1
|
Wold ES, Aiello B, Harris M, Bin Sikandar U, Lynch J, Gravish N, Sponberg S. Moth resonant mechanics are tuned to wingbeat frequency and energetic demands. Proc Biol Sci 2024; 291:20240317. [PMID: 38920055 DOI: 10.1098/rspb.2024.0317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 05/15/2024] [Indexed: 06/27/2024] Open
Abstract
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 benefits for an insect that matches its wingbeat frequency to its resonant frequency, recent work has shown that moths may operate off their resonant peak. We hypothesized that across species, wingbeat frequency scales with resonance frequency to maintain favourable 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 model of resonant aerodynamics to determine how components of an insect's flight apparatus (stiffness, 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.
Collapse
Affiliation(s)
- Ethan S Wold
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - Brett Aiello
- School of Natural and Health Sciences, Seton Hill University , Greensburg, PA 15601, USA
| | - Manon Harris
- School of Physics, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - Usama Bin Sikandar
- School of Electrical and Computer Engineering, Georgia Institute of Technology , Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California San Diego , San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California San Diego , San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Biological Sciences, Georgia Institute of Technology , Atlanta, GA 30332, USA
- School of Physics, Georgia Institute of Technology , Atlanta, GA 30332, USA
| |
Collapse
|
2
|
Li Y, Li K, Fu F, Li Y, Li B. The Functions of Phasic Wing-Tip Folding on Flapping-Wing Aerodynamics. Biomimetics (Basel) 2024; 9:183. [PMID: 38534868 DOI: 10.3390/biomimetics9030183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 03/14/2024] [Accepted: 03/14/2024] [Indexed: 03/28/2024] Open
Abstract
Insects produce a variety of highly acrobatic maneuvers in flight owing to their ability to achieve various wing-stroke trajectories. Among them, beetles can quickly change their flight velocities and make agile turns. In this work, we report a newly discovered phasic wing-tip-folding phenomenon and its aerodynamic basis in beetles. The wings' flapping trajectories and aerodynamic forces of the tethered flying beetles were recorded simultaneously via motion capture cameras and a force sensor, respectively. The results verified that phasic active spanwise-folding and deployment (PASFD) can exist during flapping flight. The folding of the wing-tips of beetles significantly decreased aerodynamic forces without any changes in flapping frequency. Specifically, compared with no-folding-and-deployment wings, the lift and forward thrust generated by bilateral-folding-and-deployment wings reduced by 52.2% and 63.0%, respectively. Moreover, unilateral-folding-and-deployment flapping flight was found, which produced a lateral force (8.65 mN). Therefore, a micro-flapping-wing mechanism with PASFD was then designed, fabricated, and tested in a motion capture and force measurement system to validate its phasic folding functions and aerodynamic performance under different operating frequencies. The results successfully demonstrated a significant decrease in flight forces. This work provides valuable insights for the development of flapping-wing micro-air-vehicles with high maneuverability.
