Aerial platforms based on a flapping wing design.
We aim to design and manufacture an autonomous aerial vehicle capable of sustained flapping flight. Our current targeted robot weight is ~3 g, though in the past we have worked on systems weighing less than 500 mg.
Approach: 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 and basic concepts of flapping flight originated from studying the kinematics of nature's hummingbirds, butterflies, and flies. 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.
Current Status: Our current focus is on resonant, motor driven flapping wing systems. As our latest prototype is capable of liftoff and controlling torques, our next step is to close the loop and work towards controlled flight.
Videos: (newest to oldest)
- Open loop flight of the motor driven flapping wing system taken at 500fps (6MB wmv).
- Flapping amplitude change achieved with tunable stiffness hinge in the piezoelectric actuator driven system (1MB wmv).
Past Members: Slava Arabagi, Robert Smith, Man Seong Kim, Lindsey Hines
- L. Hines, D. Campolo, M. Sitti, "Liftoff of a Motor-driven, Flapping Wing Micro Aerial Vehicle Capable of Resonance," IEEE Trans. on Robotics, 2013, Accepted.
- 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.
- L. Hines, V. Arabagi, and M. Sitti, "Free Flight Simulations and Pitch and Roll Control Experiments of a Sub-gram Flapping-Flight Micro Aerial Vehicle", Proc. of the International Conference of Robotics and Automation, Shanghai, China, May 2011.
- V. Arabagi, L. Hines, and M. Sitti, "A Simulation and Design Tool for a Passive Rotation Flapping Wing Mechanism", Transactions on Mechatronics, 2011, under review.
- L. Hines, V. Arabagi, and M. Sitti, "Control Performance Simulation in the Design of a Flapping Wing MAV", Proc. of the IEEE/RSJ 2010 International Conference on Intelligent Robots and Systems, Taipei, Taiwan, Oct. 2010.
- V. Arabagi and M. Sitti, "Simulation and analysis of a passive pitch reversal flapping wing mechanism for an aerial robotic platform", IEEE/RSJ Int. Conf. On Robots and Systems, Nice, France, pp.1260-1265, Sept 2008.
- V. Arabagi and M. Sitti, "Simulation and Analysis of a Passive Pitch Reversal Flapping Wing Mechanism for an Aerial Robotic Platform", Proc. of the Adaptive Motion of Animals and Machines, Cleveland, OH, May 2008.