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Active and passive stabilization of body pitch in insect flight.

Ristroph L, Ristroph G, Morozova S, Bergou AJ, Chang S, Guckenheimer J, Wang ZJ, Cohen I - J R Soc Interface (2013)

Bottom Line: Flying insects have evolved sophisticated sensory-motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities.By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability.Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Cornell University, Ithaca, NY 14853, USA. ristroph@cims.nyu.edu

ABSTRACT
Flying insects have evolved sophisticated sensory-motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities. We describe a theory that predicts the instability growth rate in body pitch from flapping-wing aerodynamics and reveals two ways of achieving balanced flight: active control with sufficiently rapid reactions and passive stabilization with high body drag. By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability. Moreover, we find that fruit flies with their control sensors disabled can keep upright if high-drag fibres are also attached to their bodies, an observation consistent with our prediction for the passive stability condition. Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.

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Fruit flies quickly overcome in-flight perturbations. (a) Reconstruction of a flight perturbation filmed with three high-speed cameras. Selected images are shown on the side panels, and the measured configurations of the insect (body length 2.7 mm) are displayed on the model. A black bar on the insect body highlights its pitch orientation. As the insect ascends from left to right, an impulsive magnetic field (blue arrow) induces a nose-down torque on the ferromagnetic pin glued to its back. (b) Perturbations are applied to the body pitch orientation, and the insect responds with changes to the wing-stroke angle. (c) By sweeping its wings further in front, the insect generates a nose-up corrective torque. (d) Body pitch (solid blue line) and wing-stroke (dashed red line) angles, with each quantity shifted so that the average pre-perturbation value is zero. The magnetic torque perturbation (thin blue stripe) tips the insect downwards, and the insect responds by correcting its orientation. After a reaction time of 12 ms (thick red stripe), the fly generates corrective wing motions. Each gray and white stripe denotes a wing beat, with a typical period of about 4 ms. (e) Histogram of reaction times measured in 12 perturbation experiments. (Online version in colour.)
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RSIF20130237F1: Fruit flies quickly overcome in-flight perturbations. (a) Reconstruction of a flight perturbation filmed with three high-speed cameras. Selected images are shown on the side panels, and the measured configurations of the insect (body length 2.7 mm) are displayed on the model. A black bar on the insect body highlights its pitch orientation. As the insect ascends from left to right, an impulsive magnetic field (blue arrow) induces a nose-down torque on the ferromagnetic pin glued to its back. (b) Perturbations are applied to the body pitch orientation, and the insect responds with changes to the wing-stroke angle. (c) By sweeping its wings further in front, the insect generates a nose-up corrective torque. (d) Body pitch (solid blue line) and wing-stroke (dashed red line) angles, with each quantity shifted so that the average pre-perturbation value is zero. The magnetic torque perturbation (thin blue stripe) tips the insect downwards, and the insect responds by correcting its orientation. After a reaction time of 12 ms (thick red stripe), the fly generates corrective wing motions. Each gray and white stripe denotes a wing beat, with a typical period of about 4 ms. (e) Histogram of reaction times measured in 12 perturbation experiments. (Online version in colour.)

Mentions: A typical flight perturbation experiment is shown in the reconstruction of figure 1a. Selected images captured from each high-speed camera are shown on the side panels, and the extracted body and wing configurations are displayed on the model insect. A black cylinder is drawn through its long axis, highlighting the changes to body pitch orientation. As the insect ascends and progresses left to right, the magnetic torque is applied (curved arrow) and causes a nose-down rotation. The insect then recovers its pitch orientation by a nose-up rotation as it continues on its trajectory. We quantify these dynamics by measuring the pitch angle over time, and in figure 1d we display the deviations in the pitch relative to its mean value prior to the perturbation. The magnetic torque is applied for one wing beat (blue stripe) starting at time zero, and the body pitch then rapidly decreases by almost 20°. Pitch then increases to near its original value, making a recovery in about 60 ms or 15 wing beats.Figure 1.


Active and passive stabilization of body pitch in insect flight.

