A Review of Research on the Mechanical Design of Hoverable Flapping Wing Micro-Air Vehicles

Abstract

Most insects and hummingbirds can generate lift during both upstroke and downstroke with a nearly horizontal flapping stroke plane, and perform precise hovering flight. Further, most birds can utilize tails and muscles in wings to actively control the flight performance, while insects control their flight with muscles based on wing root along with wing’s passive deformation. Based on the above flight principles of birds and insects, Flapping Wing Micro Air Vehicles (FWMAVs) are classified as either bird-inspired or insect-inspired FWMAVs. In this review, the research achievements on mechanisms of insect-inspired, hoverable FWMAVs over the last ten years (2011–2020) are provided. We also provide the definition, function, research status and development prospect of hoverable FWMAVs. Then discuss it from three aspects: bio-inspiration, motor-driving mechanisms and intelligent actuator-driving mechanisms. Following this, research groups involved in insect-inspired, hoverable FWMAV research and their major achievements are summarized and classified in tables. Problems, trends and challenges about the mechanism are compiled and presented. Finally, this paper presents conclusions about research on mechanical structure, and the future is discussed to enable further research interests.

Untethered Flight of a 270 mg Microrobot Powered by Onboard Energy

“…The balloon was heat sealed by two film capacitors connected in series, generating buoyancy when filled with helium to overcome the robot's gravity (accounting for 95.59%), and providing a stored charge to supply energy for an electrostatic actuator. The electrostatic actuator was designed with transmission-free flapping, achieving passive [1,11,71,72] Festo products [15] (AirJelly, AirPenguins, and Air_ray), and specifications on commercial quadrotors such as Crazyflie, SKEYE Nano, Mesicopter, and DJI products. B) Mass versus COT data of the designed robots and living animals.…”

“…A) Mass versus wingspan data of the designed robots of this study and previous flying robots. The data in the graph come from the literature,[1,11,71,72] Festo products[15] (AirJelly, AirPenguins, and Air_ray), and specifications on commercial quadrotors such as Crazyflie, SKEYE Nano, Mesicopter, and DJI products. B) Mass versus COT data of the designed robots and living animals.…”

Inherently stable descending flight of a tailless flapping wing micro air vehicle by upward wing elevation

“…Much effort has been invested in understanding and modeling the aerodynamics of flapping flight 2,1,3,4 and in the development of aerial robots that mimic the flapping wing mechanism for lift production. [5][6][7][8][9][10] While conventional fixed wing and rotary wing drones are well suited for applications in large open areas, 11 insect-like flapping wing micro air vehicles and nano air vehicles (FWMAVs and FWNAVs) can be deployed in confined spaces that are difficult to navigate for other types of aerial vehicles. 12 Compared to fixed wing and rotary wing vehicles, flapping wing drone performance characteristics make them an attractive technology for applications that require downscaling.…”

Modeling and Analysis of a Simple Flexible Wing—Thorax System in Flapping-Wing Insects

“…However, the efficiency of conventional rotary or fixed-wing robotic vehicles is challenged at small-length scales (and hence, a low Reynolds numbers) because lift-generating aerodynamic forces are on the same order as viscous forces [ 4 ]. Many MAVs consequently use flapping wings, such as those employed by flying insects, to realize flight at small-length scales [ 5 ]. Nonetheless, the reduced payload capacity available to flapping-wing micro air vehicles (FWMAVs) introduces challenging design constraints.…”