High Speed Visual Insect Swarm Tracker (Hi-VISTA) used to identify the effects of confinement on individual insect flight

Individual insects flying in crowded assemblies perform complex aerial maneuvers by sensing and feeding back neighbor measurements to small changes in their wing motions. To understand the individual feedback rules that permit these fast, adaptive behaviors in group flight, a high-speed tracking system is needed capable of tracking both body motions and more subtle wing motion changes for multiple insects in simultaneous flight. This capability extends tracking beyond the previous focus on individual insects to multiple insects. This paper presents Hi-VISTA, which provides a capability to track wing and body motions of multiple insects using high speed cameras (9000 fps). Processing steps consist of automatic background identification, data association, hull reconstruction, segmentation, and feature measurement. To improve the biological relevance of laboratory experiments and develop a platform for interaction studies, this paper applies the Hi-VISTA measurement system to Apis mellifera foragers habituated to transit flights through a transparent tunnel. Binary statistical analysis (Welch's t-test, Cohen's d effect size) of 95 flight trajectories is presented, quantifying the differences between flights in an unobstructed tunnel and in a confined tunnel volume. The results indicate that body pitch angle, heading rate, flapping frequency, and vertical speed (heave) are all affected by confinement, and other flight variables show minor or statistically insignificant changes. These results form a baseline as swarm tracking and analysis begins to isolate the effects of neighbors from environment.

Pterosaurs evolved a muscular wing–body junction providing multifaceted flight performance benefits: Advanced aerodynamic smoothing, sophisticated wing root control, and wing force generation

Pterosaurs were the first vertebrate flyers and lived for over 160 million years. However, aspects of their flight anatomy and flight performance remain unclear. Using laser-stimulated fluorescence, we observed direct soft tissue evidence of a wing root fairing in a pterosaur, a feature that smooths out the wing–body junction, reducing associated drag, as in modern aircraft and flying animals. Unlike bats and birds, the pterosaur wing root fairing was unique in being primarily made of muscle rather than fur or feathers. As a muscular feature, pterosaurs appear to have used their fairing to access further flight performance benefits through sophisticated control of their wing root and contributions to wing elevation and/or anterior wing motion during the flight stroke. This study underscores the value of using new instrumentation to fill knowledge gaps in pterosaur flight anatomy and evolution.

A population of descending neurons that regulate the flight motor of Drosophila

Like many insect species, Drosophila melanogaster are capable of maintaining a stable flight trajectory for periods lasting up to several hours(1, 2). Because aerodynamic torque is roughly proportional to the fifth power of wing length(3), even small asymmetries in wing size require the maintenance of subtle bilateral differences in flapping motion to maintain a stable path. Flies can even fly straight after losing half of a wing, a feat they accomplish via very large, sustained kinematic changes to the both damaged and intact wings(4). Thus, the neural network responsible for stable flight must be capable of sustaining fine-scaled control over wing motion across a large dynamic range. In this paper, we describe an unusual type of descending neurons (DNg02) that project directly from visual output regions of the brain to the dorsal flight neuropil of the ventral nerve cord. Unlike most descending neurons, which exist as single bilateral pairs with unique morphology, there is a population of at least 15 DNg02 cell pairs with nearly identical shape. By optogenetically activating different numbers of DNg02 cells, we demonstrate that these neurons regulate wingbeat amplitude over a wide dynamic range via a population code. Using 2-photon functional imaging, we show that DNg02 cells are responsive to visual motion during flight in a manner that would make them well suited to continuously regulate bilateral changes in wing kinematics. Collectively, we have identified a critical set of DNs that provide the sensitivity and dynamic range required for flight control.

A novel flight style allowing the smallest featherwing beetles to excel

Flight speed generally correlates positively with animal body size [1]. Surprisingly, miniature featherwing beetles can fly at speeds and accelerations of insects three times as large [2]. We show here that this performance results from a previously unknown type of wing motion. Our experiment combines three-dimensional reconstructions of morphology and kinematics in one of the smallest insects, Paratuposa placentis (body length 395 μm). The flapping bristled wing follows a pronounced figure-eight loop that consists of subperpendicular up and down strokes followed by claps at stroke reversals, above and below the body. Computational analyses suggest a functional decomposition of the flapping cycle in two power half strokes producing a large upward force and two down-dragging recovery half strokes. In contrast to heavier membranous wings, the motion of bristled wings of the same size requires little inertial power. Muscle mechanical power requirements thus remain positive throughout the wing beat cycle, making elastic energy storage obsolete. This novel flight style evolved during miniaturization may compensate for costs associated with air viscosity and helps explain how extremely small insects preserved superb aerial performance during miniaturization. Incorporating this flight style in artificial flappers is a challenge for designers of micro aerial vehicles.

