Research Papers

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

[+] Author and Article Information
Matt McDonald

Department of Mechanical Engineering, University of Delaware, Newark, DE 19716matthew.p.mcdonald@gmail.com

Sunil K. Agrawal

Department of Mechanical Engineering, University of Delaware, Newark, DE 19716agrawal@udel.edu

J. Mechanisms Robotics 2(2), 021012 (May 03, 2010) (6 pages) doi:10.1115/1.4001460 History: Received April 28, 2008; Revised October 12, 2009; Published May 03, 2010; Online May 03, 2010

The design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely light-weight designs that accomplish these motions of the wing, using just a single or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 1

Robotic flapper capable of 3DOF flapping and rotation generated using three independent servomotors. Mounted at the base of the wing is a six-axis force/torque sensor, Nano 17 from ATI Industrial Automation.

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Figure 2

Diagram of the actuated degrees of freedom of 3DOF flapping device

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Figure 3

A spherical 4R mechanism and its nomenclature

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Figure 4

The spherical 4R linkage with coupler extension

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Figure 5

The desired path in two views with arrows representing direction of travel. The short and long line segments protruding from the flap path designate the wing’s span-direction and chord-direction, respectively.

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Figure 6

The desired robotic flapping device path and the optimized spherical mechanism path overlaid in the optimized configuration

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Figure 7

Two views of the SolidWorks model for the spherical mechanism flapping device

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Figure 8

The complete spherical mechanism with no wing attached

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Figure 9

(a) The wing used in the experimental study. The wing spars are made from pultruded carbon fiber rods. The wing is covered in Mylar, and an aluminum base is used to allow mounting to the force-torque sensor. An identical uncovered wing was also used to gather inertial data. (b) (c) A typical curve for lift generated by the robotic flapping device over one complete cycle at 3.75 rad/s. (d) Comparison of average values for lift generated by each device at a variety of speeds. Error bars calculated from 10 cycles, representing one standard deviation.




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