft exoskeletons and dynamic compression garments. Advanced compression garments with integrated shape memory materials have been developed recently to alleviate the functional and usability limitations associated with traditional compression garments. These advanced garments use contractile shape memory alloy (SMA) coil actuators to produce dynamic compression on the body through selective heating of the SMA material. While these garments can create spatially- and temporally-controllable compression, typical SMA materials (e.g., 70°C Flexinol) consume considerable power and require considerable thermal insulation to protect the wearer during the heating phase of the SMA actuation. Alternative SMA materials (e.g., NiTi #8 by Fort Wayne Metals, Inc.) transform below room temperature and do so using no applied electrical power and generate no waste heat. However, these materials are challenging to dynamically control and require active refrigeration to reset to material. In theory, low-temperature SMA actuators made from materials like NiTi #8 may maintain additional dynamic actuation capacity once equilibrated to room temperature (i.e., the material may not fully transform), as the SMA phase transformation temperature window expands when the material experiences applied stress. This paper investigates this possibility: we manufactured and tested low-temperature NiTi coil actuators to determine the magnitude of the additional force that can be generated via Joule heating once the material has equilibrated to room temperature. SMA spring actuators made from NiTi #8 consumed 84% less power and stabilized at significantly lower temperatures (26.0°C vs. 41.2°C) than SMA springs made from 70°C Flexinol, when actuated at identically fixed displacements (100% nominal strain) and when driven to produce equal forces (∼3.35N). This demonstration of low-power, minimal-heat exposure SMA actuation holds promise for many future wearable actuation applications, including dynamic compression garments.

scholarly journals Route to Chaos and Bistability Analysis of Quasi-Periodically Excited Three-Leg Supporter with Shape Memory Alloy

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Manisekaran Varadharajan ◽  
Prakash Duraisamy ◽  
Anitha Karthikeyan
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Controller Design ◽  
Initial Conditions ◽  
Basin Of Attraction ◽  
Martensite Phase ◽  
Dynamical Response ◽  
Periodic Excitation ◽  
Strange Nonchaotic Attractors ◽  
Parameter Ranges

In this paper, the effect of quasi-periodic excitation on a three-leg supporter configured with shape memory alloy is investigated. We derived the equation of motion for the system using the supporter configuration and polynomial constitutive model of the shape memory alloys (SMAs) based on Falk model. Two sets of parameters and symmetric initial conditions are used to analyze the system. The system responded with a chaotic attractor and a strange nonchaotic attractor. Coexistence of these attractors is studied and discussed with corresponding phase portrait, bifurcation plot, and cross section of basin of attraction. We confirm the quasi-periodic excitation results with generation of strange nonchaotic attractors as discussed in the literature. The special properties like symmetricity and bistability are revealed and the parameter ranges of existence of such behaviors are discussed. The system is analyzed for different phases and the existence of bistability in martensite phase and transition phase is explained. While the system enters into austenite phase, the bistability behavior vanishes. The results provide insight knowledge into dynamical response of a quasi-periodically excited SMA leg support system and will be useful for design improvements and controller design.

Smart wing shape memory alloy actuator design and performance

1997 ◽  
Author(s):  
A. Peter Jardine ◽  
John S. Flanagan ◽  
Christopher A. Martin ◽  
Bernie F. Carpenter
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Wing Shape ◽  
Shape Memory Alloy Actuator ◽  
And Performance ◽  
Actuator Design

Effect of Geometric Design Parameters on Contractile SMA Knitted Actuator Performance

2017 ◽  
Author(s):  
Kevin Eschen ◽  
Julianna Abel
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Load Capacity ◽  
Design Parameters ◽  
Partial Recovery ◽  
Thermal Actuation ◽  
The Wire ◽  
High Level ◽  
Actuator Design ◽  
Actuator Performance

Shape memory alloy (SMA) knitted actuators are a type of functional fabric that uses shape memory alloy wire as an active fiber within a knitted textile. Through intentional design of the SMA knitted actuator geometry, various two- and three-dimensional actuation motions, such as scrolling and contraction [1], can be accomplished. Contractile SMA knitted actuators leverage the unique thermo-mechanical properties of SMA wires by integrating them within the hierarchical knitted structure to achieve large distributed uniaxial contractions and variable stiffness behavior upon thermal actuation. During the knit manufacturing process, the SMA wire is bent into a network of interlacing adjacent loops, storing potential energy within the contractile SMA knitted actuator. Thermal actuation above the wire-specific austenite finish temperature leads to a partial recovery of the bending deformations, resulting in large distributed uniaxial contraction (15–40% actuation contraction observed) of the SMA knitted actuator. The achievable load capacity and %-actuation contraction are dependent on the geometric loop parameters of the contractile SMA knitted actuator. While exact descriptions of the geometric loop parameters exist, a reduction of the geometric complexity is advantageous for high-level contractile SMA knitted actuator design procedures. This paper defines a simple geometric measure, the non-dimensional knit density, and experimentally correlates the contractile SMA knitted actuator performance to this measure. The experimentally demonstrated dependency of relevant actuator metrics on the knit density and the wire diameter, suggests the usability of the simplified geometry definition for a high-level contractile SMA knitted actuator design.

scholarly journals Shape Memory Alloy Actuator Design: CASMART Collaborative Best Practices

2011 ◽  
Author(s):  
Othmane Benafan ◽  
Jeff Brown ◽  
F. Tad Calkins ◽  
Parikshith Kumar ◽  
Aaron Stebner ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Best Practices ◽  
Shape Memory ◽  
System Design ◽  
System Integration ◽  
Working Group ◽  
Shape Memory Alloy Actuator ◽  
Wide Range ◽  
Actuator Design ◽  
Single Medium

Upon examination of shape memory alloy (SMA) actuation designs, there are many considerations and methodologies that are common to them all. A goal of CASMART’s design working group is to compile the collective experiences of CASMART’s member organizations into a single medium that engineers can then use to make the best decisions regarding SMA system design. In this paper, a review of recent work toward this goal is presented, spanning a wide range of design aspects including evaluation, properties, testing, modeling, alloy selection, fabrication, actuator processing, design optimization, controls, and system integration. We have documented each aspect, based on our collective experiences, so that the design engineer may access the tools and information needed to successfully design and develop SMA systems. Through comparison of several case studies, it is shown that there is not an obvious single, linear route a designer can adopt to navigate the path of concept to product. SMA engineering aspects will have different priorities and emphasis for different applications.

Sign in / Sign up

Export Citation Format

Share Document