Fruit fly scale robots can hover longer with flapping wings than with spinning wings

• Published in: Journal of the Royal Society interface Vol. 13; no. 123; p. 20160730
• Main Authors: Hawkes, Elliot W., Lentink, David
• Format: Journal Article
• Language: English
• Published: England The Royal Society 01.10.2016
• Subjects: Animals; Aviation; Diptera; Flapping Wing; Hover; Life Sciences–Engineering interface; Micro Robot; Robotics; Spinning Wing; System Performance; Trade-Off; Wings, Animal; system performance; trade-off; hover; flapping wing; micro robot; spinning wing
• ISSN: 1742-5689; 1742-5662
• DOI: 10.1098/rsif.2016.0730

Hovering flies generate exceptionally high lift, because their wings generate a stable leading edge vortex. Micro flying robots with a similar wing design can generate similar high lift by either flapping or spinning their wings. While it requires less power to spin a wing, the overall efficiency depends also on the actuator system driving the wing. Here, we present the first holistic analysis to calculate how long a fly-inspired micro robot can hover with flapping versus spinning wings across scales. We integrate aerodynamic data with data-driven scaling laws for actuator, electronics and mechanism performance from fruit fly to hummingbird scales. Our analysis finds that spinning wings driven by rotary actuators are superior for robots with wingspans similar to hummingbirds, yet flapping wings driven by oscillatory actuators are superior at fruit fly scale. This crossover is driven by the reduction in performance of rotary compared with oscillatory actuators at smaller scale. Our calculations emphasize that a systems-level analysis is essential for trading-off flapping versus spinning wings for micro flying robots.