Dynamic stability of a hawkmoth-scale flapping-wing micro air vehicle during forward flight

Abstract

This study investigates dynamic stability during forward flight of a hawkmoth-scale Flapping-wing Micro Air Vehicle (FWMAV). Dynamic modes in the longitudinal and lateral planes of motion during forward flight are identified by Eigen mode analyses from the author’s previous work, and these dynamic responses from a linearized system model are compared with the responses obtained by direct time integrations of nonlinear multibody dynamic equations of motion. The results show that the forward flight of FWMAV is unstable due to an unstable longitudinal oscillatory mode (forward/backward motion coupled with in-phase pitching motion) and a marginally stable lateral oscillatory mode (sideslip motion coupled with out-of-phase roll and in-phase yaw motion). A comparison between the linear and fully nonlinear multibody model shows that the linearized system model well represents dynamic modal structure in the longitudinal plane, whereas the dynamic modes in the lateral plane are not well captured by the linearized model due to a coupling between flight states (roll and yaw rate with sideslip speed) and a coupling between planes of motion (lateral disturbances excite longitudinal flight states).