Closed-loop control of constrained flapping wing micro air vehicles

Abstract

Micro air vehicles have a maximum dimension of 15 cm or less, which makes them ideal in confined spaces such as indoors, urban canyons, and caves. Flapping wing micro air vehicles have an additional advantage over fixed wing or rotary wing micro air vehicles in that the flapping motion mimics birds and insects, thus concealing their appearance while also providing benefits of unsteady aerodynamics. Considerable research has been invested in the areas of unsteady and low Reynolds number aerodynamics, as well as techniques to fabricate small scale prototypes. Control of these vehicles has been less studied, and most control techniques proposed have only been implemented within simulations without concern for power requirements, sensors and observers, or actual hardware demonstrations. In this work, power requirements while using a piezo-driven, resonant flapping wing control scheme, Bi-harmonic Amplitude and Bias Modulation, were studied. In addition, the power efficiency versus flapping frequency was studied and shown to be maximized while flapping at the piezo-driven system's resonance. Then prototype hardware of varying designs were used to capture the impact of a specific component of the flapping wing micro air vehicle, the passive rotation joint. The passive rotation joint was optimized through a range of different angle of attack stops and rotation joint stiffness to maximize lift and thrust force development. Optical tracking software was then developed to provide feedback information for use in closed-loop control experiments. Finally, closed-loop control of different constrained configurations were demonstrated using the resonant flapping Bi-harmonic Amplitude and Bias Modulation scheme with the optimized hardware. This work is important in the development and understanding of eventual free-flight capable flapping wing micro air vehicles