Stroke Plane Control for Longitudinal Stabilization of Hovering Flapping Wing Air Vehicles

Abstract

The stabilization of all the six longitudinal flight state variables using two control parameters, which are the stroke plane angle and the wingbeat frequency was studied. The MAV was numerically modeled in the form of nonlinear and time periodic equations of motion, and its unstable longitudinal flight dynamic characteristics are described by the linearized system equations. The source of the inherent instability in the longitudinal plane is investigated by interpreting the stability derivatives of the linearized system matrix; the nonnegative value of the stability derivative regarding the pitching moment due to the pitch attitude mainly causes unstable flight modes in the longitudinal plane. To stabilize all of the six longitudinal flight state variables, a feedback stabilization controller is designed and implemented on the nonlinear flight simulation. The linear quadratic regulator successfully generated the stabilizing control commands. A relative rotational motion of the stroke plane with respect to the body turns out to be one of the effective control efforts for the longitudinal stabilization of hovering flapping-wing MAVs. From this optimally designed closed-loop response, a simple control strategy was found that rotated the stroke plane angle just as much as the body pitch angle is rotated.