Frequency tuning in animal locomotion

Ahlborn, B.; Blake, Robert W.; Megill, William

doi:10.1016/j.zool.2005.11.001

Cited by 42 publications

(48 citation statements)

References 27 publications

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“…Because the tail oscillation exploits resonance, the body adjusts its stiffness, so that the resonance frequency matches the frequency required to achieve a desired speed. This result agrees with the frequency tuning theory observed in animals [4,7,41]. The model analytically predicts that optimal tail-beat frequency v and tail stiffness K are proportional to v and v 2 , respectively, and the optimal tail-beat amplitude stays constant over a range of swimming speeds.…”

Section: Resonance Mechanisms Underlying Swimmingsupporting

confidence: 89%

Analytical insights into optimality and resonance in fish swimming

Kohannim

Iwasaki

2014

J. R. Soc. Interface.

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This paper provides analytical insights into the hypothesis that fish exploit resonance to reduce the mechanical cost of swimming. A simple body-fluid fish model, representing carangiform locomotion, is developed. Steady swimming at various speeds is analysed using optimal gait theory by minimizing bending moment over tail movements and stiffness, and the results are shown to match with data from observed swimming. Our analysis indicates the following: thrust-drag balance leads to the Strouhal number being predetermined based on the drag coefficient and the ratio of wetted body area to cross-sectional area of accelerated fluid. Muscle tension is reduced when undulation frequency matches resonance frequency, which maximizes the ratio of tail-tip velocity to bending moment. Finally, hydrodynamic resonance determines tail-beat frequency, whereas muscle stiffness is actively adjusted, so that overall body-fluid resonance is exploited.

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Section: Resonance Mechanisms Underlying Swimmingsupporting

confidence: 89%

Analytical insights into optimality and resonance in fish swimming

Kohannim

Iwasaki

2014

J. R. Soc. Interface.

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“…Explanations for this constraint given in the literature include selective pressure for propulsive efficiency, the resonant frequency of the musculature, and stability modes of the time-averaged wake (e.g., Alborn et al 2006;Fish & Lauder 2006, and references therein; Triantafyllou et al 2000). Let us now consider the possibility that the Strouhal frequency constraint is primarily a consequence of the process of optimal vortex formation.…”

Section: Indirect Studies Of Optimal Vortex Formation: Strouhal Frequmentioning

confidence: 99%

Optimal Vortex Formation as a Unifying Principle in Biological Propulsion

Dabiri

2009

Annu. Rev. Fluid Mech.

273

171

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I review the concept of optimal vortex formation and examine its relevance to propulsion in biological and bio-inspired systems, ranging from the human heart to underwater vehicles. By using examples from the existing literature and new analyses, I show that optimal vortex formation can potentially serve as a unifying principle to understand the diversity of solutions used to achieve propulsion in nature. Additionally, optimal vortex formation can provide a framework in which to design engineered propulsions systems that are constrained by pressures unrelated to biology. Finally, I analyze the relationship between optimal vortex formation and previously observed constraints on Strouhal frequency during animal locomotion in air and water. It is proposed that the Strouhal frequency constraint is but one consequence of the process of optimal vortex formation and that others remain to be discovered.

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“…the frequency at which a maximum amplitude is achieved with a minimum input force. While resonant frequencies are to be avoided in man-made constructions, achieving resonance is actually desirable in animal locomotion as it minimizes locomotor cost (Farley et al, 1993;Ahlborn et al, 2006).…”

Section: Introduction Tendons As Elastic Energy Storesmentioning

confidence: 99%

The role of hind limb tendons in gibbon locomotion: springs or strings?

Vereecke

Channon

2013

Journal of Experimental Biology

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SUMMARYTendon properties have an important effect on the mechanical behaviour of muscles, with compliant tendons allowing nearisometric muscle contraction and facilitating elastic energy storage and recoil. Stiff tendons, in contrast, facilitate rapid force transfer and precise positional control. In humans, the long Achilles tendon contributes to the mechanical efficiency of running via elastic energy storage and recovery, and its presence has been linked to the evolution of habitual bipedalism. Gibbons also possess relatively long hind limb tendons; however, their role is as yet unknown. Based on their large dimensions, and inferring from the situation in humans, we hypothesize that the tendons in the gibbon hind limb will facilitate elastic energy storage and recoil during hind-limb-powered locomotion. To investigate this, we determined the material properties of the gibbon Achilles and patellar tendon in vitro and linked this with available kinematic and kinetic data to evaluate their role in leaping and bipedalism. Tensile tests were conducted on tendon samples using a material testing machine and the load-displacement data were used to calculate stiffness, Young's modulus and hysteresis. In addition, the average stress-in-life and energy absorption capacity of both tendons were estimated. We found a functional difference between the gibbon Achilles and patellar tendon, with the Achilles tendon being more suitable for elastic energy storage and release. The patellar tendon, in contrast, has a relatively high hysteresis, making it less suitable to act as elastic spring. This suggests that the gibbon Achilles tendon might fulfil a similar function as in humans, contributing to reducing the locomotor cost of bipedalism by acting as elastic spring, while the high stiffness of the patellar tendon might favour fast force transfer upon recoil and, possibly, enhance leaping performance.

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Frequency tuning in animal locomotion

Cited by 42 publications

References 27 publications

Analytical insights into optimality and resonance in fish swimming

Analytical insights into optimality and resonance in fish swimming

Optimal Vortex Formation as a Unifying Principle in Biological Propulsion

The role of hind limb tendons in gibbon locomotion: springs or strings?

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