Collapse
Affiliation(s)
- Yiming Li
- Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robots, Harbin Institute of Technology, Shenzhen 518055, China
- Key University Laboratory of Mechanism & Machine Theory and Intelligent Unmanned Systems of Guangdong, Harbin Institute of Technology, Shenzhen 518055, China
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen 518055, China
| | - Keyu Li
- Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robots, Harbin Institute of Technology, Shenzhen 518055, China
- Key University Laboratory of Mechanism & Machine Theory and Intelligent Unmanned Systems of Guangdong, Harbin Institute of Technology, Shenzhen 518055, China
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen 518055, China
| | - Fang Fu
- College of Art and Design, Shenzhen University, Shenzhen 518060, China
| | - Yao Li
- Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robots, Harbin Institute of Technology, Shenzhen 518055, China
- Key University Laboratory of Mechanism & Machine Theory and Intelligent Unmanned Systems of Guangdong, Harbin Institute of Technology, Shenzhen 518055, China
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen 518055, China
| | - Bing Li
- Guangdong Provincial Key Laboratory of Intelligent Morphing Mechanisms and Adaptive Robots, Harbin Institute of Technology, Shenzhen 518055, China
- Key University Laboratory of Mechanism & Machine Theory and Intelligent Unmanned Systems of Guangdong, Harbin Institute of Technology, Shenzhen 518055, China
- School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen 518055, China
| |
Collapse
|
3
|
Gau J, Lynch J, Aiello B, Wold E, Gravish N, Sponberg S. Bridging two insect flight modes in evolution, physiology and robophysics. Nature 2023; 622:767-774. [PMID: 37794191 PMCID: PMC10599994 DOI: 10.1038/s41586-023-06606-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 09/04/2023] [Indexed: 10/06/2023]
Abstract
Since taking flight, insects have undergone repeated evolutionary transitions between two seemingly distinct flight modes1-3. Some insects neurally activate their muscles synchronously with each wingstroke. However, many insects have achieved wingbeat frequencies beyond the speed limit of typical neuromuscular systems by evolving flight muscles that are asynchronous with neural activation and activate in response to mechanical stretch2-8. These modes reflect the two fundamental ways of generating rhythmic movement: time-periodic forcing versus emergent oscillations from self-excitation8-10. How repeated evolutionary transitions have occurred and what governs the switching between these distinct modes remain unknown. Here we find that, despite widespread asynchronous actuation in insects across the phylogeny3,6, asynchrony probably evolved only once at the order level, with many reversions to the ancestral, synchronous mode. A synchronous moth species, evolved from an asynchronous ancestor, still preserves the stretch-activated muscle physiology. Numerical and robophysical analyses of a unified biophysical framework reveal that rather than a dichotomy, these two modes are two regimes of the same dynamics. Insects can transition between flight modes across a bridge in physiological parameter space. Finally, we integrate these two actuation modes into an insect-scale robot11-13 that enables transitions between modes and unlocks a new self-excited wingstroke strategy for engineered flight. Together, this framework accounts for repeated transitions in insect flight evolution and shows how flight modes can flip with changes in physiological parameters.
Collapse
Affiliation(s)
- Jeff Gau
- Interdisciplinary Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - James Lynch
- Mechanical and Aerospace Engineering Department, University of California San Diego, San Diego, CA, USA
| | - Brett Aiello
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Department of Biology, Seton Hill University, Greensburg, PA, USA
| | - Ethan Wold
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Quantitative Biosciences Graduate Program, Georgia Institute of Technology, Atlanta, GA, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering Department, University of California San Diego, San Diego, CA, USA.
| | - Simon Sponberg
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA.
| |
Collapse
|
4
|
Wold ES, Lynch J, Gravish N, Sponberg S. Structural damping renders the hawkmoth exoskeleton mechanically insensitive to non-sinusoidal deformations. J R Soc Interface 2023; 20:20230141. [PMID: 37194272 PMCID: PMC10189308 DOI: 10.1098/rsif.2023.0141] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/25/2023] [Indexed: 05/18/2023] Open
Abstract
Muscles act through elastic and dissipative elements to mediate movement, which can introduce dissipation and filtering which are important for energetics and control. The high power requirements of flapping flight can be reduced by an insect's exoskeleton, which acts as a spring with frequency-independent material properties under purely sinusoidal deformation. However, this purely sinusoidal dynamic regime does not encompass the asymmetric wing strokes of many insects or non-periodic deformations induced by external perturbations. As such, it remains unknown whether a frequency-independent model applies broadly and what implications it has for control. We used a vibration testing system to measure the mechanical properties of isolated Manduca sexta thoraces under symmetric, asymmetric and band-limited white noise deformations. The asymmetric and white noise conditions represent two types of generalized, multi-frequency deformations that may be encountered during steady-state and perturbed flight. Power savings and dissipation were indistinguishable between symmetric and asymmetric conditions, demonstrating that no additional energy is required to deform the thorax non-sinusoidally. Under white noise conditions, stiffness and damping were invariant with frequency, suggesting that the thorax has no frequency-dependent filtering properties. A simple flat frequency response function fits our measured frequency response. This work demonstrates the potential of materials with frequency-independent damping to simplify motor control by eliminating any velocity-dependent filtering that viscoelastic elements usually impose between muscle and wing.