Dimensional analysis of spring-wing systems reveals performance metrics for resonant flapping-wing flight

Flapping-wing insects, birds and robots are thought to offset the high power cost of oscillatory wing motion by using elastic elements for energy storage and return. Insects possess highly resilient elastic regions in their flight anatomy that may enable high dynamic efficiency. However, recent experiments highlight losses due to damping in the insect thorax that could reduce the benefit of those elastic elements. We performed experiments on, and simulations of, a dynamically scaled robophysical flapping model with an elastic element and biologically relevant structural damping to elucidate the roles of body mechanics, aerodynamics and actuation in spring-wing energetics. We measured oscillatory flapping-wing dynamics and energetics subject to a range of actuation parameters, system inertia and spring elasticity. To generalize these results, we derive the non-dimensional spring-wing equation of motion and present variables that describe the resonance properties of flapping systems: N , a measure of the relative influence of inertia and aerodynamics, and K ^ , the reduced stiffness. We show that internal damping scales with N , revealing that dynamic efficiency monotonically decreases with increasing N . Based on these results, we introduce a general framework for understanding the roles of internal damping, aerodynamic and inertial forces, and elastic structures within all spring-wing systems.

Effect of Wing Corrugation on the Aerodynamic Efficiency of Two-Dimensional Flapping Wings

Many previous studies have shown that wing corrugation of an insect wing is only structurally beneficial in enhancing the wing’s bending stiffness and does not much help to improve the aerodynamic performance of flapping wings. This study uses two-dimensional computational fluid dynamics (CFD) in aiming to identify a proper wing corrugation that can enhance the aerodynamic performance of the KUBeetle, an insect-like flapping-wing micro air vehicle (MAV), which operates at a Reynolds number of less than 13,000. For this purpose, various two-dimensional corrugated wings were numerically investigated. The two-dimensional flapping wing motion was extracted from the measured three-dimensional wing kinematics of the KUBeetle at spanwise locations of r = (0.375 and 0.75)R. The CFD analysis showed that at both spanwise locations, the corrugations placed over the entire wing were not beneficial for improving aerodynamic efficiency. However, for the two-dimensional flapping wing at the spanwise location of r = 0.375R, where the wing experiences relatively high angles of attack, three specially designed wings with leading-edge corrugation showed higher aerodynamic performance than that of the non-corrugated smooth wing. The improvement is closely related to the flow patterns formed around the wings. Therefore, the proposed leading-edge corrugation is suggested for the inboard wing of the KUBeetle to enhance aerodynamic performance. The corrugation in the inboard wing may also be structurally beneficial.

The new concept of power transmission to the entomopter wings

The aim of this study is to discuss the design of the mechanism used for power transmission to the entomopter wings in order to perform a flapping motion and control the angle of attack of the wings. The study presents a kinematic diagram and a simulation model obtained in SolidWorks for the proposed mechanism, which includes a slotted link mechanism and a slider mechanism (with bilateral slider) that actuates the rocking lever of the wing. The simulation model allowed for observation of the system work and verification of the adopted kinematic assumptions. The comparative analysis showed that trajectories obtained from the both models are very similar. The correct operation of the proposed solution has been demonstrated by building a prototype of the mechanism and conducting experimental research. In the case of the application of the solution presented for the real object it is sufficient to choose the system parameters in order to properly reflect the living organism. The proposed mechanism is characterized by simplicity and offers opportunity for miniaturization while ensuring reliable work at reduced demand for power to drive the mechanism. A technological advantage of the presented solution is the use of only one component in order to perform flapping wing motion and change the angle of attack of the entomopter.

How to Fly

Energy expenditure of flight can be reduced by flight formation (echelon, V-shape). Birds make use of this, as well as of upwash/downwash effects due to wing motion. Flight details were studied empirically by human-led migrations of the Northern bald ibis. The human leaders flew in light glider devices, the birds carried light GPS recorders on their backs.