Flapping wing-based highly dynamic flight

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Small-scale flapping wing air vehicles present a large leap forward in agility, maneuverability and aerial acrobatic potential from their fixed and rotary wing counterparts. Inspiration comes from nature's dragonflies, hummingbirds, and flies which cannot only hover but also perform fast and precise maneuvers. We aim to design and manufacture an autonomous aerial vehicle capable of sustained flapping flight and ultimately similar feats. Our current targeted robot weight is around 3 g, though in the past we have worked on systems weighing less than 500 mg. In order to reduce weight and mechanism complexity, our flapping wing design is based on completely passive wing pitch reversal. The motion of the wing is governed only by the wing inertia, aerodynamic forces, and torsional spring/damper torques at the wing's rotation axis. The design of the robot body is driven by a few key ideas: individual control of each wing, weight minimization, and center of gravity positioning.

 

In our initial work our sub-gram system prototypes were driven by piezoelectric bending actuators and, given the need to control the wings independently, were configured so a single actuator was dedicated to each wing. To achieve body stability in flight we developed a spherical four-bar transmission mechanism that allows positioning of the center of mass below the lift producing wings. Several other design aspects were considered to stiffen the thorax body as well as achieve minimal coupling between the two wings.

 

Similarly, our latest prototypes have a single actuator per wing. However, instead of piezoelectrics, we use small geared pager motors. By avoiding the addition of a nonlinear transmission and directly mounting the wings to the gearbox output shaft we are able to maintain control over wing flapping angle, allowing the generation of roll and pitch body torques. With the addition of a spring in parallel the system can be driven at resonance, reducing the necessary power to flap and allowing the generation of enough lift for liftoff.

 

The resonant motor design is a very minimalist approach to flapping flight but one that should be capable of controlled hover. Not only is it comparatively simple to construct, overall weight is significantly reduced without the need for a surrounding body structure and additional transmission.

Robert Smith

Man Seong Kim

Slava Arabagi

Randall Kania

Lindsey Hines

David Colmenares

Selected Research Results and Papers

Liftoff of a Motor-driven, Flapping Wing Micro Aerial Vehicle Capable of Resonance

This study presents the design of a novel minimalist liftoff-capable flapping-wing microaerial vehicle. Two wings are each directly driven by a geared pager motor by utilizing an elastic element for energy recovery, resulting in a maximum lift-to-weight ratio of 1.4 at 10 Hz for the 2.7 g system. Separate directly driven wings allow the system to both resonate and control individual wing flapping angle, reducing necessary power consumption, as well as allowing the production of roll and pitch body torques. With a series of varied prototypes, system performance is examined with change in wing offset from center of rotation and elastic element stiffness. Prototype liftoff is demonstrated with open loop driving a tethered prototype without guide wires. A dynamic model of the system is adapted and compared with the prototype experimental results for later use in prototype optimization.

L. Hines, D. Campolo, M. Sitti, "Liftoff of a Motor-driven, Flapping Wing Micro Aerial Vehicle Capable of Resonance," IEEE Trans. on Robotics, vol. 30, no. 1, 2014, pp. 220 - 232.

Shape Memory Polymer-Based Flexure Stiffness Control in a Miniature Flapping-Wing Robot

An active flexural hinge has been developed and incorporated into the transmission of a prototype flapping-wing robot. The multilayered flexure, which is constructed from a shape memory polymer and a polyimide film, showed controllable stiffness under change in temperature. At room temperature, the flexure had a bending stiffness of 572 mN∑mm; when warmed to 70 ?C, the stiffness was 11 mN∑mm. The resulting single-wing flapping system demonstrated up to an 80% change in generated lift without modification of the waveform of the main driving piezoelectric actuator. Such active stiffness tunable flexure joints could be applied to any flexural miniature mobile robot and device mechanisms.

L. Hines, V. Arabagi, M. Sitti, "Shape Memory Polymer-Based Flexure Stiffness Control in a Miniature Flapping-Wing Robot," IEEE Trans. on Robotics, vol. 28, no. 4, 2012, pp. 987-990.

Selected Video

Motor-driven, Flapping Wing Micro Areal Vehicle

Liftoff of a Motor-driven, Flapping Wing Micro Aerial Vehicle Capable of Resonance

List of Publications

2015

 

Platform Design and Tethered Flight of a Motor-driven Flapping-wing System

L. Hines, D. Colmenares, M. Sitti

Conference on Robotics and Automation 2015, accepted.

 

 

2014

 

Liftoff of a Motor-Driven, Flapping-Wing Microaerial Vehicle Capable of Resonance

L Hines, D Campolo, M Sitti

IEEE Trans. on Robotics 30 (1), 220-232

 

 

2012

 

Shape memory polymer-based flexure stiffness control in a miniature flapping-wing robot

L Hines, V Arabagi, M Sitti

Robotics, IEEE Transactions on 28 (4), 987-990

 

 

2011

 

Free flight simulations and pitch and roll control experiments of a sub-gram flapping-flight micro aerial vehicle

LL Hines, V Arabagi, M Sitti

Robotics and Automation (ICRA), 2011 IEEE International Conference on, 1-7

 

 

A simulation and design tool for a passive rotation flapping wing mechanism

V Arabagi, L Hines, M Sitti

IEEE/ASME Transactions on Mechatronics 18 (2), 787-798

 

2010

 

Control performance simulation in the design of a flapping wing micro-aerial vehicle

LL Hines, V Arabagi, M Sitti

Intelligent Robots and Systems (IROS), 2010 IEEE/RSJ International ...

 

 

2008

 

Simulation and analysis of a passive pitch reversal flapping wing mechanism for an aerial robotic platform

V Arabagi, M Sitti

Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International ...