scholarly journals From flapping wings to underactuated fingers and beyond: a broad look to self-adaptive mechanisms

2010 ◽  
Vol 1 (1) ◽  
pp. 5-12 ◽  
Author(s):  
L. Birglen
Keyword(s):  
International Workshop ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Adaptive Mechanism ◽  
Current Increase ◽  
Adaptive Mechanisms ◽  
Original Application ◽  
Underactuated Finger ◽  
Self Adaptive

Abstract. In this paper, the author first reviews the different terminologies used in underactuated grasping and illustrates the current increase of activity on this topic. Then, the (probably) oldest known self-adaptive mechanism is presented and its performance as an underactuated finger is discussed. Its original application, namely a flapping wing, is also shown. Finally, it is proposed that the mechanisms currently used in underactuated grasping have actually other applications similarly to the previously discussed architecture could be used for both an underactuated finger and a flapping wing. This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010), 19 August 2010, Montréal, Canada.

scholarly journals Footprints of a flapping wing

2017 ◽  
Vol 818 ◽  
pp. 1-4 ◽  
Author(s):  
Jun Zhang
Keyword(s):  
Flow Pattern ◽  
External Force ◽  
Thrust Force ◽  
Flow Patterns ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Left Behind ◽  
Full Picture

Birds have to flap their wings to generate the needed thrust force, which powers them through the air. But how exactly do flapping wings create such force, and at what amplitude and frequency should they operate? These questions have been asked by many researchers. It turns out that much of the secret is hidden in the wake left behind the flapping wing. Exemplified by the study of Andersen et al. (J. Fluid Mech., vol. 812, 2017, R4), close examination of the flow pattern behind a flapping wing will inform us whether the wing is towed by an external force or able to generate a net thrust force by itself. Such studies are much like looking at the footprints of terrestrial animals as we infer their size and weight, figuring out their walking and running gaits. A map that displays the collection of flow patterns after a flapping wing, using flapping frequency and amplitude as the coordinates, offers a full picture of its flying ‘gaits’.

A Method to Avoid Singularity of the Planar Four-Bar Linkage by Means of Self-Adaptive Structure

2014 ◽  
Vol 709 ◽  
pp. 227-233
Author(s):  
Rui Qin Guo ◽  
Wei Hu ◽  
Juan Liu ◽  
Song Lin
Keyword(s):  
Adaptive Mechanism ◽  
Control Parameters ◽  
Singularity Problem ◽  
Practical Solution ◽  
Adaptive Structure ◽  
Vexed Question ◽  
Four Bar Linkage ◽  
Mechanism Theory ◽  
Intrinsic Characteristic ◽  
Self Adaptive

The singularity, namely, the output movement of the mechanism is uncertain due to kinematic bifurcation at the singular position, is the intrinsic characteristic of mechanism, resulting in movement out of control. To find a practical solution for this vexed question to make mechanism able to avoid its singular position is the greatest challenge in the field of mechanism. Based on the study of the planar four-bar linkage with singularity, the ideology of introducing self-adaptive mechanism theory into the solution of avoid singularity problem is firstly put forward in this paper. Using self-adaptive mechanism to complement the out of control parameters of singular position can make the mechanism have the ability to avoid singularity. Then the mechanism passes through the singular position smoothly with determined movement and load capability. Finally, the purpose of avoiding singularity is achieved.

Recent progress in flapping wings for micro aerial vehicle applications

2020 ◽  
pp. 095440622091742
Author(s):  
Naeem Haider ◽  
Aamer Shahzad ◽  
Muhammad Nafees Mumtaz Qadri ◽  
Syed Irtiza Ali Shah
Keyword(s):  
Leading Edge ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Structural Flexibility ◽  
Micro Aerial Vehicles ◽  
Flexible Wings ◽  
Performance Variables ◽  
Aerial Vehicles ◽  
Wide Range ◽  
Wing Geometry

Micro aerial vehicles using flapping wings are under investigation, as an alternative to fixed-wing and rotary-wing micro aerial vehicles. Such flapping-wing vehicles promise key potential advantages of high thrust, agility, and maneuverability, and have a wide range of applications. These applications include both military and commercial domains such as communication relay, search and rescue, visual reconnaissance, and field search. With the advancement in the computational sciences, developments in flapping-wing micro aerial vehicles have progressed exponentially. Such developments require a careful aerodynamic and aeroelastic design of the flapping wing. Therefore, aerodynamic tools are required to study such designs and configurations. In this paper, the role of several parameters is investigated, including the types of flapping wings, the effect of the kinematics and wing geometry (shape, configuration, and structural flexibility) on performance variables such as lift, drag, thrust, and efficiency in various modes of flight. Kinematic variables have a significant effect on the performance of the flapping wing. For instance, a high flap amplitude and pitch rotation, which supports the generation of the strong leading-edge vortex, generates higher thrust. Likewise, wing shape, configuration, and structural flexibility are shown to have a large impact on the performance of the flapping wing. The wing with optimum flexibility maximizes thrust where highly flexible wings lead to performance degradation due to change in the effective angle of attack. This study shows that the development of the flexible flapping wing with performance capabilities similar to those of natural fliers has not yet been achieved. Finally, opportunities for additional research in this field are recommended.

