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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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Control requirements for hovering insects, hummingbirds and flapping-wing robots. (a) Insects of varying size whose reaction time has been measured or estimated: fruit fly (typical body length 2.7 mm), honeybee (16 mm) and hawkmoth (46 mm). (b) Insects with unusual damping characteristics. The viscous drag on the body of the tiny wasp (0.6 mm) is significant, the mosquito (4.4 mm) flies with its long legs extended and the woolly aphid (3.2 mm) has a fibrous coat. (c) Robots with different stabilization strategies: Harvard robot (15 mm) is externally stabilized with wire guides; Cornell robot (220 mm) has large sails; Mentor robot (360 mm) uses sensory feedback control. (d) Reaction time needed to stabilize flight for hovering animals (circles) and robots (squares). Reaction time is known for the fruit fly, honeybee and hawkmoth (filled circles) and predicted for other flyers (open symbols). Predictions are determined by the rule of thumb that reactions must be six times faster than the instability, with variations within the grey band due to differences in the unplotted parameter TF/TI. (Online version in colour.)
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RSIF20130237F7: Control requirements for hovering insects, hummingbirds and flapping-wing robots. (a) Insects of varying size whose reaction time has been measured or estimated: fruit fly (typical body length 2.7 mm), honeybee (16 mm) and hawkmoth (46 mm). (b) Insects with unusual damping characteristics. The viscous drag on the body of the tiny wasp (0.6 mm) is significant, the mosquito (4.4 mm) flies with its long legs extended and the woolly aphid (3.2 mm) has a fibrous coat. (c) Robots with different stabilization strategies: Harvard robot (15 mm) is externally stabilized with wire guides; Cornell robot (220 mm) has large sails; Mentor robot (360 mm) uses sensory feedback control. (d) Reaction time needed to stabilize flight for hovering animals (circles) and robots (squares). Reaction time is known for the fruit fly, honeybee and hawkmoth (filled circles) and predicted for other flyers (open symbols). Predictions are determined by the rule of thumb that reactions must be six times faster than the instability, with variations within the grey band due to differences in the unplotted parameter TF/TI. (Online version in colour.)

Mentions: In figure 7a–c, we highlight some animals and machines of varying size and shape, and in figure 2d we summarize the stability and control properties of all the flyers tabulated above. In addition to the fruit fly, the honeybee and hawkmoth are important case studies because the flight reaction times of these insects have been measured or estimated. For the honeybee, the reaction time was determined by measuring when compensatory wing motions were induced after a gust perturbation [60]. For the hawkmoth, the allowable delay was estimated in computer simulations of free flight [61]. These insects are represented by filled circles in figure 7d, and indeed these data are consistent with the control law that reactions are approximately six times faster than the instability. Thus, these insects have a similar control performance to that of the fruit fly despite their different control systems. In particular, neither the bee nor the moth have halteres, and the hawkmoth probably relies on its antennae for flight stabilization [62]. We are not aware of a study that has identified the relevant sensors for the honeybee.Figure 7.


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)

Control requirements for hovering insects, hummingbirds and flapping-wing robots. (a) Insects of varying size whose reaction time has been measured or estimated: fruit fly (typical body length 2.7 mm), honeybee (16 mm) and hawkmoth (46 mm). (b) Insects with unusual damping characteristics. The viscous drag on the body of the tiny wasp (0.6 mm) is significant, the mosquito (4.4 mm) flies with its long legs extended and the woolly aphid (3.2 mm) has a fibrous coat. (c) Robots with different stabilization strategies: Harvard robot (15 mm) is externally stabilized with wire guides; Cornell robot (220 mm) has large sails; Mentor robot (360 mm) uses sensory feedback control. (d) Reaction time needed to stabilize flight for hovering animals (circles) and robots (squares). Reaction time is known for the fruit fly, honeybee and hawkmoth (filled circles) and predicted for other flyers (open symbols). Predictions are determined by the rule of thumb that reactions must be six times faster than the instability, with variations within the grey band due to differences in the unplotted parameter TF/TI. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

RSIF20130237F7: Control requirements for hovering insects, hummingbirds and flapping-wing robots. (a) Insects of varying size whose reaction time has been measured or estimated: fruit fly (typical body length 2.7 mm), honeybee (16 mm) and hawkmoth (46 mm). (b) Insects with unusual damping characteristics. The viscous drag on the body of the tiny wasp (0.6 mm) is significant, the mosquito (4.4 mm) flies with its long legs extended and the woolly aphid (3.2 mm) has a fibrous coat. (c) Robots with different stabilization strategies: Harvard robot (15 mm) is externally stabilized with wire guides; Cornell robot (220 mm) has large sails; Mentor robot (360 mm) uses sensory feedback control. (d) Reaction time needed to stabilize flight for hovering animals (circles) and robots (squares). Reaction time is known for the fruit fly, honeybee and hawkmoth (filled circles) and predicted for other flyers (open symbols). Predictions are determined by the rule of thumb that reactions must be six times faster than the instability, with variations within the grey band due to differences in the unplotted parameter TF/TI. (Online version in colour.)
Mentions: In figure 7a–c, we highlight some animals and machines of varying size and shape, and in figure 2d we summarize the stability and control properties of all the flyers tabulated above. In addition to the fruit fly, the honeybee and hawkmoth are important case studies because the flight reaction times of these insects have been measured or estimated. For the honeybee, the reaction time was determined by measuring when compensatory wing motions were induced after a gust perturbation [60]. For the hawkmoth, the allowable delay was estimated in computer simulations of free flight [61]. These insects are represented by filled circles in figure 7d, and indeed these data are consistent with the control law that reactions are approximately six times faster than the instability. Thus, these insects have a similar control performance to that of the fruit fly despite their different control systems. In particular, neither the bee nor the moth have halteres, and the hawkmoth probably relies on its antennae for flight stabilization [62]. We are not aware of a study that has identified the relevant sensors for the honeybee.Figure 7.

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