Ristroph L, Ristroph G, Morozova S, Bergou AJ, Chang S, Guckenheimer J, Wang ZJ, Cohen I - J R Soc Interface (2013)

Fruit flies quickly overcome in-flight perturbations. (a) Reconstruction of a flight perturbation filmed with three high-speed cameras. Selected images are shown on the side panels, and the measured configurations of the insect (body length 2.7 mm) are displayed on the model. A black bar on the insect body highlights its pitch orientation. As the insect ascends from left to right, an impulsive magnetic field (blue arrow) induces a nose-down torque on the ferromagnetic pin glued to its back. (b) Perturbations are applied to the body pitch orientation, and the insect responds with changes to the wing-stroke angle. (c) By sweeping its wings further in front, the insect generates a nose-up corrective torque. (d) Body pitch (solid blue line) and wing-stroke (dashed red line) angles, with each quantity shifted so that the average pre-perturbation value is zero. The magnetic torque perturbation (thin blue stripe) tips the insect downwards, and the insect responds by correcting its orientation. After a reaction time of 12 ms (thick red stripe), the fly generates corrective wing motions. Each gray and white stripe denotes a wing beat, with a typical period of about 4 ms. (e) Histogram of reaction times measured in 12 perturbation experiments. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043156&req=5

RSIF20130237F1: Fruit flies quickly overcome in-flight perturbations. (a) Reconstruction of a flight perturbation filmed with three high-speed cameras. Selected images are shown on the side panels, and the measured configurations of the insect (body length 2.7 mm) are displayed on the model. A black bar on the insect body highlights its pitch orientation. As the insect ascends from left to right, an impulsive magnetic field (blue arrow) induces a nose-down torque on the ferromagnetic pin glued to its back. (b) Perturbations are applied to the body pitch orientation, and the insect responds with changes to the wing-stroke angle. (c) By sweeping its wings further in front, the insect generates a nose-up corrective torque. (d) Body pitch (solid blue line) and wing-stroke (dashed red line) angles, with each quantity shifted so that the average pre-perturbation value is zero. The magnetic torque perturbation (thin blue stripe) tips the insect downwards, and the insect responds by correcting its orientation. After a reaction time of 12 ms (thick red stripe), the fly generates corrective wing motions. Each gray and white stripe denotes a wing beat, with a typical period of about 4 ms. (e) Histogram of reaction times measured in 12 perturbation experiments. (Online version in colour.)
Mentions: A typical flight perturbation experiment is shown in the reconstruction of figure 1a. Selected images captured from each high-speed camera are shown on the side panels, and the extracted body and wing configurations are displayed on the model insect. A black cylinder is drawn through its long axis, highlighting the changes to body pitch orientation. As the insect ascends and progresses left to right, the magnetic torque is applied (curved arrow) and causes a nose-down rotation. The insect then recovers its pitch orientation by a nose-up rotation as it continues on its trajectory. We quantify these dynamics by measuring the pitch angle over time, and in figure 1d we display the deviations in the pitch relative to its mean value prior to the perturbation. The magnetic torque is applied for one wing beat (blue stripe) starting at time zero, and the body pitch then rapidly decreases by almost 20°. Pitch then increases to near its original value, making a recovery in about 60 ms or 15 wing beats.Figure 1.

Bottom Line: Flying insects have evolved sophisticated sensory-motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities.By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability.Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Cornell University, Ithaca, NY 14853, USA. ristroph@cims.nyu.edu

ABSTRACT
Flying insects have evolved sophisticated sensory-motor systems, and here we argue that such systems are used to keep upright against intrinsic flight instabilities. We describe a theory that predicts the instability growth rate in body pitch from flapping-wing aerodynamics and reveals two ways of achieving balanced flight: active control with sufficiently rapid reactions and passive stabilization with high body drag. By glueing magnets to fruit flies and perturbing their flight using magnetic impulses, we show that these insects employ active control that is indeed fast relative to the instability. Moreover, we find that fruit flies with their control sensors disabled can keep upright if high-drag fibres are also attached to their bodies, an observation consistent with our prediction for the passive stability condition. Finally, we extend this framework to unify the control strategies used by hovering animals and also furnish criteria for achieving pitch stability in flapping-wing robots.

Show MeSH
Related in: MedlinePlus