Limits...
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.

Show MeSH

Related in: MedlinePlus

Stability diagram for insect flight. Stability characteristics are plotted as a function of dimensionless forward and pitch damping time scales, TF/TI and TP/TI. The light blue region to the left of the black line corresponds to intrinsic stability. The region to the right is unstable, and the contours show the dimensionless instability growth time, TINST/TI. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4043156&req=5

RSIF20130237F4: Stability diagram for insect flight. Stability characteristics are plotted as a function of dimensionless forward and pitch damping time scales, TF/TI and TP/TI. The light blue region to the left of the black line corresponds to intrinsic stability. The region to the right is unstable, and the contours show the dimensionless instability growth time, TINST/TI. (Online version in colour.)

Mentions: These aspects of intrinsic stability can be summarized by the diagram shown in figure 4. Here, we have non-dimensionalized all relevant time scales by the inertial time TI. First, we plot the stability criterion of equation (3.5) as the heavy black curve. To the left of this stability boundary (blue region), the dimensionless damping time scales TF/TI and TP/TI are such that flight is intrinsically stable. To the right, flight is unstable and the coloured contours represent the dimensionless instability growth time scale, TINST/TI. Near the boundary, it grows slowly, and as one moves to the right on the diagram there is a broad region in which the instability grows a few times faster than the inertial time scale.FigureĀ 4.


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)

Stability diagram for insect flight. Stability characteristics are plotted as a function of dimensionless forward and pitch damping time scales, TF/TI and TP/TI. The light blue region to the left of the black line corresponds to intrinsic stability. The region to the right is unstable, and the contours show the dimensionless instability growth time, TINST/TI. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

RSIF20130237F4: Stability diagram for insect flight. Stability characteristics are plotted as a function of dimensionless forward and pitch damping time scales, TF/TI and TP/TI. The light blue region to the left of the black line corresponds to intrinsic stability. The region to the right is unstable, and the contours show the dimensionless instability growth time, TINST/TI. (Online version in colour.)
Mentions: These aspects of intrinsic stability can be summarized by the diagram shown in figure 4. Here, we have non-dimensionalized all relevant time scales by the inertial time TI. First, we plot the stability criterion of equation (3.5) as the heavy black curve. To the left of this stability boundary (blue region), the dimensionless damping time scales TF/TI and TP/TI are such that flight is intrinsically stable. To the right, flight is unstable and the coloured contours represent the dimensionless instability growth time scale, TINST/TI. Near the boundary, it grows slowly, and as one moves to the right on the diagram there is a broad region in which the instability grows a few times faster than the inertial time scale.FigureĀ 4.

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