Comparative dynamic flight stability of insect-inspired flapping-wing micro air vehicles in hover: Longitudinal and lateral motions

Abstract

In this paper, we compare the characteristics of hovering stability for two insect-inspired flapping-wing micro air vehicles (FW-MAVs) with different strategies to generate control moments for the longitudinal and lateral attitude controls. The two robots were named according to their control mechanisms, i.e., the Stroke-Plane-Change (SPC), and the Trailing-Edge-Change (TEC). The forces and moments produced by flapping wings were computed by the computational fluid dynamics (CFD) method. The longitudinal and lateral flight characteristics were identified as one fast subsidence mode, one slow subsidence mode, and one divergence oscillation mode. The results revealed that the fast and slow subsidence modes in the longitudinal and lateral motions of the SPC were stabilized faster than those of the TEC, while both of the lateral and longitudinal divergence modes of the SPC were more unstable than those of the TEC. Moreover, the effect of the longitudinal and lateral derivatives on the system poles of the SPC were investigated. The results showed that the major source of instability in the longitudinal motion was the pitching derivative with respect to the horizontal speed, Mu+. Meanwhile, that in the lateral motion was the rolling derivative with respect to the horizontal side speed, Lv+. Overall, the time response of the SPC, when the body was disturbed by an external force, was relatively faster than that of the TEC. Therefore, using the SPC mechanism can give the FW-MAV more agility to operate in highly cluttered spaces with obstacles.