Autonomous Actuation of Flapping Wing Robots Inspired by Asynchronous Insect Muscle

Lynch, James; Gau, Jeff; Sponberg, Simon; Gravish, Nick

doi:10.1109/icra46639.2022.9812028

Cited by 8 publications

(10 citation statements)

References 37 publications

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“…A more realistic model is the nonlinear formulation of quadratic damping, i.e. aerodynamic drag [5,26],…”

Section: Modelling Flight Motor Oscillation 21 Modelling Flight Motor...mentioning

confidence: 99%

“…A more realistic model is the nonlinear formulation of quadratic damping, i.e. aerodynamic drag [5,26], 4pt1emMx¨+Cx˙falsefalse|x˙falsefalse|+Kx=F,x¨+βx˙falsefalse|x˙falsefalse|+ω02x=f,β=true0CM,ω02=KM,1emf=true0FM,with quadratic damping parameter β . To improve model fidelity further, exoskeletal structural damping [27,28] can be added.…”

Section: Modelling Flight Motor Oscillationmentioning

confidence: 99%

“…It is possible to fit equation (3.5) directly to this impulse-response data; cf . [5], but raw data and the full set of fitted rate constants ( b , c , …) are rarely reported [42]; and amplitude constants ( B , C , …) are typically unreported. For this reason, we develop our own time-independent impulse-response (TIIR) estimates of the peak r , based on only a few reported SA/SD measurements—accounting for the directionally nonlinear distinction between SA and SD.…”

Section: Modelling Asynchronous Muscle Stretch-activationmentioning

confidence: 99%

“…The dipteran flight motor, under stretch activation, is a system that converts a form of energy that has no inherent periodicity-chemical energy, in adenosine triphosphate (ATP)-into periodic oscillation. As such, it is a dynamically unstable, self-oscillating system [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…However, a remarkable feature of the results of Machin and Pringle [4] is now seldom noted: in a general system, there is no particular reason why self-oscillation and resonance should align [13]. Indeed, both older [14] and recent [5] analyses of insect self-oscillation models indicate that convergence to a resonant frequency is not a guaranteed property of the motor system. The identification of multiple resonant frequencies within even simple models of the dipteran flight motor—frequencies split by damping and by the distribution of stiffness/elasticity [6]—adds further colour to this picture.…”

Section: Introductionmentioning

confidence: 99%

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The self-oscillation paradox in the flight motor ofDrosophila melanogaster

Pons

2023

J. R. Soc. Interface.

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Tiny flying insects, such as Drosophila melanogaster , fly by flapping their wings at frequencies faster than their brains are able to process. To do so, they rely on self-oscillation: dynamic instability, leading to emergent oscillation, arising from muscle stretch-activation. Many questions concerning this vital natural instability remain open. Does flight motor self-oscillation necessarily lead to resonance—a state optimal in efficiency and/or performance? If so, what state? And is self-oscillation even guaranteed in a motor driven by stretch-activated muscle, or are there limiting conditions? In this work, we use data-driven models of wingbeat and muscle behaviour to answer these questions. Developing and leveraging novel analysis techniques, including symbolic computation, we establish a fundamental condition for motor self-oscillation common to a wide range of motor models. Remarkably, D. melanogaster flight apparently defies this condition: a paradox of motor operation. We explore potential resolutions to this paradox, and, within its confines, establish that the D. melanogaster flight motor is probably not resonant with respect to exoskeletal elasticity: instead, the muscular elasticity plays a dominant role. Contrary to common supposition, the stiffness of stretch-activated muscle is an obstacle to, rather than an enabler of, the operation of the D. melanogaster flight motor.

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“…A more realistic model is the nonlinear formulation of quadratic damping, i.e. aerodynamic drag [5,26],…”

Section: Modelling Flight Motor Oscillation 21 Modelling Flight Motor...mentioning

confidence: 99%

Section: Modelling Flight Motor Oscillationmentioning

confidence: 99%

Section: Modelling Asynchronous Muscle Stretch-activationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The self-oscillation paradox in the flight motor ofDrosophila melanogaster

Pons

2023

J. R. Soc. Interface.

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Solving the thoracic inverse problem in the fruit fly

et al. 2023

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In many insect species, the thoracic exoskeletal structure plays a crucial role in enabling flight. In the dipteran indirect flight mechanism, thoracic cuticle acts as a transmission link between the flight muscles and the wings, and is thought to act as an elastic modulator: improving flight motor efficiency thorough linear or nonlinear resonance. But peering closely into the drivetrain of tiny insects is experimentally difficult, and the nature of this elastic modulation is unclear. Here, we present a new inverse-problem methodology to surmount this difficulty. In a data synthesis process, we integrate literature-reported rigid-wing aerodynamic and musculoskeletal data into a planar oscillator model for the fruit fly Drosophila melanogaster, and use this integrated data to identify several surprising properties of the fly's thorax. We find that fruit flies likely have an energetic need for motor resonance: absolute power savings due to motor elasticity range from 0-30% across literature-reported datasets, averaging 16%. However, in all cases, the intrinsic high effective stiffness of the active asynchronous flight muscles accounts for all elastic energy storage required by the wingbeat. The D. melanogaster flight motor should be considered as a system in which the wings are resonant with the elastic effects of the motor’s asynchronous musculature, and not with the elastic effects of the thoracic exoskeleton. We discover also that D. melanogaster wingbeat kinematics show subtle adaptions that ensure that wingbeat load requirements match muscular forcing. Together, these newly-identified properties suggest a novel conceptual model of the fruit fly's flight motor: a structure that is resonant due to muscular elasticity, and is thereby intensely concerned with ensuring that the primary flight muscles are operating efficiently. Our inverse-problem methodology sheds new light on the complex behaviour of these tiny flight motors, and provides avenues for further studies in a range of other insect species.

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Moth resonant mechanics are tuned to wingbeat frequency and energetic demands

Wold,

Aiello,

Harris

et al. 2024

Preprint

Self Cite

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An insect’s wingbeat frequency is a critical determinant of its flight performance and varies by multiple orders of magnitude across Insecta. Despite potential energetic and kine-matic benefits for an insect that matches its wingbeat frequency to its resonant frequency, recent work has shown that moths may operate off of their resonant peak. We hypothesized that across species, wingbeat frequency scales with resonance frequency to maintain favorable energetics, but with an offset in species that use frequency modulation as a means of flight control. The moth superfamily Bombycoidea is ideal for testing this hypothesis because their wingbeat frequencies vary across species by an order of magnitude, despite similar morphology and actuation. We used materials testing, high-speed videography, and a “spring-wing” model of resonant aerodynamics to determine how components of an insect’s flight apparatus (thoracic properties, wing inertia, muscle strain, and aerodynamics) vary with wingbeat frequency. We find that the resonant frequency of a moth correlates with wingbeat frequency, but resonance curve shape (described by the Weis-Fogh number) and peak location vary within the clade in a way that corresponds to frequency-dependent biomechanical demands. Our results demonstrate that a suite of adaptations in muscle, exoskeleton and wing drive variation in resonant mechanics, reflecting potential constraints on matching wingbeat and resonant frequencies.

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Autonomous Actuation of Flapping Wing Robots Inspired by Asynchronous Insect Muscle

Cited by 8 publications

References 37 publications

The self-oscillation paradox in the flight motor ofDrosophila melanogaster

The self-oscillation paradox in the flight motor ofDrosophila melanogaster

Solving the thoracic inverse problem in the fruit fly

Moth resonant mechanics are tuned to wingbeat frequency and energetic demands

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