Collapse
Affiliation(s)
- Ethan S. Wold
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
5
|
Amichai E, Boerma DB, Page RA, Swartz SM, ter Hofstede HM. By a whisker: the sensory role of vibrissae in hovering flight in nectarivorous bats. Proc Biol Sci 2023; 290:20222085. [PMID: 36722088 PMCID: PMC9890094 DOI: 10.1098/rspb.2022.2085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/23/2022] [Indexed: 02/02/2023] Open
Abstract
Whiskers are important tactile structures widely used across mammals for a variety of sensory functions, but it is not known how bats-representing about a fifth of all extant mammal species-use them. Nectar-eating bats typically have long vibrissae (long, stiff hairs) arranged in a forward-facing brush-like formation that is not present in most non-nectarivorous bats. They also commonly use a unique flight strategy to access their food-hovering flight. Here we investigated whether these species use their vibrissae to optimize their feeding by assisting fine flight control. We used behavioural experiments to test if bats' flight trajectory into the flower changed after vibrissa removal, and phylogenetic comparative methods to test whether vibrissa length is related to nectarivory. We found that bat flight trajectory was altered after vibrissae removal and that nectarivorous bats possess longer vibrissae than non-nectivorous species, providing evidence of an additional source of information in bats' diverse sensory toolkit.
Collapse
Affiliation(s)
- Eran Amichai
- Ecology, Evolution, Environment & Society Graduate Program, Dartmouth College, Hanover, NH 03755, USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - David B. Boerma
- Department of Mammalogy, Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Rachel A. Page
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado 0843-03092, Republic of Panama
| | - Sharon M. Swartz
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI 012912, USA
- School of Engineering, Brown University, Providence, RI 012912, USA
| | - Hannah M. ter Hofstede
- Ecology, Evolution, Environment & Society Graduate Program, Dartmouth College, Hanover, NH 03755, USA
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado 0843-03092, Republic of Panama
| |
Collapse
|
6
|
Sutton GP, St Pierre R, Kuo CY, Summers AP, Bergbreiter S, Cox S, Patek SN. Dual spring force couples yield multifunctionality and ultrafast, precision rotation in tiny biomechanical systems. J Exp Biol 2022; 225:275995. [PMID: 35863219 DOI: 10.1242/jeb.244077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 06/15/2022] [Indexed: 12/31/2022]
Abstract
Small organisms use propulsive springs rather than muscles to repeatedly actuate high acceleration movements, even when constrained to tiny displacements and limited by inertial forces. Through integration of a large kinematic dataset, measurements of elastic recoil, energetic math modeling and dynamic math modeling, we tested how trap-jaw ants (Odontomachus brunneus) utilize multiple elastic structures to develop ultrafast and precise mandible rotations at small scales. We found that O. brunneus develops torque on each mandible using an intriguing configuration of two springs: their elastic head capsule recoils to push and the recoiling muscle-apodeme unit tugs on each mandible. Mandibles achieved precise, planar, circular trajectories up to 49,100 rad s-1 (470,000 rpm) when powered by spring propulsion. Once spring propulsion ended, the mandibles moved with unconstrained and oscillatory rotation. We term this mechanism a 'dual spring force couple', meaning that two springs deliver energy at two locations to develop torque. Dynamic modeling revealed that dual spring force couples reduce the need for joint constraints and thereby reduce dissipative joint losses, which is essential to the repeated use of ultrafast, small systems. Dual spring force couples enable multifunctionality: trap-jaw ants use the same mechanical system to produce ultrafast, planar strikes driven by propulsive springs and for generating slow, multi-degrees of freedom mandible manipulations using muscles, rather than springs, to directly actuate the movement. Dual spring force couples are found in other systems and are likely widespread in biology. These principles can be incorporated into microrobotics to improve multifunctionality, precision and longevity of ultrafast systems.
