Colibri: Hovering Flight of a Robotic Hummingbird

This paper explores the design, development and testing of a tailless, two-winged robotic hummingbird, named COLIBRI. The current version of our robot has a total mass of around 22 gr, a wingspan of 21cm and a flapping frequency of around 20Hz. The primary objective is to enhance its flight autonomy and stability. The control system incorporates two attitude reconstruction algorithms: a Complementary filter and a full state dynamic observer implemented as a Kalman filter. Both of them were designed to filter out the noise caused by the rapid flapping of the wings, ensuring accurate and reliable attitude estimation. They are implemented on a newly developed control board with enhanced performance and reduced weight. Experimental results demonstrate successful attitude stabilization and improve station keeping, despite significant flapping noise. Notably, the gear-based prototype achieved a maximum flight time of 4 minutes and 45 seconds, highlighting the effectiveness of the design improvements in extending flight duration.