Flexibility and control of thorax deformation during hawkmoth flight

Ando, Noriyasu; Kanzaki, Ryohei

doi:10.1098/rsbl.2015.0733

Cited by 32 publications

(57 citation statements)

References 8 publications

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“…Although the exoskeleton is a single, continuous structure, functional specialization of thorax regions decouples P return and P lost . For instance, the wing joint must withstand the high strains necessary for wing movement whereas the scutum may be optimized for spring-like behavior [19]. Because dissipation occurs primarily in the wing joint, the addition of scutum deformations via indirect actuation increases P return by 50% but does does not increase P lost .…”

Section: Strain Coupling Improves Energy Exchange Performancementioning

confidence: 99%

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Indirect actuation reduces flight power requirements inManduca sextavia elastic energy exchange

Gau

Gravish

Sponberg

2019

Preprint

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In the vast majority of flying insects, wing movements are generated indirectly via the deformations of the exoskeleton. Indirect measurements of inertial and aerodynamic power requirements suggest that elastic energy exchange in spring-like structures may reduce the high power requirements of flight by recovering energy from one wingstroke to the next. We directly measured deformation mechanics and elastic energy storage in a hawkmoth Manduca sexta thorax by recording the force required to deform the thorax over a frequency range encompassing typical wingbeat frequencies. We found that a structural damping model, not a viscoelastic model, accurately describes the thorax's linear spring-like properties and frequency independent dissipation. The energy recovered from thorax deformations is sufficient to minimize flight power requirements. By removing the passive musculature, we find that the exoskeleton determines thorax mechanics. To assess the factors that determine the exoskeleton's spring-like properties, we isolated functional thorax regions, disrupted strain in an otherwise intact thorax, and compared results to a homogeneous hemisphere. We found that mechanical coupling between spatially separated thorax regions improves energy exchange performance. Furthermore, local mechanical properties depend on global strain patterns. Finally, the addition of scutum deformations via indirect actuation provides additional energy recovery without added dissipation.

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Section: Strain Coupling Improves Energy Exchange Performancementioning

confidence: 99%

“…In addition, large amplitude heterogeneous strain may concentrate deformations in regions with unfavorable properties for energy exchange (Fig. 2 d) [19]. Thus, interactions between exoskeletal shape and material composition are significant for determining elastic energy exchange capacity.…”

Section: Introductionmentioning

confidence: 99%

Indirect actuation reduces flight power requirements inManduca sextavia elastic energy exchange

Gau

Gravish

Sponberg

2019

Preprint

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“…For a hawkmoth, it was found that flexibility and control of thorax deformation were dependent upon the interaction between neuromuscular systems and body mechanics, and that locally amplified dorsal thorax deformation near the wing-hinge could ensure sufficient wing movement and the phase asymmetry in terms of dorsal thorax oscillations and wing beats [58]. …”

Section: Biomechanics In Insect Flight: Aerodynamics Flight Dynamicsmentioning

confidence: 99%

“…Wing-hinges in insects are flexible structures, which, based on an experimental study of fruit fly saccade [ 31 ], was identified to act like a damped torsional spring and work well to passively resist the wing-tendency to flip in response to aerodynamic and inertial forces, making the pitch control rather simple. For a hawkmoth, it was found that flexibility and control of thorax deformation were dependent upon the interaction between neuromuscular systems and body mechanics, and that locally amplified dorsal thorax deformation near the wing-hinge could ensure sufficient wing movement and the phase asymmetry in terms of dorsal thorax oscillations and wing beats [ 58 ].…”

Section: Biomechanics In Insect Flight: Aerodynamics Flight Dynamicsmentioning

confidence: 99%

Biomechanics and biomimetics in insect-inspired flight systems

Ravi

Kolomenskiy

et al. 2016

Phil. Trans. R. Soc. B

104

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Insect- and bird-size drones—micro air vehicles (MAV) that can perform autonomous flight in natural and man-made environments are now an active and well-integrated research area. MAVs normally operate at a low speed in a Reynolds number regime of 104–105 or lower, in which most flying animals of insects, birds and bats fly, and encounter unconventional challenges in generating sufficient aerodynamic forces to stay airborne and in controlling flight autonomy to achieve complex manoeuvres. Flying insects that power and control flight by flapping wings are capable of sophisticated aerodynamic force production and precise, agile manoeuvring, through an integrated system consisting of wings to generate aerodynamic force, muscles to move the wings and a control system to modulate power output from the muscles. In this article, we give a selective review on the state of the art of biomechanics in bioinspired flight systems in terms of flapping and flexible wing aerodynamics, flight dynamics and stability, passive and active mechanisms in stabilization and control, as well as flapping flight in unsteady environments. We further highlight recent advances in biomimetics of flapping-wing MAVs with a specific focus on insect-inspired wing design and fabrication, as well as sensing systems.This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.

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“…One potential issue with using these estimates to inform our study, however, is that thorax velocity (from which displacement was estimated via integration) was measured at a single point on the thorax's dorsal surface with laser vibrometry. Ando and Kanzaki measured the dorsal surface of a hawkmoth Agrius convolvuli thorax using a high-speed profilometer found displacements varied significantly along the medial-lateral direction [27]. Thus, it is likely that thorax displacements estimated via single point laser vibrometry are sensitive to the precise location of the measurement.…”

Section: Dynamic Experimental Setupmentioning

confidence: 99%

Flapping at Resonance: Measuring the Frequency Response of the Hymenoptera Thorax

Jankauski

2019

Preprint

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Insects with asynchronous flight muscles are believed to flap at the fundamental frequency of their thorax or thorax-wing system. Flapping in this manner leverages the natural elasticity of the thorax to reduce the energetic requirements of flight. However, to the best of our knowledge, the fundamental frequency of the insect thorax has not been measured via vibration testing. Here, we measure the linear frequency response function (FRF) of several Hymonptera (Apis mellifera, Polistes dominula, Bombus huntii ) thoraxes about their equilibrium states in order to determine their fundamental frequencies. FRFs relate the input force to output acceleration at the insect tergum and are acquired via a mechanical vibration shaker assembly. When compressed 50 µm, thorax fundamental frequencies in all specimens approximately 50-150% higher than reported wingbeat frequencies. We suspect that the measured fundamental frequencies are higher in the experiment than during flight due to experimental boundary conditions that stiffen the thorax. Thus, our results corroborate the idea that some insects flap at the fundamental frequency of their thorax. Next, we compress the thorax between 100 -300 µm in 50 µm intervals to assess the sensitivity of the fundamental frequency to geometric modifications. For all insects considered, the thorax fundamental frequency increased nearly monotonically with respect to level of compression. This implies that the thorax behaves a nonlinear hardening spring, which we confirmed via static force-displacement testing. Hardening behavior may provide a simple mechanism for the insect to adjust wingbeat frequency, and implies the thorax may behave as a nonlinear Duffing oscillator excited at large amplitude. The Duffing oscillator exhibits amplitude-dependent resonance and may serve as a useful model to increase the flapping frequency bandwidth of small resonanttype flapping wing micro air vehicles.

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Flexibility and control of thorax deformation during hawkmoth flight

Cited by 32 publications

References 8 publications

Indirect actuation reduces flight power requirements inManduca sextavia elastic energy exchange

Indirect actuation reduces flight power requirements inManduca sextavia elastic energy exchange

Biomechanics and biomimetics in insect-inspired flight systems

Flapping at Resonance: Measuring the Frequency Response of the Hymenoptera Thorax

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