A Soft Robotic Model to Study the Effects of Stiffness on Fish-Like Undulatory Swimming

Wolf, Zane; Lauder, George V.

doi:10.1007/978-3-030-50476-2_8

Cited by 2 publications

(8 citation statements)

References 38 publications

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“…In our study, however, as we are not controlling it to remain constant, the tail swing amplitude tends to decrease as frequency increases, as shown in Figure 3 and 4. This phenomenon is related to the water resistance as well as the actuator and caudal fin stiffness, and it agrees with the results obtained by Wolf & Lauder (2021) in Figure 8 4.B…”

Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 82%

“…The robot’s self-propelled swimming speed for a given combination of parameters is estimated by measuring the forward thrust at various flow speeds. Figure 5 shows a reduction of the forward thrust as the flow speed increases, similar to the results obtained by Wolf & Lauder (2021) in Figure 8 4.C…”

Section: Resultssupporting

confidence: 82%

“…The stiffness of the swimming platform is not constant throughout its length; in fact, only the anterior part is actuated, while the posterior is a flexible passive foil. This particular mechanical structure allows the creation of different oscillating modes in the undulating tail, as can be seen in Figure 3 and Figure 4, similar to the results obtained by Wolf & Lauder (2021) in Figure 8.3.C. The presence of oscillating modes in Figure 3 and Figure 4 alters the thrust generation while the robotic platform is actuated, as already hypothesized by Jusufi et al (2017) in Figure 5, where a peak in thrust generation appears with an oscillating frequency of 0.55 Hz.…”

Section: Limitation Of Studysupporting

confidence: 84%

“…The soft robotic fish-shaped marine reptile used in this work is presented in Figure 2. It consists of a flexible foil, representing the backbone, to which two soft pneumatic actuators are glued to provide bending actuation (Wolf & Lauder 2021). A frontal 3D-printed ABS cuff serves as an attachment point for the force/torque (F/T) sensing equipment (ATI nano17), while another 3D-printed, flexible, TPU A95 tail cuff allows the attachment and detachment of caudal fins for tests with different shapes.…”

Section: Soft Active Materials Physical Modelmentioning

confidence: 99%

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Asymmetric Fin Shape changes Swimming Dynamics of Ancient Marine Reptiles’ Soft Robophysical Models

Sprumont,

Allione,

Schwab

et al. 2024

Preprint

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Animals have evolved highly effective locomotion capabilities in terrestrial, aerial, and aquatic environments. Over life’s history, mass extinctions have wiped out unique animal species with specialized adaptations, leaving paleontologists to reconstruct their locomotion through fossil analysis. Despite advancements, little is known about how extinct megafauna, such as the Triassic ichthyosaurMixosaurus cornalianus, one of the most successful lineages of marine reptiles, utilized their varied morphologies for swimming. Traditional robotics struggle to mimic extinct locomotion effectively, but the emerging soft robotics field offers a promising alternative to overcome this challenge. This paper aims to bridge this gap by studyingMixosauruslocomotion with soft robotics, combining material modeling and biomechanics in physical experimental validation. Combining a soft body with soft pneumatic actuators, the soft robotic platform described in this study investigates the correlation between asymmetrical fins and buoyancy by recreating the pitch torque generated by extinct swimming animals. We performed a comparative analysis of thrust and torque generated byCarthorhyncus, Utatsusaurus, Mixosaurus, Guizhouichthyosaurus, andOphthalmosaurustail fins in a flow tank. Experimental results suggest that the pitch torque on the torso generated by hypocercal fin shapes such as found in model systems ofGuizhouichthyosaurus, MixosaurusandUtatsusaurusproduce distinct ventral body pitch effects able to mitigate the animal’s non-neutral buoyancy. This body pitch control effect is particularly pronounced inGuizhouichthyosaurus, which results suggest would have been able to generate high ventral pitch torque on the torso to compensate for its positive buoyancy. By contrast, homocercal fin shapes may not have been conducive for such buoyancy compensation, leaving torso pitch control to pectoral fins, for example. Across the range of the actuation frequencies of the caudal fins tested, resulted in oscillatory modes arising, which in turn can affect the for-aft thrust generated.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 82%

Section: Resultssupporting

confidence: 82%

Section: Limitation Of Studysupporting

confidence: 84%

Section: Soft Active Materials Physical Modelmentioning

confidence: 99%

See 3 more Smart Citations

Asymmetric Fin Shape changes Swimming Dynamics of Ancient Marine Reptiles’ Soft Robophysical Models

Sprumont,

Allione,

Schwab

et al. 2024

Preprint

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Gradients of properties increase the morphing and stiffening performance of bioinspired synthetic fin rays

Das,

Kunjam,

Ebeling

et al. 2024

Bioinspir. Biomim.

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State-of-the-art morphing materials are either very compliant to achieve large shape changes (flexible metamaterials, compliant mechanisms, hydrogels), or very stiff but with infinitesimal changes in shape that require large actuation forces (metallic or composite panels with piezoelectric actuation). Morphing efficiency and structural stiffness are therefore mutually exclusive properties in current engineering morphing materials, which limits the range of their applicability. Interestingly, natural fish fins do not contain muscles, yet they can morph to large amplitudes with minimal muscular actuation forces from the base while producing large hydrodynamic forces without collapsing. This sophisticated mechanical response has already inspired several synthetic fin rays with various applications. However, most “synthetic” fin rays have only considered uniform properties and structures along the rays while in natural fin rays, gradients of properties are prominent. In this study, we designed, modeled, fabricated and tested synthetic fin rays with bioinspired gradients of properties. The rays were composed of two hemitrichs made of a stiff polymer, joined by a much softer core region made of elastomeric ligaments. Using combinations of experiments and nonlinear mechanical models, we found that gradients in both the core region and hemitrichs can increase the morphing and stiffening response of individual rays. Introducing a positive gradient of ligament density in the core region (the density of ligament increases towards the tip of the ray) decreased the actuation force required for morphing and increased overall flexural stiffness. Introducing a gradient of property in the hemitrichs, by tapering them, produced morphing deformations that were distributed over long distances along the length of the ray. These new insights on the interplay between material architecture and properties in nonlinear regimes of deformation can improve the designs of morphing structures that combine high morphing efficiency and high stiffness from external forces, with potential applications in aerospace or robotics.

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A Soft Robotic Model to Study the Effects of Stiffness on Fish-Like Undulatory Swimming

Cited by 2 publications

References 38 publications

Asymmetric Fin Shape changes Swimming Dynamics of Ancient Marine Reptiles’ Soft Robophysical Models

Asymmetric Fin Shape changes Swimming Dynamics of Ancient Marine Reptiles’ Soft Robophysical Models

Gradients of properties increase the morphing and stiffening performance of bioinspired synthetic fin rays

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