Air-to-land transitions: from wingless animals and plant seeds to shuttlecocks and bio-inspired robots

Abstract

Recent observations of wingless animals, including jumping nematodes, springtails, insects, and wingless vertebrates like geckos, snakes, and salamanders, have shown that their adaptations and body morphing are essential for rapid self-righting and controlled landing. These skills can reduce the risk of physical damage during collision, minimize recoil during landing, and allow for a quick escape response to minimize predation risk. The size, mass distribution, and speed of an animal determine its self-righting method, with larger animals depending on the conservation of angular momentum and smaller animals primarily using aerodynamic forces. Many animals falling through the air, from nematodes to salamanders, adopt a skydiving posture while descending. Similarly, plant seeds such as dandelions and samaras are able to turn upright in mid-air using aerodynamic forces and produce high decelerations. These aerial capabilities allow for a wide dispersal range, low-impact collisions, and effective landing and settling. Recently, small robots that can right themselves for controlled landings have been designed based on principles of aerial maneuvering in animals. Further research into the effects of unsteady flows on self-righting and landing in small arthropods, particularly those exhibiting explosive catapulting, could reveal how morphological features, flow dynamics, and physical mechanisms contribute to effective mid-air control. More broadly, studying apterygote (wingless insects) landing could also provide insight into the origin of insect flight. These research efforts have the potential to lead to the bio-inspired design of aerial micro-vehicles, sports projectiles, parachutes, and impulsive robots that can land upright in unsteady flow conditions.

A Sheet-Shaped Transforming Robot That Can Be Thrown from the Air

“…Bio-inspired technologies range from software to hardware [29]. Many biomimetic robots have also been proposed for robot movement from the air to land [30]. For a robot that imitates animals, some studies have mimicked the pitch control mechanisms of reptiles [31].…”

Wax “tails” enable planthopper nymphs to self-right midair and land on their feet

“…The benefits aerial righting range from landing in positions conducive to further jumps to achieving targeted landing [23,24,25]. Aerial righting, landing buffering (landing with legs toward the substrate to absorb impact) and resetting (achieving a favorable body position for subsequent jumps) are crucial for a successful jump cycle [26,27]. Moreover, eliminating the need for self-righting maneuvers after landing helps reduce predation risk, highlighting the evolutionary and functional importance of aerial righting [27].…”

“…The finite Reynolds numbers of these animals, coupled with the intricate dynamics of their body and wax structures, complicate identifying a precise mechanism for the wax tail's contribution to aerial righting. Unlike larger animals, such as geckos or cats, which utilize inertial forces via their tails or limbs [27], smaller organisms like dandelions, springtails, and planthoppers primarily rely on aerodynamic forces.…”