Flexible wing structures of simplified insect-sized flapping MAVs

One of challenges in building insect sized flapping MAVs (micro air vehicles) is to realize complex wing motions under severe design limitations in mass and size. In this paper, two examples of insect-sized flapping mechanism which reduces the mechanical complexity of the wings by utilizing flexible structures: One is a I-DOF butterfly model and the other is a 2DOF Diptera model. The butterfly model flew forward stably without any active control device. The flight speed depended on the wing flexibility determined by the wing venation pattern. It was found that the venation mimicking a real butterfly prevents excess feathering deformation of the wing, resulting in slow flight. In the 2-DOF Diptera model, wing pronation and supination were realized passively with a flexure film hinge at the wing root. Tethered flapping experiments showed that lift was maximized by optimizing the hinge stiffness. It was also demonstrated that corrugated cross sections of Dipteran wings are useful to increase spanwise stiffness of flexible artificial wings.