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

2019 ◽  
Vol 9 (19) ◽  
pp. 4025 ◽  
Author(s):  
Jaeyeon Jeong ◽  
Ibrahim Bin Yasir ◽  
Jungwoo Han ◽  
Cheol Hoon Park ◽  
Soo-Kyung Bok ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Wrist Flexion ◽  
Wearable Robot ◽  
Maximum Torque ◽  
Wrist Motion ◽  
Contraction Ratio ◽  
Flexion Extension ◽  
The Average Range

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.

Helical Kirigami-Enabled Centimeter-Scale Worm Robot With Shape-Memory-Alloy Linear Actuators

2015 ◽  
Vol 7 (2) ◽  
Author(s):  
Ketao Zhang ◽  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Kinematic Model ◽  
Parallel Structure ◽  
Geometrical Parameters ◽  
Parallel Structures ◽  
Complete Procedure ◽  
Motion Characteristics

The wormlike robots are capable of imitating amazing locomotion of slim creatures. This paper presents a novel centimeter-scale worm robot inspired by a kirigami parallel structure with helical motion. The motion characteristics of the kirigami structure are unravelled by analyzing the equivalent kinematic model in terms of screw theory. This reveals that the kirigami parallel structure with three degrees-of-freedom (DOF) motion is capable of implementing both peristalsis and inchworm-type motion. In light of the revealed motion characteristics, a segmented worm robot which is able to imitate contracting motion, bending motion of omega shape and twisting motion in nature is proposed by integrating kirigami parallel structures successively. Following the kinematic and static characteristics of the kirigami structure, actuation models are explored by employing the linear shape-memory-alloy (SMA) coil springs and the complete procedure for determining the geometrical parameters of the SMA coil springs. Actuation phases for the actuation model with two SMA springs are enumerated and with four SMA springs are calculated based on the Burnside's lemma. In this paper, a prototype of the worm robot with three segments is presented together with a paper-made body structure and integrated SMA coil springs. This centimeter-scale prototype of the worm robot is lightweight and can be used in confined environments for detection and inspection. The study presents an interesting approach of integrating SMA actuators in kirigami-enabled parallel structures for the development of compliant and miniaturized robots.

Prediction of Ligament Length During Wrist Flexion Extension

2008 ◽  
Author(s):  
Rita M. Patterson ◽  
Naoya Yazaki ◽  
Clark R. Andersen ◽  
Newt H. Scott ◽  
Steven F. Viegas
Keyword(s):  
Direct Measurement ◽  
High Precision ◽  
Carpal Bones ◽  
Short Length ◽  
Ligament Length ◽  
Wrist Flexion ◽  
Wrist Motion ◽  
Flexion Extension ◽  
Carpal Ligaments ◽  
Precision Motion

Direct measurement of ligament length in the wrist is difficult due to constrained space and short length of many ligaments. No prior studies have reported measurements of ligament length between the carpal bones of the wrist. In this presentation, we have combined high precision motion analysis of the carpal bones, subsequent manual digitization of the ligament attachment regions, and a simulated ligament wrapping model, to generate predictions of carpal ligaments’ length and implied strain during wrist motion.

DYNAMIC MODELING AND EVALUATION OF A ROBOTIC EXOSKELETON FOR UPPER-LIMB REHABILITATION

2011 ◽  
Vol 08 (01) ◽  
pp. 83-102 ◽  
Author(s):  
MOHAMMAD HABIBUR RAHMAN ◽  
THIERRY KITTEL-OUIMET ◽  
MAAROUF SAAD ◽  
JEAN-PIERRE KENNÉ ◽  
PHILIPPE S. ARCHAMBAULT
Keyword(s):  
Dynamic Modeling ◽  
Upper Limb ◽  
Degrees Of Freedom ◽  
Vital Role ◽  
Torque Control ◽  
Control Technique ◽  
Wrist Flexion ◽  
Upper Limb Rehabilitation ◽  
Flexion Extension ◽  
Physically Disabled People

