A robotic butterfly created by Japanese researchers tests the idea that the flight of the swallowtail butterfly can be created with simple flapping, with no "feathering" needed for feedback control.
(Robotic butterfly video)
From the abstract of the paper Forward flight of swallowtail butterfly with simple flapping motion published this week by Hiroto Tanaka and Isao Shimoyama, with support from both Harvard University and the University of Tokyo:
Unlike other flying insects, the wing motion of swallowtail butterflies is basically limited to flapping because their fore wings partly overlap their hind wings, structurally restricting the feathering needed for active control of aerodynamic force. Hence, it can be hypothesized that the flight of swallowtail butterflies is realized with simple flapping, requiring little feedback control of the feathering angle. To verify this hypothesis, we fabricated an artificial butterfly mimicking the wing motion and wing shape of a swallowtail butterfly and analyzed its flights using images taken with a high-speed video camera. The results demonstrated that stable forward flight could be realized without active feathering or feedback control of the wing motion. During the flights, the artificial butterfly's body moved up and down passively in synchronization with the flapping, and the artificial butterfly followed an undulating flight trajectory like an actual swallowtail butterfly. Without feedback control of the wing motion, the body movement is directly affected by change of aerodynamic force due to the wing deformation; the degree of deformation was determined by the wing venation. Unlike a veinless wing, a mimic wing with veins generated a much higher lift coefficient during the flapping flight than in a steady flow due to the large body motion.
Science fiction writers have long thought about mechanical insects and their possible uses. For example, in his 1980 novel Changeling, Roger Zelazny writes about a mechanized park complete with artificial butterflies:
He patted a dusty synthetic tree and crossed the unliving turf past holograms of swaying flowers to seat himself upon an orange plastic bench... Artificial butterflies darted along invisible beams... Concealed aerosols released the odors of flowers at regular intervals.
One of the fake butterflies passed too near, faltered and fell to the ground.
Scroll down for more stories in the same category. (Story submitted 5/26/2010)