How wing kinematics affect power requirements and aerodynamic force production in a robotic bat wing

2014 ◽  
Vol 9 (2) ◽  
pp. 025008 ◽  
Author(s):  
Joseph W Bahlman ◽  
Sharon M Swartz ◽  
Kenneth S Breuer
Keyword(s):  
Aerodynamic Force ◽  
Force Production ◽  
Wing Kinematics ◽  
Bat Wing

Effects of stretch receptor ablation on the optomotor control of lift in the hawkmothManduca sexta

2001 ◽  
Vol 204 (21) ◽  
pp. 3683-3691 ◽  
Author(s):  
Mark A. Frye
Keyword(s):  
Action Potentials ◽  
High Speed ◽  
Visual Cues ◽  
Aerodynamic Force ◽  
Video Recording ◽  
Force Production ◽  
Stretch Receptor ◽  
Flight Behavior ◽  
Wing Kinematics ◽  
Control Flight

SUMMARYIn insects, fast sensory feedback from specialized mechanoreceptors is integrated with guidance cues descending from the visual system to control flight behavior. A proprioceptive sensory organ found in both locusts and moths, the wing hinge stretch receptor, has been extensively studied in locusts for its powerful influence on the activity of flight muscle motoneurons and interneurons. The stretch receptor fires a high-frequency burst of action potentials near the top of each wingstroke and encodes kinematic variables such as amplitude and timing. Here, I describe the effects of stretch receptor ablation on the visual control of lift during flight in the hawkmoth Manduca sexta. Using a combination of extracellular muscle recordings, force and position measurements and high-speed video recording, I tracked power muscle activity, net vertical flight force (lift), abdomen deflection and wing kinematics in response to image motions of varying velocity during tethered flight in a wind tunnel. As a result of bilateral ablation of the wing hinge stretch receptors, visually evoked lift decreased to nearly one-third of that exhibited by intact animals. The phase and frequency of indirect power muscle action potentials and the patterns of abdominal deflection were unaffected; however, wingstroke amplitude was clearly reduced after ablation. Collectively, these results suggest that stretch receptor feedback is integrated with descending visual cues to control wing kinematics and the resultant aerodynamic force production during flight.

scholarly journals Deformable wing kinematics in the desert locust: how and why do camber, twist and topography vary through the stroke?

2008 ◽  
Vol 6 (38) ◽  
pp. 735-747 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
Flight Control ◽  
High Speed ◽  
Schistocerca Gregaria ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Force Production ◽  
Linear Increase ◽  
Trailing Edge ◽  
Wing Kinematics ◽  
Drag Ratio

Here, we present a detailed analysis of the wing kinematics and wing deformations of desert locusts ( Schistocerca gregaria , Forskål) flying tethered in a wind tunnel. We filmed them using four high-speed digital video cameras, and used photogrammetry to reconstruct the motion of more than 100 identified points. Whereas the hindwing motions were highly stereotyped, the forewing motions showed considerable variation, consistent with a role in flight control. Both wings were positively cambered on the downstroke. The hindwing was cambered through an ‘umbrella effect’ whereby the trailing edge tension compressed the radial veins during the downstroke. Hindwing camber was reversed on the upstroke as the wing fan corrugated, reducing the projected area by 30 per cent, and releasing the tension in the trailing edge. Both the wings were strongly twisted from the root to the tip. The linear decrease in incidence along the hindwing on the downstroke precisely counteracts the linear increase in the angle of attack that would otherwise occur in root flapping for an untwisted wing. The consequent near-constant angle of attack is reminiscent of the optimum for a propeller of constant aerofoil section, wherein a linear twist distribution allows each section to operate at the unique angle of attack maximizing the lift to drag ratio. This implies tuning of the structural, morphological and kinematic parameters of the hindwing for efficient aerodynamic force production.

scholarly journals The production of elevated flight force compromises manoeuvrability in the fruit fly Drosophila melanogaster

2001 ◽  
Vol 204 (4) ◽  
pp. 627-635 ◽  
Author(s):  
F.O. Lehmann ◽  
M.H. Dickinson
Keyword(s):  
Drosophila Melanogaster ◽  
Aerodynamic Force ◽  
Force Production ◽  
Fruit Fly ◽  
Mean Value ◽  
Fruit Flies ◽  
Force Coefficient ◽  
Stroke Frequency ◽  
Wing Kinematics ◽  
Stroke Amplitude

In this study, we have investigated how enhanced total flight force production compromises steering performance in tethered flying fruit flies, Drosophila melanogaster. The animals were flown in a closed-loop virtual-reality flight arena in which they modulated total flight force production in response to vertically oscillating visual patterns. By simultaneously measuring stroke amplitude and stroke frequency, we recorded the ability of each fly to modulate its wing kinematics at different levels of aerodynamic force production. At a flight force that exactly compensates body weight, the temporal deviations with which fruit flies vary their stroke amplitude and frequency are approximately 2.7 degrees and 4.8 Hz of their mean value, respectively. This variance in wing kinematics decreases with increasing flight force production, and at maximum force production fruit flies are restricted to a unique combination of stroke amplitude, stroke frequency and mean force coefficient. This collapse in the kinematic envelope during peak force production could greatly attenuate the manoeuvrability and stability of animals in free flight.

