Dynamics and Control of a Minimally Actuated Biomimetic Vehicle: Part 1 - Aerodynamic Model (Postprint)

摘要

An aerodynamic model for the forces and moments acting on a minimally actuated flapping wing micro air vehicle (FWMAV) are derived from blade element theory. The proposed vehicle is similar to the Harvard RoboFly that accomplished the first takeoff of an insect scale flapping wing aircraft, except that it is equipped with independently actuated wings and the vehicle center-of-gravity can be manipulated for control purposes. Using a blade element-based approach, both instantaneous and cycle-averaged forces and moments are computed for a specific type of wing beat motion that enables nearly decoupled, multi-degree-of-freedom control of the aircraft. The wing positions are controlled using oscillators whose frequencies change once per wing beat cycle. A new technique is introduced, called Split-Cycle Constant- Period Frequency Modulation, that has the desirable property of providing a high level of control input decoupling for vehicles without active angle-of- attack control. Like the RoboFly, the wing angle-of-attack variation is passive by design, and is a function of the instantaneous angular velocity of the wing in the stroke plane. A control-oriented dynamic model of the vehicle is derived, which is based on a cycle-averaged representation of the forces and moments. Control derivatives are calculated and a cycle-averaged control law is designed that provides control over 5 degrees-of-freedom of the vehicle.