SCHOOL OF MECHANICAL ENGINEERING SEMINAR Monday, October 29, 2012 at 15:00 Wolfson Building of Mechanical Engineering, Room 206

Department of Physics, Cornell University, Ithaca, NY, USA

Flying insects manage to maintain aerodynamic stability despite the facts that flapping flight is inherently unstable and that they are constantly subject to mechanical perturbations, such as gusts of wind. To maintain stability against such perturbations, insects rely on fast and robust flight control mechanisms, which are poorly understood. Here, we directly study flight control in the fruit fly D. melanogaster by applying mechanical perturbations in mid-air and measuring the insects' correction maneuvers. On each fly we glue a small magnet, 1.5mm long, and use pulses of magnetic field to apply torque perturbations along the fly's roll axis. We then use high-speed filming and 3D hull-reconstruction to characterize the detailed kinematics of their correction maneuver and show how the flies fully recover from roll perturbations of up to 70o within 7-8 wing beats (30-40ms), which is faster than their visual response time. In addition, we study the dynamics of the maneuver by calculating the aerodynamic forces and torques the flies produces. Finally, we find which wing degrees-of-freedom the flies actuate during the correction and present a control mechanism that can explain the maneuver. These results have implications ranging from the neurobiological and structural mechanisms that underlie flight control to the design of flapping robots.

Figure 1: The recovery maneuver of a fruit fly Drosphila melanogaster from a roll perturbation while flying forward. The left column shows a side view with the corresponding time stamps and the right column shows the top view. The magnet glued on the back of the fly is seen in the side view. The perturbation torque was on between t=0 and 5ms, rotating the fly to its right. The fly reaches a maximum roll angle of ~70o at t=12.9ms (third row). The correction maneuver starts two wing beats after the perturbation started (second row): During the maneuver the right wing increases its stroke amplitude, while the left wing decreases its stroke amplitude and flips only at the middle of the stroke plane. This asymmetry continues for 4 wing beats, with the right wing moving faster thereby generating stronger aerodynamic forces. The fly fully corrects its roll angle 7-8 wing beats after the perturbation (bottom row).

Rock and Roll - How Do Flies Recover From Serial Stumbles?

Dr. Tsevi Beatus