Meeting Abstract

101.6  Sunday, Jan. 6  Agile airframes II: closing the loop on abdominal actuation COLMENARES, DJ*; DYHR, JP; MORGANSEN, KA; DANIEL, TL; Univ. of Washington; Univ. of Washington; Univ. of Washington; Univ. of Washington djc26@uw.edu

Flying organisms achieve flight stability by employing a multitude of control surfaces, most notably the wings. However, airframe deformations, such as abdominal motions in the hawk moth Manduca sexta, have recently been shown to play a significant role in stabilizing flight. We sought to determine the control potential of abdominal deflections using a closed-loop flight arena. Tethered moths controlled the velocity of a projected black bar with their abdominal angle. Image velocity varied according to the difference between the abdominal angle and the set point (relative to the average abdominal angle), scaled by a gain factor. Experimental trials were performed for a ten-fold range of gains at three different set points and consisted of 60s periods during which the moths attempted to stabilize the drifting bar. We measured performance as the percentage of trial time in which the animal stabilized image velocity below 5 °/s. The moths were capable of stabilizing the image for all experimental conditions, with the highest average performance (50%) occurring at the medium gain and the set point corresponding to the average abdominal angle. Poor performance (<50%) during low gain trials was characterized by steady state error, likely the result of the relatively low image velocities. For high gain trials, the decreased performance (<35%) was characterized by large abdominal oscillations. These results support an active and plastic role for the abdomen in flight control, but also tested the limits of the abdominal control circuit. Adaptation to the range of gains indicates that the controller is robust to changes in body dynamics, while changes in set point demonstrate the behavior is learned and not reflexive.