scholarly journals Operation of the alula as an indicator of gear change in hoverflies

2011 ◽  
Vol 9 (71) ◽  
pp. 1194-1207 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Angular Acceleration ◽  
The State ◽  
The Body ◽  
Kinematic Parameters ◽  
Wing Kinematics ◽  
Change Mechanism ◽  
The Third ◽  
Gear Change

The alula is a hinged flap found at the base of the wings of most brachyceran Diptera. The alula accounts for up to 10 per cent of the total wing area in hoverflies (Syrphidae), and its hinged arrangement allows the wings to be swept back over the thorax and abdomen at rest. The alula is actuated via the third axillary sclerite, which is a component of the wing hinge that is involved in wing retraction and control. The third axillary sclerite has also been implicated in the gear change mechanism of flies. This mechanism allows rapid switching between different modes of wing kinematics, by imposing or removing contact with a mechanical stop limiting movement of the wing during the lower half of the downstroke. The alula operates in two distinct states during flight—flipped or flat—and we hypothesize that its state indicates switching between different flight modes. We used high-speed digital video of free-flying hoverflies ( Eristalis tenax and Eristalis pertinax ) to investigate whether flipping of the alula was associated with changes in wing and body kinematics. We found that alula state was associated with different distributions of multiple wing kinematic parameters, including stroke amplitude, stroke deviation angle, downstroke angle of incidence and timing of supination. Changes in all of these parameters have previously been linked to gear change in flies. Symmetric flipping of the alulae was associated with changes in the symmetric linear acceleration of the body, while asymmetric flipping of the alulae was associated with asymmetric angular acceleration of the body. We conclude that the wings produce less aerodynamic force when the alula is flipped, largely as a result of the accompanying changes in wing kinematics. The alula changes state at mid-downstroke, which is the point at which the gear change mechanism is known to come into effect. This transition is accompanied by changes in the other wing kinematic parameters. We therefore find that the state of the alula is linked to the same parameters as are affected by the gear change mechanism. We conclude that the state of the alula does indeed indicate the operation of different flight modes in Eristalis , and infer that a likely mechanism for these changes in flight mode is the gear change mechanism.

Deformable Blade Element and Unsteady Vortex Lattice Fluid-Structure Interaction Modeling of a 2D Flapping Wing

2020 ◽  
Author(s):  
Joseph Reade ◽  
Mark A. Jankauski
Keyword(s):  
Vortex Lattice ◽  
Normal Force ◽  
Aerodynamic Force ◽  
Fluid Structure Interaction ◽  
Force Production ◽  
Flapping Wing ◽  
Energetic Efficiency ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Blade Element

Abstract Flapping insect wings experience appreciable deformation due to aerodynamic and inertial forces. This deformation is believed to benefit the insect’s aerodynamic force production as well as energetic efficiency. However, the fluid-structure interaction (FSI) models used to estimate wing deformations are often computationally demanding and are therefore challenged by parametric studies. Here, we develop a simple FSI model of a flapping wing idealized as a two-dimensional pitching-plunging airfoil. Using the Lagrangian formulation, we derive the reduced-order structural framework governing wing’s elastic deformation. We consider two fluid models: quasi-steady Deformable Blade Element Theory (DBET) and Unsteady Vortex Lattice Method (UVLM). DBET is computationally economical but does not provide insight into the flow structure surrounding the wing, whereas UVLM approximates flows but requires more time to solve. For simple flapping kinematics, DBET and UVLM produce similar estimates of the aerodynamic force normal to the surface of a rigid wing. More importantly, when the wing is permitted to deform, DBET and UVLM agree well in predicting wingtip deflection and aerodynamic normal force. The most notable difference between the model predictions is a roughly 20° phase difference in normal force. DBET estimates wing deformation and force production approximately 15 times faster than UVLM for the parameters considered, and both models solve in under a minute when considering 15 flapping periods. Moving forward, we will benchmark both low-order models with respect to high fidelity computational fluid dynamics coupled to finite element analysis, and assess the agreement between DBET and UVLM over a broader range of flapping kinematics.

scholarly journals Reconstructing Full-Field Flapping Wing Dynamics from Sparse Measurements

2020 ◽  
Author(s):  
William Johns ◽  
Lisa Davis ◽  
Mark Jankauski
Keyword(s):  
Aerodynamic Force ◽  
Force Production ◽  
Energetic Efficiency ◽  
Reconstruction Technique ◽  
Reconstruction Method ◽  
Full Field ◽  
Insect Wing ◽  
Insect Wings ◽  
Flying Insects ◽  
Sparse Measurements

