51
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Beatus T, Guckenheimer JM, Cohen I. Controlling roll perturbations in fruit flies. J R Soc Interface 2015; 12:20150075. [PMID: 25762650 PMCID: PMC4387536 DOI: 10.1098/rsif.2015.0075] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 02/16/2015] [Indexed: 11/12/2022] Open
Abstract
Owing to aerodynamic instabilities, stable flapping flight requires ever-present fast corrective actions. Here, we investigate how flies control perturbations along their body roll angle, which is unstable and their most sensitive degree of freedom. We glue a magnet to each fly and apply a short magnetic pulse that rolls it in mid-air. Fast video shows flies correct perturbations up to 100° within 30 ± 7 ms by applying a stroke-amplitude asymmetry that is well described by a linear proportional-integral controller. For more aggressive perturbations, we show evidence for nonlinear and hierarchical control mechanisms. Flies respond to roll perturbations within 5 ms, making this correction reflex one of the fastest in the animal kingdom.
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Affiliation(s)
- Tsevi Beatus
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
| | | | - Itai Cohen
- Department of Physics, Cornell University, Ithaca, NY 14853, USA
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52
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Fuller SB, Karpelson M, Censi A, Ma KY, Wood RJ. Controlling free flight of a robotic fly using an onboard vision sensor inspired by insect ocelli. J R Soc Interface 2015; 11:20140281. [PMID: 24942846 DOI: 10.1098/rsif.2014.0281] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Scaling a flying robot down to the size of a fly or bee requires advances in manufacturing, sensing and control, and will provide insights into mechanisms used by their biological counterparts. Controlled flight at this scale has previously required external cameras to provide the feedback to regulate the continuous corrective manoeuvres necessary to keep the unstable robot from tumbling. One stabilization mechanism used by flying insects may be to sense the horizon or Sun using the ocelli, a set of three light sensors distinct from the compound eyes. Here, we present an ocelli-inspired visual sensor and use it to stabilize a fly-sized robot. We propose a feedback controller that applies torque in proportion to the angular velocity of the source of light estimated by the ocelli. We demonstrate theoretically and empirically that this is sufficient to stabilize the robot's upright orientation. This constitutes the first known use of onboard sensors at this scale. Dipteran flies use halteres to provide gyroscopic velocity feedback, but it is unknown how other insects such as honeybees stabilize flight without these sensory organs. Our results, using a vehicle of similar size and dynamics to the honeybee, suggest how the ocelli could serve this role.
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Affiliation(s)
- Sawyer B Fuller
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Michael Karpelson
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Andrea Censi
- Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA 02138, USA
| | - Kevin Y Ma
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - Robert J Wood
- School of Engineering and Applied Sciences and the Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
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53
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Whitehead SC, Beatus T, Canale L, Cohen I. Pitch perfect: how fruit flies control their body pitch angle. J Exp Biol 2015; 218:3508-19. [DOI: 10.1242/jeb.122622] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 09/03/2015] [Indexed: 11/20/2022]
Abstract
Flapping insect flight is a complex and beautiful phenomenon that relies on fast, active control mechanisms to counter aerodynamic instability. To directly investigate how freely-flying D. melanogaster control their body pitch angle against such instability, we perturb them using impulsive mechanical torques and film their corrective maneuvers with high-speed video. Combining experimental observations and numerical simulation, we find that flies correct for pitch deflections of up to 40° in 29±8 ms by bilaterally modulating their wings' front-most stroke angle in a manner well-described by a linear proportional-integral (PI) controller. Flies initiate this corrective process only 10±2 ms after the perturbation onset, indicating that pitch stabilization involves a fast reflex response. Remarkably, flies can also correct for very large-amplitude pitch perturbations–greater than 150°–providing a regime in which to probe the limits of the linear-response framework. Together with previous studies regarding yaw and roll control, our results on pitch show that flies' stabilization of each of these body angles is consistent with PI control
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Affiliation(s)
| | - Tsevi Beatus
- Department of Physics, Cornell University, Ithaca, New York, 14853, USA
| | - Luca Canale
- Département de Mécanique, École Polytechnique, 911128, Palaiseau, France
| | - Itai Cohen
- Department of Physics, Cornell University, Ithaca, New York, 14853, USA
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55
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Cowan NJ, Ankarali MM, Dyhr JP, Madhav MS, Roth E, Sefati S, Sponberg S, Stamper SA, Fortune ES, Daniel TL. Feedback control as a framework for understanding tradeoffs in biology. Integr Comp Biol 2014; 54:223-37. [PMID: 24893678 DOI: 10.1093/icb/icu050] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Control theory arose from a need to control synthetic systems. From regulating steam engines to tuning radios to devices capable of autonomous movement, it provided a formal mathematical basis for understanding the role of feedback in the stability (or change) of dynamical systems. It provides a framework for understanding any system with regulation via feedback, including biological ones such as regulatory gene networks, cellular metabolic systems, sensorimotor dynamics of moving animals, and even ecological or evolutionary dynamics of organisms and populations. Here, we focus on four case studies of the sensorimotor dynamics of animals, each of which involves the application of principles from control theory to probe stability and feedback in an organism's response to perturbations. We use examples from aquatic (two behaviors performed by electric fish), terrestrial (following of walls by cockroaches), and aerial environments (flight control by moths) to highlight how one can use control theory to understand the way feedback mechanisms interact with the physical dynamics of animals to determine their stability and response to sensory inputs and perturbations. Each case study is cast as a control problem with sensory input, neural processing, and motor dynamics, the output of which feeds back to the sensory inputs. Collectively, the interaction of these systems in a closed loop determines the behavior of the entire system.
