Analysis of Roll Rotation Mechanism of a Butterfly for Development of a Small Flapping Robot

Abstract

In this paper, we examine the attitude recovering mechanism of a butterfly by focusing on roll rotation during flight and by developing a fluid solver which analyzes the air flow around the wing using a 3D high speed camera system. Micro aerial vehicles (MAVs) mimicking the flight mechanisms of insects have been developed in recent years. These robots are just a few centimeters in length and have sub-gram weight. However, the attitude and motion controls for such robots have not yet been achieved. The reason for this is that the generation mechanisms of lift and angular moment are still unclear. We clarify the attitude control mechanism of a butterfly by focusing on the pitch and roll rotations. Here we visualized the airflow around a butterfly by computational fluid dynamics which used 3D flight data calculated from 3D high speed camera images as boundary conditions. The results of the analysis showed that the pressure distributions on the wings were different for pitch and roll rotations. In a pitch rotation maneuver, the butterfly changed its pitch angle most significantly. In this case, the differential pressure was concentrated at the fore wings. The maximal reaction force on both sides of the wing and the average angular moment about the pitch axis were 200mN and -32 Nm