Taking a close look at wings in nature

Article of 29 March 2018 

Technik in 60 Sekunden - Fliegen

The dream of flying is one of the oldest known to humankind. In this respect, we have always looked at the animal world with fascination – a world that shows how it is done in all sorts of ways. In the Bionic Learning Network too, flying is always a recurring theme. In association with universities, institutes and development firms, Festo has, for years now, been developing research platforms whose basic technical principles are derived from nature.

First of all, our bionics experts took a close look at the fins on the manta ray. Although this creature lives in the water, its large pectoral fins beat up and down like wings when it swims. We transferred this principle to the Air_ray in 2007. Thanks to its lightweight construction, the uplift provided by helium and its beating-wing drive with Fin Ray Effect®, it moves in the air like its natural role model in the sea. A similar concept is also behind the AirPengiuns from 2009. Their flying technology is very close to the swimming technique of their biological models. The passively twisting wings allow both forward and reverse thrust to be generated.

From the water into the air

Building on this, in 2011 we unearthed the secret of bird flight and presented the SmartBird. The bionic technology platform, inspired by the herring gull, can start, fly and land by itself – without additional drive. Not only do its wings beat up and down, but they also twist in a specific manner. This is done by an active hinged-torsion drive, which, in conjunction with a complex control system, achieves previously unattained efficiency levels in flight.

BionicOpter: flying skills of the dragonfly

An even more complex kind of flying can be observed with the dragonfly. Its flying skills are unique: it can manoeuvre in all spatial directions, remain still in the air and sail without beating its wings at all. Due to its ability to move both pairs of wings independently of each other, it can brake and turn abruptly, accelerate rapidly and even fly backwards. Our bionics team technically implemented these highly complex properties in an ultra-lightweight flying object in 2013 in the form of the BionicOpter. It is the first time that a model has been able to master more flight conditions than a helicopter, motorised aircraft and glider put together. By controlling the flapping frequency and rotation of each wing, all four wings can thus be individually adjusted in terms of the direction and strength of thrust. In this way, the remotely controlled dragonfly can assume almost any position in any space.

eMotionButterflies: flying collectively

Festo perfected lightweight construction and miniaturisation in 2015 with the eMotionButterflies: each of the bionic butterflies weighs just 32 g. In order to replicate their natural role model as closely as possible, the eMotionButterflies feature highly integrated on-board electronics. They are able to activate their wings individually with precision and thereby perform fast movements. Ten cameras installed in the room record the butterflies using their infrared markers. The cameras transmit the position data to a central master computer which externally coordinates the butterflies.

BionicFlyingFox: whilst in flight, a master computer compares the target flight paths of the artificial flying fox with the actual ones. Using machine learning, it adjusts these with increasing efficiency.

BionicFlyingFox: semi-autonomous flying

The bionic engineers have developed this intelligent networking system further and will demonstrate the BionicFlyingFox, which even flies semi-autonomously, at the Hannover Messe 2018. This feature is possible due to the combination of on-board electronics and an external camera system. This allows the artificial bat with a wingspan of 2.28 m to fly through the skies. An elastic airtight membrane stretches from the tips of the fingers to the feet of the artificial bat. The specially developed membrane consists of a knitted elastane fabric and films welded together at selected points. Thanks to this honeycomb structure, the BionicFlyingFox can fly even if the bionic fabric sustains minor damage.

As different as the flying behaviour of creatures in nature may be, when transferring it to technology, the major challenges are always its lightweight construction and functional integration. With the BionicFlyingFox, on which all the articulation points of its highly stressed kinematics are on one plane to allow the entire wing to be folded together like scissors, Festo has now decrypted all types of flying found in the animal world. Yet nature provides many other unique solutions which will inspire the bionics team to find new technical solutions in the future.

If you want to witness the BionicFlyingFox during its flying show, visit Festo from 23 to 27 April 2018 at the Hannover Messe.