Flight Dynamics Identification, Maneuverability, and Gust Tolerance of a Robotic Hummingbird in Hover

Abstract

This paper discusses an endeavor to experimentally identify the flight dynamics of the AVFL Hummingbird, and quantify its maneuverability and gust tolerance using a control theoretic framework. The AVFL hummingbird is a 62gram, truly biomimetic robotic hummingbird developed to understand and characterize hummingbird flight. It has a pair of biologically inspired, aeroelastically tailored wings flapping at 20Hz, and is fully hover capable. Additionally, like its biological counterpart, it utilizes wing kinematic modulation techniques for control and stability. The vehicle states were measured during targeted flight tests from which a linearized, state-space model was derived. The model contained damping aerodynamic coefficients, decoupled longitudinal, lateral and directional dynamics, as well as large control coefficients. The control theoretic framework, which quantifies the maximum controllable states of the system under unit inputs, was utilized to calculate the maximum gusts tolerable by the control system. The results showed exceptional gust tolerant capabilities. The maximum gusts tolerable were (1) longitudinal gust: 21.2 ft/s (6.4 m/s); (2) lateral gust: 17.7 ft/s (5.4 m/s); (3) lateral rotational gust: 149.8 rad/s; and (4) longitudinal rotational gust: 20.5 rad/s. These are much greater than comparable rotary-wing based systems. This study represents the first time the maneuverability and gust tolerance of a hummingbird-like system has been experimentally characterized, and has shown quantitatively the exceptional flight capabilities offered by biomimetic design and control.