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Affiliation(s)
- Noah J Cowan
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Mert M Ankarali
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Jonathan P Dyhr
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Manu S Madhav
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Eatai Roth
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Shahin Sefati
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Simon Sponberg
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Sarah A Stamper
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Eric S Fortune
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
| | - Thomas L Daniel
- *Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biology, University of Washington, Seattle, WA 98195, USA; Department of Biological Sciences, New Jersey Institute of Technology, Newark, NJ 07102, USA
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57
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Ristroph L, Childress S. Stable hovering of a jellyfish-like flying machine. J R Soc Interface 2014; 11:20130992. [PMID: 24430122 PMCID: PMC3899867 DOI: 10.1098/rsif.2013.0992] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/18/2013] [Indexed: 11/12/2022] Open
Abstract
Ornithopters, or flapping-wing aircraft, offer an alternative to helicopters in achieving manoeuvrability at small scales, although stabilizing such aerial vehicles remains a key challenge. Here, we present a hovering machine that achieves self-righting flight using flapping wings alone, without relying on additional aerodynamic surfaces and without feedback control. We design, construct and test-fly a prototype that opens and closes four wings, resembling the motions of swimming jellyfish more so than any insect or bird. Measurements of lift show the benefits of wing flexing and the importance of selecting a wing size appropriate to the motor. Furthermore, we use high-speed video and motion tracking to show that the body orientation is stable during ascending, forward and hovering flight modes. Our experimental measurements are used to inform an aerodynamic model of stability that reveals the importance of centre-of-mass location and the coupling of body translation and rotation. These results show the promise of flapping-flight strategies beyond those that directly mimic the wing motions of flying animals.
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Affiliation(s)
- Leif Ristroph
- Applied Math Lab, Courant Institute, New York University, 251 Mercer St., New York, NY 10012, USA
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58
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Ravi S, Crall JD, Fisher A, Combes SA. Rolling with the flow: bumblebees flying in unsteady wakes. ACTA ACUST UNITED AC 2013; 216:4299-309. [PMID: 24031057 DOI: 10.1242/jeb.090845] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Our understanding of how variable wind in natural environments affects flying insects is limited because most studies of insect flight are conducted in either smooth flow or still air conditions. Here, we investigate the effects of structured, unsteady flow (the von Karman vortex street behind a cylinder) on the flight performance of bumblebees (Bombus impatiens). Bumblebees are 'all-weather' foragers and thus frequently experience variable aerial conditions, ranging from fully mixed, turbulent flow to unsteady, structured vortices near objects such as branches and stems. We examined how bumblebee flight performance differs in unsteady versus smooth flow, as well as how the orientation of unsteady flow structures affects their flight performance, by filming bumblebees flying in a wind tunnel under various flow conditions. The three-dimensional flight trajectories and orientations of bumblebees were quantified in each of three flow conditions: (1) smooth flow, (2) the unsteady wake of a vertical cylinder (inducing strong lateral disturbances) and (3) the unsteady wake of a horizontal cylinder (inducing strong vertical disturbances). In both unsteady conditions, bumblebees attenuated the disturbances induced by the wind quite effectively, but still experienced significant translational and rotational fluctuations as compared with flight in smooth flow. Bees appeared to be most sensitive to disturbance along the lateral axis, displaying large lateral accelerations, translations and rolling motions in response to both unsteady flow conditions, regardless of orientation. Bees also displayed the greatest agility around the roll axis, initiating voluntary casting maneuvers and correcting for lateral disturbances mainly through roll in all flow conditions. Both unsteady flow conditions reduced the upstream flight speed of bees, suggesting an increased cost of flight in unsteady flow, with potential implications for foraging patterns and colony energetics in natural, variable wind environments.
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Affiliation(s)
- Sridhar Ravi
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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