Variable Stiffness Linear Actuator Based on Differential Drive Fiber Jamming

Arleo, Luca; Lorenzon, Lucrezia; Cianchetti, Matteo

doi:10.1109/tro.2023.3236941

Cited by 12 publications

(15 citation statements)

References 35 publications

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“…The deformable coil was inflated with incremental pressure p to generate ribs of variable W r and H r depending on N r , and N l . In particular, according to basic mechanics considerations and the results obtained in [23], an increase in stiffness is expected for higher N l , whereas the influence of N r cannot be predicted in advance. Indeed, increasing its value from one side brings to a reduction of H r , and therefore in the second moment of inertia of the single rib.…”

Section: Design and Geometrymentioning

confidence: 94%

“…In addition, the variation of p increases the friction among the layers of the external membrane and reduces their sliding motion. In our preliminary study [23], we demonstrated that the creation of multiple ribs through an increase of pressure allowed to significantly raise the stiffness of the structure without compromising its compact, lightweight, and easy-to-manufacture characteristics. That study showed how the system can reach remarkable values of R, passing from a very compliant to a stiff state.…”

Section: Introductionmentioning

confidence: 92%

“…However, this is true under the assumption of small displacements applied, in which the layers of the two sides act as single blocks (pre-slip state). In the post-slip state, layers start to slide and the stiffness of jamming devices is highly influenced by the dynamic friction [11,21]. Therefore, increasing p the stiffness in the post-slip state is affected, resulting in a variation of the overall performances.…”

Section: Design and Geometrymentioning

confidence: 99%

“…This parameter is mainly influenced by the filler material. LJ and CMJ (R up to 70 [12]) perform better than GJ (R up to 5 [3]), while FJ assumes inbetween values (R up to 21 [21]). Some of these categories were recently combined to increase the variable stiffness performances.…”

Section: Introductionmentioning

confidence: 97%

“…In light of the promising results shown in this work, we extended the hybrid approach in applications where planar shapes are required. In a preliminary work [23], we introduced a planar bioinspired variable stiffness structure. As in the referenced study [22], we harnessed the inherent shape variation to augment the stiffness of the structures.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Variable stiffness structure inspired by seashells

Pagliarani,

Arleo,

Luca

et al. 2024

Smart Mater. Struct.

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Variable stiffness is typically employed in soft robotics to address the trade-off between compliance and the ability to generate stability when required. Among the several approaches investigated, jamming transition systems show remarkable stiffness performance and fast response. Building upon the preliminary study on a seashell bioinspired variable stiffness structure, here we extend the design space through a parametric study supported by a finite element model based on commercially available software. The study allows establishing the relationship between the design parameters and the stiffness performance. Moreover, the optimal configuration in terms of performance to energy consumption is identified and compared to previous similar approaches. Finally, the low computational cost of the finite element model demonstrated to be an effective tool for the analysis of complex geometries, thereby establishing a foundation for the development of cost-effective and lightweight soft robotic devices empowered by variable stiffness capabilities (e.g. a wearable device for assistance)

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Section: Design and Geometrymentioning

confidence: 94%

Section: Introductionmentioning

confidence: 92%

Section: Design and Geometrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Variable stiffness structure inspired by seashells

Pagliarani,

Arleo,

Luca

et al. 2024

Smart Mater. Struct.

Self Cite

View full text Add to dashboard Cite

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FlexiStiff: A Variable Tensile Stiffness Element for Modulating the Behavior of Tensegrity Structures

Arshad,

Jamil,

Rodrigue

2024

Adv Eng Mater

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Soft and tensegrity structures are two configurations that have appeared as robots continue to draw inspiration from nature and diversify beyond rigid machines toward compliant systems. One artificial manifestation of a biological attribute that is an active research topic is the body's capacity to calibrate its stiffness for adapting its behavior to a given task. This study brings together these designs spaces and presents a soft tensile element named FlexiStiff for tensegrity structures to enable transitioning between flexible and stiff states for variable load‐bearing capability and compliance. The device's tensile stiffness constant can be increased by 4400% with a change in pressure. It can provide a high blocking force of 535.5 N and can endure elongation up to 184%. It is assembled using four commercially available materials and a two‐step fabrication method consisting of 3D printing and elastomer curing. As opposed to classical tensegrities for which shape change is inexpensive in terms of energy, this work betokens a new stage in their design wherein the arrangement can radically alter the magnitude of its demand for external energy for shape morphing, a crucial characteristic for operation in partially mapped environments that present diverse terrains and disturbances of varying intensities prompting adaptability.

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Layer Jamming of Magnetorheological Elastomers for Variable Stiffness in Soft Robots

Atakuru,

Züngör,

Samur

2024

Exp Mech

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Background One of the biggest challenges in soft robotics is the variability and controllability of stiffness. Jamming-based approaches have been of interest to change stiffness dramatically by increasing friction between grains, layers, or fibers. Besides, magnetorheological elastomers (MREs) that exhibit magnetic field-dependent viscoelasticity have significant potential as a stiffness variation material. This study investigates the unique mechanics of magnetic jamming of MRE sheets exploring stiffness change both due to jamming and variable viscosity. Methods Sample MREs and flexible neodymium-iron-boron (NdFeB) magnets are manufactured. Uniaxial tensile tests supported with digital image correlation are performed to characterize the materials. Multi-layer jamming structures comprised of MREs and NdFeB magnets are developed and validated through 3-point bending experiments and finite element simulations. Results Results show that the stiffness of the multi-layer structure is higher under magnetic field. Furthermore, the stiffness change is increased when MREs are used instead of PDMS as layers. Conclusion This study proves the concept of magnetic jamming of MRE layers. The results are crucial for the possible soft robotic implementation of the proposed hybrid stiffening approach combining jamming with viscoelasticity modification.

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Variable Stiffness Linear Actuator Based on Differential Drive Fiber Jamming

Cited by 12 publications

References 35 publications

Variable stiffness structure inspired by seashells

Variable stiffness structure inspired by seashells

FlexiStiff: A Variable Tensile Stiffness Element for Modulating the Behavior of Tensegrity Structures

Layer Jamming of Magnetorheological Elastomers for Variable Stiffness in Soft Robots

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