Soft, Multi-DoF, Variable Stiffness Mechanism Using Layer Jamming for Wearable Robots

Choi, Won Ho; Kim, Sunghwan; Lee, Dongun; Shin, Dong-Chun

doi:10.1109/lra.2019.2908493

Cited by 67 publications

(39 citation statements)

References 24 publications

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“…Jamming structures and their ability to provide different forms of variable impedance have led to many robotics applications. [ 7–19,27–51 ] Yet prior work does not provide a framework to allow engineers and designers to manage performance‐based trade‐offs when designing jamming structures for applications. In this section, we first outline the fundamental behavior of grains, layers, and fibers as observed in their leading applications in robotics.…”

Section: Resultsmentioning

confidence: 99%

“…Interlocking geometries can be utilized to create kinematic constraints to only allow for motion in particular directions. [ 31–35,53–57 ] Fibers can have prismatic cross sections, rather than circular ones to avoid kinematic rearrangement in particular directions and to transform the contact lines between constituents into contact surfaces. [ 14 ] Particles can be designed with particular geometries to create larger number of contact points, or larger contact surface areas between the particles.…”

Section: Resultsmentioning

confidence: 99%

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A Modeling Framework for Jamming Structures

Aktaş

Narang

Vasios

et al. 2021

Adv Funct Materials

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Jamming is a structural phenomenon that provides tunable mechanical behavior. A jamming structure typically consists of a collection of elements with low effective stiffness and damping. When a pressure gradient, such as vacuum, is applied, kinematic and frictional coupling increase, resulting in dramatically altered mechanical properties. Engineers have used jamming to build devices from tunable‐stiffness grippers to tunable‐damping landing gear. This study presents a rigorous framework that systematically guides the design of jamming structures for target applications. The force‐deflection behavior of major types of jamming structures (i.e., grain, fiber, and layer) in fundamental loading conditions (e.g., tension, shear, and bending) is compared. High‐performing pairs (e.g., grains in compression, layers in shear, and bending) are identified. Parameters that go into designing, fabricating, and actuating a jamming structure (e.g., scale, material, geometry, and actuator) are described, along with their effects on functional metrics. Two key methods to expand on the design space of jamming structures are introduced: using structural design to achieve effective tunable‐impedance behavior in specific loading directions, and creating hybrid jamming structures to utilize the advantages of different types of jamming. Collectively, this study elaborates and extends the jamming design space, providing a conceptual modeling framework for jamming‐based structures.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A Modeling Framework for Jamming Structures

Aktaş

Narang

Vasios

et al. 2021

Adv Funct Materials

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show abstract

“…They can be fabricated entirely using a 3D printing technique. Choi et al [ 90 ] proposed that these structures can be used to develop the spinal assistance robot and in various other wearable applications.…”

Section: Advancement In Spinal Rehabilitation Orthosesmentioning

confidence: 99%

Spinal Deformities and Advancement in Corrective Orthoses

et al. 2020

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Spinal deformity is an abnormality in the spinal curves and can seriously affect the activities of daily life. The conventional way to treat spinal deformities, such as scoliosis, kyphosis, and spondylolisthesis, is to use spinal orthoses (braces). Braces have been used for centuries to apply corrective forces to the spine to treat spinal deformities or to stabilize the spine during postoperative rehabilitation. Braces have not modernized with advancements in technology, and very few braces are equipped with smart sensory design and active actuation. There is a need to enable the orthotists, ergonomics practitioners, and developers to incorporate new technologies into the passive field of bracing. This article presents a review of the conventional passive braces and highlights the advancements in spinal orthoses in terms of improved sensory designs, active actuation mechanisms, and new construction methods (CAD/CAM, three-dimensional (3D) printing). This review includes 26 spinal orthoses, comprised of passive rigid/soft braces, active dynamics braces, and torso training devices for the rehabilitation of the spine.

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“…According to the realization principle of variable stiffness, wearable robots can be classified into three types: functional material-based [11][12][13][14][15][16][17][18], vacuum-based [19][20][21][22][23][24][25][26][27], and friction-based [28][29][30]. In particular, functional material-based type robots have obvious advantages in terms of volume and weight, and a shape memory alloy (SMA) is the most frequently employed functional material in the variable stiffness structure design [11,12].…”

Section: Introductionmentioning

confidence: 99%

Friction Prediction and Validation of a Variable Stiffness Lower Limb Exosuit Based on Finite Element Analysis

Zuo

Chen

et al. 2021

Actuators

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The variable stiffness exosuit has great potential for human augmentation and medical applications. However, the model of the variable stiffness mechanism in exosuits is far from satisfactory for the accurate prediction and control of friction force. This paper presents a friction prediction model of a variable stiffness lower limb exosuit, verifies its prediction performance, and identifies its applicability. The friction force model was established by the Coulomb friction hypothesis. The equivalent coefficient, which is the core parameter of the model, was determined based on friction and squeezing force data obtained by tests and an ANSYS simulation. Experiments show that the prediction error of the proposed model can reach 15% with a proper structural dimension change constraint. The friction force control test showed that the achieved model can shorten the settling time of the step response by 26% and eliminate the steady-state error. Verifications indicate that the proposed method can provide guidance to the modeling of other friction/stiffness structures, especially friction-based wearable robot structure models and predictions.

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Soft, Multi-DoF, Variable Stiffness Mechanism Using Layer Jamming for Wearable Robots

Cited by 67 publications

References 24 publications

A Modeling Framework for Jamming Structures

A Modeling Framework for Jamming Structures

Spinal Deformities and Advancement in Corrective Orthoses

Friction Prediction and Validation of a Variable Stiffness Lower Limb Exosuit Based on Finite Element Analysis

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