Induced Strain Actuation for Solid-State Ornithopters: An Aeroelastic Study

2018 ◽  
Author(s):  
Francis Hauris ◽  
Onur Bilgen
Keyword(s):  
Reynolds Number ◽  
Solid State ◽  
Aspect Ratio ◽  
Interaction Model ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Structural Behavior ◽  
Structure Interaction ◽  
Dynamic Motion ◽  
Lift And Drag

This paper investigates the dynamic aeroelastic behavior of strain actuated flapping wings with various geometries and boundary conditions. A fluid-structure interaction model of a plate-like flapping wing is developed. Assuming a chord Reynolds number of 100,000, the wing is harmonically actuated while varying parameters such as aspect ratio and wing root clamped percentage. Characteristic metrics for the dynamic motion, natural frequency, lift and drag are developed. These results are compared with purely structural behavior to understand the aeroelastic effects.

Four-Bar Linkage Mechanism for Insectlike Flapping Wings in Hover: Concept and an Outline of Its Realization

2005 ◽  
Vol 127 (4) ◽  
pp. 817-824 ◽  
Author(s):  
Rafał Z˙bikowski ◽  
Cezary Galin´ski ◽  
Christopher B. Pedersen
Keyword(s):  
Insect Flight ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Flapping Wings ◽  
Test Bed ◽  
Linkage Mechanism ◽  
Actual Design ◽  
Straight Line Mechanism ◽  
Four Bar Linkage ◽  
Air Vehicles

This paper describes the concept of a four-bar linkage mechanism for flapping wing micro air vehicles and outlines its design, implementation, and testing. Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (handheld), weighing 50–100 g, and are developed to reconnoiter in confined spaces (inside buildings, tunnels, etc.). For this application, insectlike flapping wings are an attractive solution and, hence, the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forward and backward. During this motion, the wing tip approximately traces a figure eight and the wing changes the angle of attack (pitching) significantly. The aim of the work described here was to design and build an insectlike flapping mechanism on a 150 mm scale. The main purpose was not only to construct a test bed for aeromechanical research on hover in this mode of flight, but also to provide a precursor design for a future flapping-wing MAV. The mechanical realization was to be based on a four-bar linkage combined with a spatial articulation. Two instances of idealized figure eights were considered: (i) Bernoulli’s lemniscate and (ii) Watt’s sextic. The former was found theoretically attractive, but impractical, while the latter was both theoretically and practically feasible. This led to a combination of Watt’s straight-line mechanism with a drive train utilizing a Geneva wheel and a spatial articulation. The actual design, implementation, and testing of this concept are briefly described at the end of the paper.

scholarly journals Isolation of a TRAIL Antagonist from the Serum of HIV-infected Patients

2011 ◽  
Vol 286 (41) ◽  
pp. 35742-35754 ◽  
Author(s):  
David J. Schnepple ◽  
Brett Shepard ◽  
Gary D. Bren ◽  
Nathan W. Cummins ◽  
Sekar Natesampillai ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Defense Mechanisms ◽  
Receptor Interaction ◽  
Adaptive Mechanism ◽  
Apoptosis Resistance ◽  
Host Interactions ◽  
Adaptive Mechanisms ◽  
Trail Receptors ◽  
Infected Cells ◽  
Selection Of

Virus-host interactions are characterized by the selection of adaptive mechanisms by which to evade pathogenic and defense mechanisms, respectively. In primary T cells infected with HIV, HIV infection up-regulates TNF-related apoptosis inducing ligand (TRAIL) and death-inducing TRAIL receptors, but blockade of TRAIL:TRAIL receptor interaction does not alter HIV-induced cell death. Instead, HIV infection results in a novel splice variant that we call TRAIL-short (TRAIL-s), which antagonizes TRAIL-R2. In HIV patients, plasma TRAIL-s concentration increases with increasing viral load and renders cells resistant to TRAIL-induced death. Knockdown of TRAIL-s abrogates this resistance. We propose that TRAIL-s is a novel adaptive mechanism of apoptosis resistance acquired by HIV-infected cells to avoid their elimination by TRAIL-dependent effector mechanism.

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