Practical Flapping Mechanisms for 20cm-span Micro Air Vehicles

[[abstract]]In the body of research relevant to high-performance flapping micro air vehicles (MAV), development of light-weight, compact and energy-efficient flapping mechanisms occupies a position of primacy due to its direct impact on the flight performance and mission capability. Realization of such versatile flapping mechanism with additional ability of producing thrust levels that fulfill requirements of cruising forward flight and vertical take-off and landing (VTOL) conditions demand extensive design validation and performance evaluation. This paper presents a concerted approach for mechanism development of a 20 cm span flapping MAV through an iterative design process and synergistic fabrication options involving electrical-discharge-wire-cutting (EDWC) and injection molding. Dynamic characterization of each mechanism is done through high speed photography, power take-off measurement, wind tunnel testing and proof-of-concept test flights. The research outcome represents best-in-class mechanism for a 20 cm span flapping MAV with desirable performance features of extra-large flapping stroke up to 100°, minimal transverse vibrations and almost no phase lag between the wings.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]US

Robust Linear Longitudinal Feedback Control of a Flapping Wing Micro Air Vehicle

This paper falls under the idea of introducing biomimetic miniature air vehicles in ambient assisted living and home health applications. The concepts of active disturbance rejection control and flatness based control are used in this paper for the trajectory tracking tasks in the flapping-wing miniature air vehicle (FWMAV) time-averaged model. The generalized proportional integral (GPI) observers are used to obtain accurate estimations of the flat output associated phase variables and of the time-varying disturbance signals. This information is used in the proposed feedback controller in (a) approximate, yet close, cancelations, as lumped unstructured time-varying terms, of the influence of the highly coupled nonlinearities and (b) the devising of proper linear output feedback control laws based on the approximate estimates of the string of phase variables associated with the flat outputs simultaneously provided by the disturbance observers. Numerical simulations are provided to illustrate the effectiveness of the proposed approach

Phasing of dragonfly wings can improve aerodynamic efficiency by removing swirl

Dragonflies are dramatic, successful aerial predators, notable for their flight agility and endurance. Further, they are highly capable of low-speed, hovering and even backwards flight. While insects have repeatedly modified or reduced one pair of wings, or mechanically coupled their fore and hind wings, dragonflies and damselflies have maintained their distinctive, independently controllable, four-winged form for over 300 Myr. Despite efforts at understanding the implications of flapping flight with two pairs of wings, previous studies have generally painted a rather disappointing picture: interaction between fore and hind wings reduces the lift compared with two pairs of wings operating in isolation. Here, we demonstrate with a mechanical model dragonfly that, despite presenting no advantage in terms of lift, flying with two pairs of wings can be highly effective at improving aerodynamic efficiency. This is achieved by recovering energy from the wake wasted as swirl in a manner analogous to coaxial contra-rotating helicopter rotors. With the appropriate fore–hind wing phasing, aerodynamic power requirements can be reduced up to 22 per cent compared with a single pair of wings, indicating one advantage of four-winged flying that may apply to both dragonflies and, in the future, biomimetic micro air vehicles