Collapse
Affiliation(s)
- Gregory P Sutton
- School of Life Sciences , University of Lincoln, Lincoln LN6 7TS, UK
| | - Ryan St Pierre
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA
| | - Chi-Yun Kuo
- Biology Department, Duke University, Durham, NC 27708, USA
| | - Adam P Summers
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - Sarah Bergbreiter
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Suzanne Cox
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA
| | - S N Patek
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA
| |
Collapse
|
7
|
Gau J, Wold ES, Lynch J, Gravish N, Sponberg S. The hawkmoth wingbeat is not at resonance. Biol Lett 2022; 18:20220063. [PMID: 35611583 DOI: 10.1098/rsbl.2022.0063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Flying insects have elastic materials within their exoskeletons that could reduce the energetic cost of flight if their wingbeat frequency is matched to a mechanical resonance frequency. Flapping at resonance may be essential across flying insects because of the power demands of small-scale flapping flight. However, building up large-amplitude resonant wingbeats over many wingstrokes may be detrimental for control if the total mechanical energy in the spring-wing system exceeds the per-cycle work capacity of the flight musculature. While the mechanics of the insect flight apparatus can behave as a resonant system, the question of whether insects flap their wings at their resonant frequency remains unanswered. Using previous measurements of body stiffness in the hawkmoth, Manduca sexta, we develop a mechanical model of spring-wing resonance with aerodynamic damping and characterize the hawkmoth's resonant frequency. We find that the hawkmoth's wingbeat frequency is approximately 80% above resonance and remains so when accounting for uncertainty in model parameters. In this regime, hawkmoths may still benefit from elastic energy exchange while enabling control of aerodynamic forces via frequency modulation. We conclude that, while insects use resonant mechanics, tuning wingbeats to a simple resonance peak is not a necessary feature for all centimetre-scale flapping flyers.
Collapse
Affiliation(s)
- Jeff Gau
- Interdisciplinary Bioengineering Graduate Program and George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Ethan S Wold
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California, San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California, San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
8
|
Pons A, Beatus T. Distinct forms of resonant optimality within insect indirect flight motors. J R Soc Interface 2022; 19:20220080. [PMID: 35582811 DOI: 10.1098/rsif.2022.0080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Insect flight motors are extraordinary natural structures that operate efficiently at high frequencies. Structural resonance is thought to play a role in ensuring efficient motor operation, but the details of this role are elusive. While the efficiency benefits associated with resonance may be significant, a range of counterintuitive behaviours are observed. In particular, the relationship between insect wingbeat frequencies and thoracic natural frequencies is uncertain, with insects showing wingbeat frequency modulation over both short and long time scales. Here, we offer new explanations for this modulation. We show how, in linear and nonlinear models of an indirect flight motor, resonance is not a unitary state at a single frequency, but a complex cluster of distinct and mutually exclusive states, each representing a different form of resonant optimality. Additionally, by characterizing the relationship between resonance and the state of negative work absorption within the motor, we demonstrate how near-perfect resonant energetic optimality can be maintained over significant wingbeat frequency ranges. Our analysis leads to a new conceptual model of flight motor operation: one in which insects are not energetically restricted to a precise wingbeat frequency, but instead are robust to changes in thoracic and environmental properties-an illustration of the extraordinary robustness of these natural motors.
