Abstract:
This paper describes the development of a biomimetic robotic hummingbird that utilizes biologically inspired wing kinematic modulation strategies for active stability and control. By tilting the flapping planes, varying the relative wing flapping amplitude, and shifting the mean position of the flapping stroke, the robotic hummingbird is able to modulate the magnitude, direction, and location of the lift vector of each of the wings in the same way that hummingbirds do to maneuver and stabilize themselves. In addition to the control strategies, biologically inspired, flexible, aeroelastically tailored wings were developed for use on the vehicle. Flight tests were conducted in which the vehicle was flown in a controlled hover using combinations of control techniques to quantify the effectiveness of each in stabilizing the vehicle. In the present study, emphasis was placed on pitch control, where two different control strategies were investigated, which were (1) pure tilting of the stroke plane, and (2) stroke mean shifting. Based on the flight experiments, a combination of 90% mean shifting and 10% stroke tilting proved to be significantly more effective than pure stroke plane tilting with almost 40% decrease in drift and attitude oscillations. This is the first ever study where the exact kinematic control strategies used by real hummingbirds and two-winged insects are implemented on a robotic flyer and investigated through free-flight testing.