Proper functioning of the shoulder, elbow, and wrist movements play a vital role in the performance of essential daily activities. To assist physically disabled people with impaired upper-limb function, we have been developing an exoskeleton robot (ExoRob) to rehabilitate and to ease upper limb motion. The proposed ExoRob will be comprised of seven degrees of freedom (DOFs) to enable natural movements of the human upper-limb. This paper focuses on the kinematic and dynamic modeling of the proposed ExoRob that corresponds to human upper-limbs. For this purpose, a nonlinear computed torque control technique was employed. In simulations, trajectory tracking corresponding to typical rehabilitation exercises were carried out to evaluate the performances of the developed model and controller. For the experimental part, only 3DOFs (elbow, wrist flexion/extension, wrist abduction/adduction) were considered. Simulated and experimental results show that the controller was able to maneuver the proposed ExoRob efficiently in order to track the desired trajectories, which in this case consisted in passive arm movements. Such movements are widely used in therapy and were performed efficiently with the developed ExoRob and the controller.

scholarly journals Carpal Pronation and Supination Changes in the Unstable Wrist

2018 ◽  
Vol 07 (04) ◽  
pp. 298-302
Author(s):  
Walter Short ◽  
Frederick Werner
Keyword(s):  
Clinical Relevance ◽  
Wrist Flexion ◽  
New Techniques ◽  
Interosseous Ligament ◽  
Wrist Motion ◽  
Extensor Carpi Ulnaris ◽  
Flexion Extension ◽  
Before And After ◽  
Dart Throwing ◽  
Throwing Motion

Background Little is known about changes in scaphoid and lunate supination and pronation following scapholunate interosseous ligament (SLIL) injury. Information on these changes may help explain why some SLIL reconstructions have failed and help in the development of new techniques. Purpose To determine if following simulated SLIL injury there was an increase in scaphoid pronation and lunate supination and to determine if concurrently there was an increase in the extensor carpi ulnaris (ECU) force. Materials and Methods Scaphoid and lunate motion were measured before and after sectioning of the SLIL and two volar ligaments in 22 cadaver wrists, and before and after sectioning of the SLIL and two dorsal ligaments in 15 additional wrists. Each wrist was dynamically moved through wrist flexion/extension, radioulnar deviation, and a dart-throwing motion. Changes in the ECU force were recorded during each wrist motion. Results Scaphoid pronation and lunate supination significantly increased following ligamentous sectioning during each motion. There were significant differences in the amount of change in lunate motion, but not in scaphoid motion, between the two groups of sectioned ligaments. Greater percentage ECU force was required following ligamentous sectioning to achieve the same wrist motions. Conclusion Carpal supination/pronation changed with simulated damage to the scapholunate stabilizers. This may be associated with the required increases in the ECU force. Clinical Relevance In reconstructing the SLIL, one should be aware of the possible need to correct scaphoid pronation and lunate supination that occur following injury. This may be more of a concern when the dorsal stabilizers are injured.

Self-Folding Origami Using Torsion Shape Memory Alloy Wire Actuators

2014 ◽  
Author(s):  
Je-sung Koh ◽  
Sa-reum Kim ◽  
Kyu-jin Cho
Keyword(s):  
Form Factor ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Shape Memory Alloy Wire ◽  
Maximum Torque ◽  
Alloy Wire ◽  
Low Profile ◽  
The Wire ◽  
Linear Manner ◽  
Novel Design

Self-folding origami requires a low-profile actuator to be embedded in a sheet of paper-like planar material. Various actuation methods have been employed to actively fold such sheets. This paper presents a torsion shape-memory alloy (SMA) wire actuator embedded in patterned origami structures that actively folds the origami by twisting the SMA wire. A simple wire is aligned with the fold line, and each end is fixed to a facet. The twisting of the wire directly rotates the facets. This method has the advantage of using an easily available wire SMA and the advantage of a flat form factor similar to that of sheet SMA. Generally, SMA wire is used in a linear manner or as a spring. The torsion SMA wire presented in this paper is trained to generate torsional force when heated. The amount of rotation depends on the length of the wire; a 200-μm-diameter SMA wire 12 mm in length can induce 540° rotation. SMA wires are arranged in pairs side by side to rotate the facets in both directions. Maximum torque of 70 mNcm is generated in this antagonistic arrangement. The torsion SMA wire actuators enable a novel design for a programmable folding sheet that is easily manufactured and exhibits fast folding and unfolding.