AbstractFlapping insect wings deform during flight. This deformation benefits the insect’s aerodynamic force production as well as energetic efficiency. However, it is challenging to measure wing displacement field in flying insects. Many points must be tracked over the wing’s surface to resolve its instantaneous shape. To reduce the number of points one is required to track, we propose a physics-based reconstruction method called System Equivalent Reduction Expansion Processes (SEREP) to estimate wing deformation and strain from sparse measurements. Measurement locations are determined using a Weighted Normalized Modal Displacement (NMD) method. We experimentally validate the reconstruction technique by flapping a paper wing from 5-9 Hz with 45° and measuring strain at three locations. Two measurements are used for the reconstruction and the third for validation. Strain reconstructions had a maximal error of 30% in amplitude. We extend this methodology to a more realistic insect wing through numerical simulation. We show that wing displacement can be estimated from sparse displacement or strain measurements, and that additional sensors spatially average measurement noise to improve reconstruction accuracy. This research helps overcome some of the challenges of measuring full-field dynamics in flying insects and provides a framework for strain-based sensing in insect-inspired flapping robots.

scholarly journals THE LOCUST TEGULA: SIGNIFICANCE FOR FLIGHT RHYTHM GENERATION, WING MOVEMENT CONTROL AND AERODYNAMIC FORCE PRODUCTION

1993 ◽  
Vol 182 (1) ◽  
pp. 229-253 ◽  
Author(s):  
H Wolf
Keyword(s):  
Flight Control ◽  
Aerodynamic Force ◽  
Motor Pattern ◽  
Vertical Component ◽  
Sense Organ ◽  
Force Production ◽  
Movement Control ◽  
Rhythm Generation ◽  
Wing Movement ◽  
Before And After

The tegula, a complex sense organ associated with the wing base of the locust, plays an important role in the generation of the flight motor pattern. Here its function in the control of wing movement and aerodynamic force production is described.The vertical component of forewing movement was monitored while recording intracellularly from flight motoneurones during stationary flight. First, in accordance with previous electrophysiological results, stimulation of hindwing tegula afferents was found to reset the wingstroke to the elevation phase in a well-coordinated manner. Second, recordings made before and after removal of fore- and hindwing tegulae were compared. This comparison demonstrated that the delayed onset of elevator motoneurone activity caused by tegula removal is accompanied by a corresponding delay in the upstroke movement of the wings.The consequences of this delayed upstroke for aerodynamic force production were investigated by monitoring wing movements and lift generation simultaneously. A marked decrease in net lift generation was observed following tegula removal. Recordings of wing pronation indicate that this decrease in lift is primarily due to the delayed upstroke movement - that is, to a delay of the wings near the aerodynamically unfavourable downstroke position.It is concluded that the tegula of the locust hindwing signals to the nervous system the impending completion of the wing downstroke and allows initiation of the upstroke movement immediately after the wings have reached the lower reversal point of the wingstroke. The functional significance of tegula feedback and central rhythm generation for locust flight control are discussed.

scholarly journals Three-dimensional wing structure attenuates aerodynamic efficiency in flapping fly wings

2020 ◽  
Vol 17 (164) ◽  
pp. 20190804 ◽  
Author(s):  
Thomas Engels ◽  
Henja-Niniane Wehmann ◽  
Fritz-Olaf Lehmann
Keyword(s):  
Aerodynamic Force ◽  
Three Dimensional ◽  
Force Production ◽  
Reynolds Numbers ◽  
Dimensional Structure ◽  
Micro Computed Tomography ◽  
Venation Pattern ◽  
Aerodynamic Pressure ◽  
Inertial Loading ◽  
External Forces

The aerial performance of flying insects ultimately depends on how flapping wings interact with the surrounding air. It has previously been suggested that the wing's three-dimensional camber and corrugation help to stiffen the wing against aerodynamic and inertial loading during flapping motion. Their contribution to aerodynamic force production, however, is under debate. Here, we investigated the potential benefit of three-dimensional wing shape in three different-sized species of flies using models of micro-computed tomography-scanned natural wings and models in which we removed either the wing's camber, corrugation, or both properties. Forces and aerodynamic power requirements during root flapping were derived from three-dimensional computational fluid dynamics modelling. Our data show that three-dimensional camber has no benefit for lift production and attenuates Rankine–Froude flight efficiency by up to approximately 12% compared to a flat wing. Moreover, we did not find evidence for lift-enhancing trapped vortices in corrugation valleys at Reynolds numbers between 137 and 1623. We found, however, that in all tested insect species, aerodynamic pressure distribution during flapping is closely aligned to the wing's venation pattern. Altogether, our study strongly supports the assumption that the wing's three-dimensional structure provides mechanical support against external forces rather than improving lift or saving energetic costs associated with active wing flapping.

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