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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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Active and passive stabilization of fruit fly flight. (a) Fruit flies use fast gyroscopic sensors called halteres to mediate flight control. Each haltere vibrates during flight and detects changes in body orientation. If glued down, the haltere no longer properly functions. (b) Dandelion seed fibres add drag to the insect body, thus increasing passive stability. (c) Inset: body orientation and flight trajectory of a fly with halteres disabled (left), showing a tumbling motion while falling downwards. When fibres are attached to a haltere-disabled insect, it is able to keep upright as it descends (right). Main figure: insects are released in air, and flight performance is assessed by measuring the trajectory angle with respect to the downward vertical. Distributions of flight angles for insects with halteres disabled (light grey) and insects with halteres disabled and with fibres attached (dark grey). (Online version in colour.)
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RSIF20130237F2: Active and passive stabilization of fruit fly flight. (a) Fruit flies use fast gyroscopic sensors called halteres to mediate flight control. Each haltere vibrates during flight and detects changes in body orientation. If glued down, the haltere no longer properly functions. (b) Dandelion seed fibres add drag to the insect body, thus increasing passive stability. (c) Inset: body orientation and flight trajectory of a fly with halteres disabled (left), showing a tumbling motion while falling downwards. When fibres are attached to a haltere-disabled insect, it is able to keep upright as it descends (right). Main figure: insects are released in air, and flight performance is assessed by measuring the trajectory angle with respect to the downward vertical. Distributions of flight angles for insects with halteres disabled (light grey) and insects with halteres disabled and with fibres attached (dark grey). (Online version in colour.)

Mentions: To offer further evidence that fruit flies rely on active control, we revisit classic experiments that disable the fast mechanical sensors of these insects [1,15,16]. As shown in figure 2a, the halteres of the fly are located below each wing and oscillate in flight, serving as gyroscopic sensors of body rotations. Here, we disable this sensory function by glueing the halteres to the abdomen and thereby preventing any oscillations. When released in still air, these sensor-disabled insects fall nearly straight down as indicated by the measured left trajectory in figure 2c. High-speed video shows that these flies are indeed flapping their wings at typical frequencies and amplitudes but that their body rapidly tumbles nonetheless, suggesting that a lack of orientational control undermines their flight. To quantify their flight performance, we release sensor-disabled flies from 1 m high and measure the radial distance these insects are able to travel. We then compute the flight angle as the inverse tangent of the ratio of the distance travelled to the initial drop height. A histogram of many trials is shown in light grey in figure 2c, and the typical flight trajectory angle near zero quantifies their poor flight performance.FigureĀ 2.


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)

Active and passive stabilization of fruit fly flight. (a) Fruit flies use fast gyroscopic sensors called halteres to mediate flight control. Each haltere vibrates during flight and detects changes in body orientation. If glued down, the haltere no longer properly functions. (b) Dandelion seed fibres add drag to the insect body, thus increasing passive stability. (c) Inset: body orientation and flight trajectory of a fly with halteres disabled (left), showing a tumbling motion while falling downwards. When fibres are attached to a haltere-disabled insect, it is able to keep upright as it descends (right). Main figure: insects are released in air, and flight performance is assessed by measuring the trajectory angle with respect to the downward vertical. Distributions of flight angles for insects with halteres disabled (light grey) and insects with halteres disabled and with fibres attached (dark grey). (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

RSIF20130237F2: Active and passive stabilization of fruit fly flight. (a) Fruit flies use fast gyroscopic sensors called halteres to mediate flight control. Each haltere vibrates during flight and detects changes in body orientation. If glued down, the haltere no longer properly functions. (b) Dandelion seed fibres add drag to the insect body, thus increasing passive stability. (c) Inset: body orientation and flight trajectory of a fly with halteres disabled (left), showing a tumbling motion while falling downwards. When fibres are attached to a haltere-disabled insect, it is able to keep upright as it descends (right). Main figure: insects are released in air, and flight performance is assessed by measuring the trajectory angle with respect to the downward vertical. Distributions of flight angles for insects with halteres disabled (light grey) and insects with halteres disabled and with fibres attached (dark grey). (Online version in colour.)
Mentions: To offer further evidence that fruit flies rely on active control, we revisit classic experiments that disable the fast mechanical sensors of these insects [1,15,16]. As shown in figure 2a, the halteres of the fly are located below each wing and oscillate in flight, serving as gyroscopic sensors of body rotations. Here, we disable this sensory function by glueing the halteres to the abdomen and thereby preventing any oscillations. When released in still air, these sensor-disabled insects fall nearly straight down as indicated by the measured left trajectory in figure 2c. High-speed video shows that these flies are indeed flapping their wings at typical frequencies and amplitudes but that their body rapidly tumbles nonetheless, suggesting that a lack of orientational control undermines their flight. To quantify their flight performance, we release sensor-disabled flies from 1 m high and measure the radial distance these insects are able to travel. We then compute the flight angle as the inverse tangent of the ratio of the distance travelled to the initial drop height. A histogram of many trials is shown in light grey in figure 2c, and the typical flight trajectory angle near zero quantifies their poor flight performance.FigureĀ 2.

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