Flapping Aerial Vehicles
Aerial platforms based on a flapping wing design.

Goal: Design and manufacture an autonomous aerial vehicle capable of sustained flapping flight. Targeted weight and wingspan of the robot are ~1 g and 7-10 cm respectively. The platform is intended to be used for developing and testing control laws for the vehicle's position and orientation in space.

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. Missing any mechanical stops, the motion of this system is governed only by the dynamics of the wing, aerodynamic forces and torsional spring/damper torques at the wing's rotation axis. The design of the thorax of the robot is driven by several key guidelines. Individual control of each wing for simple body roll moment generation implies 2 separate PZT bending actuators. 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.

Benefits: Attempting to build an aerial vehicle on a 1 g size scale somewhat simplifies the manufacturing process. Furthermore, the proposed passive wing rotation design benefits from natural stability, mechanical simplicity, low controller bandwidth, and could potentially be realizable on a shorter time scale for specific applications. A working prototype can be utilized as a platform for testing controllability and developing control theory for such an under actuated system. Finally, as the manufacturing process is easily scalable, the final prototype can be simply scaled with slight modifications accounting for increased operating frequency and lower inertia.

Current Status: Per numerical optimization results and theoretical considerations the wing flapping frequency has been lowered to 40Hz from the previous 80Hz in favor of increased stroke and lower actuator stress levels. The 2nd prototype of the carbon fiber thorax is currently undergoing tests on an experimental rig for roll and pitch control, this is done in parallel with numerical simulations. Nature features large availability of species of flapping wing insects on the small scale, while fixed wing flyers dominate the larger scale. Reducing the size of the flapping wing platform is favorable as increased power density of the actuators and higher frequencies generally increase the lift/weight ratio of the robot. Thus, given that the carbon composites process is easily scalable, a 1/2 sized flapping robot is manufactured and is currently undergoing testing.

Videos: (newest to oldest)

• Flapping amplitude change achieved with tunable stiffness hinge wmv.

Members: Lindsey Hines

Past Members: Slava Arabagi, Robert Smith, Man Seong Kim


Papers:

• 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.
• V. Arabagi, B. Behkam, and M. Sitti, "Modeling of Stochastic Motion of Bacteria Propelled Spherical Micro-Beads", Journal of Applied Physics, 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.