Collapse
Affiliation(s)
- Arion Pons
- The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel.,The Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Israel
| | - Tsevi Beatus
- The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Israel.,The Benin School of Computer Science and Engineering, The Hebrew University of Jerusalem, Israel
| |
Collapse
|
9
|
Vallejo-Marín M. How and why do bees buzz? Implications for buzz pollination. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:1080-1092. [PMID: 34537837 PMCID: PMC8866655 DOI: 10.1093/jxb/erab428] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Buzz pollination encompasses the evolutionary convergence of specialized floral morphologies and pollinator behaviour in which bees use vibrations (floral buzzes) to remove pollen. Floral buzzes are one of several types of vibrations produced by bees using their thoracic muscles. Here I review how bees can produce these different types of vibrations and discuss the implications of this mechanistic understanding for buzz pollination. I propose that bee buzzes can be categorized according to their mode of production and deployment into: (i) thermogenic, which generate heat with little mechanical vibration; (ii) flight buzzes which, combined with wing deployment and thoracic vibration, power flight; and (iii) non-flight buzzes in which the thorax vibrates but the wings remain mostly folded, and include floral, defence, mating, communication, and nest-building buzzes. I hypothesize that the characteristics of non-flight buzzes, including floral buzzes, can be modulated by bees via modification of the biomechanical properties of the thorax through activity of auxiliary muscles, changing the rate of activation of the indirect flight muscles, and modifying flower handling behaviours. Thus, bees should be able to fine-tune mechanical properties of their floral vibrations, including frequency and amplitude, depending on flower characteristics and pollen availability to optimize energy use and pollen collection.
Collapse
Affiliation(s)
- Mario Vallejo-Marín
- Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK
| |
Collapse
|
10
|
Biewener AA, Bomphrey RJ, Daley MA, Ijspeert AJ. Stability and manoeuvrability in animal movement: lessons from biology, modelling and robotics. Proc Biol Sci 2022; 289:20212492. [PMID: 35042414 PMCID: PMC8767207 DOI: 10.1098/rspb.2021.2492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Andrew A Biewener
- Concord Field Station, Department of Organismic and Evolutionary Biology, Harvard University
| | - Richard J Bomphrey
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
| | - Monica A Daley
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA
| | - Auke J Ijspeert
- Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| |
Collapse
|
11
|
Gau J, Gemilere R, Fm Subteam LV, Lynch J, Gravish N, Sponberg S. Rapid frequency modulation in a resonant system: aerial perturbation recovery in hawkmoths. Proc Biol Sci 2021; 288:20210352. [PMID: 34034520 DOI: 10.1098/rspb.2021.0352] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Centimetre-scale fliers must contend with the high power requirements of flapping flight. Insects have elastic elements in their thoraxes which may reduce the inertial costs of their flapping wings. Matching wingbeat frequency to a mechanical resonance can be energetically favourable, but also poses control challenges. Many insects use frequency modulation on long timescales, but wingstroke-to-wingstroke modulation of wingbeat frequencies in a resonant spring-wing system is potentially costly because muscles must work against the elastic flight system. Nonetheless, rapid frequency and amplitude modulation may be a useful control modality. The hawkmoth Manduca sexta has an elastic thorax capable of storing and returning significant energy. However, its nervous system also has the potential to modulate the driving frequency of flapping because its flight muscles are synchronous. We tested whether hovering hawkmoths rapidly alter frequency during perturbations with vortex rings. We observed both frequency modulation (32% around mean) and amplitude modulation (37%) occurring over several wingstrokes. Instantaneous phase analysis of wing kinematics revealed that more than 85% of perturbation responses required active changes in neurogenic driving frequency. Unlike their robotic counterparts that abdicate frequency modulation for energy efficiency, synchronous insects use wingstroke-to-wingstroke frequency modulation despite the power demands required for deviating from resonance.
Collapse
Affiliation(s)
- Jeff Gau
- Interdisciplinary Bioengineering Graduate Program and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Ryan Gemilere
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Lds-Vip Fm Subteam
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James Lynch
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Nick Gravish
- Mechanical and Aerospace Engineering, University of California San Diego, San Diego, CA 92161, USA
| | - Simon Sponberg
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|