High-throughput measurement of free-flight kinematics in the dragonfly
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1
Janelia Farm / HHMI, United States
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2
Cornell University, Mechanical and Aerospace Engineering, United States
Dragonflies are aerial predators that capture small flying insects. They are highly specialized at intercepting prey and extremely maneuverable in flight. The guidance strategies underlying dragonfly prey capture, and the manner in which the four wings and head are controlled to implement these strategies, remain poorly understood. To explore these questions, we have built a system that allows a complete quantitative description of the kinematics of dragonfly flight, from take-off to prey capture. The primary advantages of our system over other methodologies for measuring free flight kinematics are (i) we are able to measure the entire duration of each prey capture event in a large spatial volume (~1s in duration, in a 2.5m3 volume), and (ii) data collection and analysis is high throughput – processing the dataset for an entire flight to obtain a rigid body model can be done in minutes, and data can be collected nearly continuously.
At the core of our system is an infrared camera array that can track custom sub-millimeter retroreflective markers to ~100 um precision. By attaching these small markers to each dragonfly in a carefully engineered configuration, we were able to measure 3D kinematics of the head, body and wings without significantly interfering with flight control. Eighteen cameras mounted on four walls simultaneously tracked the retroreflectors from multiple angles, allowing nearly continuous measurement of all marker positions regardless of dragonfly pitch, yaw, and roll. To construct a rigid-body dynamic model of a dragonfly, we developed procedures to locate the neck joint, wing hinges, axis of twist in the wings, and center of mass of the dragonfly. These 3D coordinates along with the marker data allowed us to determine the Euler angles for the orientation of the head and wings relative to the body, at 200 fps. Two grayscale Photron SA1 cameras running at 1000 fps, synchronized to the infrared camera system, were used to measure the fruit fly position and to verify the estimated location of each marker.
The retroreflective camera array was built in our indoor flight arena (ICN 2010, Salamanca), where dragonflies were allowed to forage freely with fruit flies as their primary prey. To the best of our knowledge, these are the first free-flight measurements of head and wing kinematics in an insect during a complex behavior. The 3D head orientation data allowed us to place the prey in dragonfly head-centered coordinates, and show the extent to which the dragonfly actively stabilizes the prey in the dorsal acute zone of its eye during foraging flights. We also observed fast stabilization of the head during (non-foraging) banking turns (rolls), as has been described in tethered animals. The body dynamics showed a directional take-off which was correlated to the interception course. In forward stable flight, rear wings lead the fore wings with a phase shift of ~70°. Wing asymmetries, including pitching and phasing differences, point to several mechanisms of steering; we are currently developing a computational aerodynamic model to test these hypotheses.
Keywords:
dragonfly,
flapping flight,
Flight control,
foraging,
high speed 3D tracking,
kinematics,
maneuvering dynamics,
prey capture
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for Participant Symposium)
Topic:
Sensorimotor Integration
Citation:
Lin
H,
Mischiati
M,
Melfi
J,
Herold
P,
Wang
J and
Leonardo
A
(2012). High-throughput measurement of free-flight kinematics in the dragonfly.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00320
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Received:
30 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Dr. Anthony Leonardo, Janelia Farm / HHMI, Ashburn, VA, 20147, United States, leonardoa@janelia.hhmi.org