DelFly

DelFly Explorer, a 20 gram flapping wing MAV with stereo camera and onboard image processing to avoid obstacles.

DelFly Micro, a 3.07 gram camera equipped flapping wing MAV.

The DelFly is a fully controllable camera-equipped flapping wing Micro Air Vehicle or Ornithopter developed at the Micro Air Vehicle Lab of the Delft University of Technology.

The DelFly project^[1] focuses on fully functioning systems and follows a top-down approach toward ever smaller and more autonomous flapping wing MAVs.

The DelFly Micro with its 10 cm wing span and 3.07 grams is still the smallest untethered, free flying, fully controllable (thrust, elevator, rudder) flapping wing MAV equipped with a camera and video transmitter carrying its own energy source.^[2]

The 28 centimeter 16 gram DelFly II performed ground-breaking work in the area of autonomous flight, mainly using off-board processing. ^{[3] [4] [5]}

The DelFly Explorer is the latest development. It measures 28 centimeter while weighing 20 grams. It is equipped with a miniature stereo vision system enabling fully autonomous flight in unknown environments.

History

The DelFly project started in 2005 as a Design Synthesis Exercise for a group of Bachelor of Science students at the Faculty of Aerospace Engineering of the TU Delft. The result of this exercise was the DelFly I, a 50 cm wingspan, 21 grams flapping wing MAV equipped with a camera. The DelFly I was able to fly but could not hover, and there was considerable motion perturbing the camera images.

In 2007, the DelFly II was created: a 28 cm wing span 16 gram flapping wing MAV equipped with onboard camera. This version was not only smaller, but it had a much broader flight envelope ranging from 7 m/s forward flight to hover and even backward flight at -1 m/s. The flight time of the DelFly II was around 15 minutes.

The DelFly II was followed in 2008 by the DelFly Micro, a 10 cm wing span, 3.07 gram flapping wing MAV, also equipped with camera.^[6] The DelFly Micro is fully steerable with 3 controls for the throttle, elevator and rudder. Given the limited onboard energy, the flight time of the DelFly Micro was around 2 to 3 minutes. The DelFly Micro featured in the Guinness book of records 2009 as the smallest airplane in the world equipped with a camera.

The DelFly participated in the 2005, 2007, 2008, 2010 and 2013 editions of the Micro Air Vehicle Competitions and was the first vehicle to demonstrate fully autonomous indoor flight.^[7]

The DelFly Explorer was created in 2013. It has a stereo vision system that allows autonomous obstacle avoidance even in unknown and unprepared environments.

Influence

DelFly has influenced Micro Air Vehicle developments and research since 2005. The Robobee, the TechJect Dragonfly UAV and FlyTech Dragonfly among many others refer to DelFly developments.

Design challenges

The design of autonomous, light-weight, less than 20 grams flapping wing MAVs poses challenges in various domains, including materials, electronics, control, aerodynamics, computer vision and artificial intelligence All these domains feed into each other. For example, studies on the design and aerodynamics of the wings have enhanced the efficiency of flight and the amount of generated lift. This allows for a larger payload to be taken on board, such as more onboard sensors and processing. In turn, such onboard processing can be used to perform automatic maneuvers in a wind tunnel, helping to create better models the DelFly and its low Reynolds aerodynamics.

Applications

Flapping wing MAVs have a natural appearance and are inherently safe by means of their low weight and low speeds of the wings. This makes them particularly suitable for indoor flight, also in the presence of humans. Obviously, flapping wing MAVs can be used as (augmented reality) toys, but other possible applications include inspection of indoor industrial structures or video streaming of the crowd during concerts.

References