Development of a Proof-of-Concept Aircraft Smart Control System

2009 ◽  
Author(s):  
Parsaoran Hutapea
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Flight Control ◽  
Degrees Of Freedom ◽  
Cooling System ◽  
Control Mechanisms ◽  
Proof Of Concept ◽  
Concept Model ◽  
Actuation System ◽  
Smart Control

Hutapea et al (Aircraft Engineering and Aerospace Technology: 80(4), 439–444, 2008) proposed an actuation system based on shape memory alloy springs for a wing flap of an aircraft. A continued research and development of these previously demonstrated smart flight control mechanisms was performed with the goal to develop a proof-of-concept shape memory alloy (SMA) actuation system, which utilizes SMA springs to control the six degrees of freedom of an aircraft. As a significant advancement to the overall actuation system, an air burst-cooling system was added to increase the cooling rate of the SMA springs by means of forced convection. A one-sixth scale proof-of-concept model was constructed to demonstrate and to verify the final actuation system design.

A shape memory alloy-based tendon-driven actuation system for biomimetic artificial fingers, part I: design and evaluation

Robotica ◽  
2009 ◽  
Vol 27 (1) ◽  
pp. 131-146 ◽  
Author(s):  
Vishalini Bundhoo ◽  
Edmund Haslam ◽  
Benjamin Birch ◽  
Edward J. Park
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Ad Hoc ◽  
Controller Design ◽  
Artificial Muscle ◽  
Robotic Hand ◽  
Pulse Width Modulated ◽  
Actuation System ◽  
Minimum Jerk ◽  
Flexion Extension

SUMMARYIn this paper, a new biomimetic tendon-driven actuation system for prosthetic and wearable robotic hand applications is presented. It is based on the combination of compliant tendon cables and one-way shape memory alloy (SMA) wires that form a set of agonist–antagonist artificial muscle pairs for the required flexion/extension or abduction/adduction of the finger joints. The performance of the proposed actuation system is demonstrated using a 4 degree-of-freedom (three active and one passive) artificial finger testbed, also developed based on a biomimetic design approach. A microcontroller-based pulse-width-modulated proportional-derivation (PWM-PD) feedback controller and a minimum jerk trajectory feedforward controller are implemented and tested in anad hocfashion to evaluate the performance of the finger system in emulating natural joint motions. Part II describes the dynamic modeling of the above nonlinear system, and the model-based controller design.

Analysis of Shape Memory Alloy Components Using Beam, Shell, and Continuum Finite Elements

2010 ◽  
Author(s):  
Darren Hartl ◽  
Tyler Zimmerman ◽  
Matthew Dilligan ◽  
James Mabe ◽  
Frederick Calkins
Keyword(s):  
Finite Elements ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Constitutive Models ◽  
Analysis Tool ◽  
Three Dimensional Model ◽  
Restoring Force ◽  
Element Analysis

This work discusses the increased capabilities of a three-dimensional analysis tool for shape memory alloy engineering components. As the number and complexity of proposed SMA applications increases, engineers and designers must seek out or develop more capable predictive methods. Three-dimensional models implemented in a continuum finite element analysis (FEA) framework can be applied to most SMA component geometries. However, such methods may require fine meshes in 3-D space, resulting in many degrees of freedom and potentially long analysis times. On the other hand, constitutive models implemented in one dimension can be simple and fast, but are restricted to a limited class of problems for which such reductions are appropriate (e.g., rods and beams). More recently, engineers have begun investigating more complex SMA bending components for which 2-D shell elements might provide a computationally efficient FEA discretization. Here we consider a single modeling tool (a material subroutine) that combines 1-D, 2-D, and 3-D implementations for use in a general FEA framework. As an example analysis case, we consider an SMA bending element that has been adhesively bonded to a carbon fiber-reinforced polymer (CFRP) laminate and is subjected to thermally-induced actuation. The active SMA and passive composite components are bonded in a pre-stressed configuration such that the elastic laminate provides a variable restoring force to the SMA during transformation, resulting in repeatable actuation cycles. This two-part bonded configuration is analyzed using different types of finite elements (1-D beam, 2-D shell, and full 3-D continuum elements). The constitutive behavior of the shape memory alloy is defined using an established three-dimensional model based on continuum thermodynamics and motivated by the methods of classical plasticity. A user material subroutine (UMAT) in an Abaqus Unified FEA framework is used to implement the model. The methodology for capturing 1-D, 2-D, and 3-D thermomechanical response in a single such UMAT is described. The run times of the various analyses are compared, and the relative accuracies of the results are discussed.

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