The stealthy little drones that fly like insects
When Storm Ciara crossed the UK in February, Alex Caccia was strolling on Oxford’s Port Meadow to watch birds flying through the air.
He marveled at their indifference to the strong winds: “While airliners were rooted in time, birds couldn’t care less!”
It was not just a passing thought for Mr Caccia, who is the general manager of Animal Dynamics, a technological start-up that applies lessons from wildlife to drone design.
Formed in 2015 to pursue science known as biomechanics, his company already has two drones to show for an intimate study of the life of birds and insects.
One takes inspiration from a dragonfly and has attracted funding from the military. Its four wings make it constant strong winds that would defeat the existing miniature spy drones.
Known as Skeeter, the secret project solved the challenge of using wing wings to power a drone. While the wings are more efficient than a propeller and allow a dragonfly to hover in the face of strong gusts, they are almost impossible for human engineers to emulate.
“Making devices with flapping wings is very, very difficult,” says Caccia. Helicopters move by changing the pitch of the rotor blades to go back and forth or to hover. For smaller objects, hovering is a great challenge.
“A dragonfly is a fantastic flyer,” says Alex Caccia, “It’s crazy how beautiful they are, nothing is left to chance in that design. It has very sophisticated flight control.”
The dragonfly has 300 million years of evolution on its side. Animal Dynamics spent four years writing software that manages the hand-launched drone like an insect and allows it to hover in gusts of over 20 knots (23 mph or 37 km / h). From 22 to 27 knots it is classified as a “strong breeze”.
This software gives Skeeter a degree of autonomy and guides him through the obstacles towards his goal.
And it fulfills the Ministry of Defense’s desire for a wind-resistant miniature reconnaissance drone to allow soldiers to spy on hidden threats.
Skeeter will transport a camera and communication links to the skies and it should be inexpensive enough for operators to lose some without affecting the defense budget.
It is currently around eight inches long, but production versions are expected to be smaller. Compressing a lot of aerodynamic and navigational wisdom into a small package is a prerogative of nature, but it has been a great challenge for Animal Dynamics. “We started small to learn difficult lessons” as Alex Caccia states.
The 70-member team of Animal Dynamics relied on electronics from the smartphone industry to reduce their knowledge in Skeeter’s frame. Insights into robotics, biology and software all play a role in design, but cell phones have been an advantage for all mini-drone manufacturers.
Guido de Croon, associate professor at Delft University of Technology, recognizes the pioneers of the biomechanics of debt to smartphones. His team built a series of swing wing drones that are based on mass-produced digital components. “I am very happy with the mobile phone industry,” he says.
Under the DelFly family name, Mr de Croon’s creation weighs less than 50 g and is inspired by the movement of the wings of fruit flies. The four wings of DelFly are made of an ultralight transparent foil powered by a light and economic motor, which makes it fly for 6-9 minutes.
The wings may seem delicate, but they can touch a surface or even fly into an obstacle and DelFly will straighten up like an insect hitting a window. For most existing drones with fast-rotating propellers, such contact would be disastrous.
Smartphone camera lenses return vision to AI software, and Mr de Croon is developing algorithms that mimic an insect’s avoidance senses.
The goal of the DelFly team is to obtain an autonomous flight indoors, useful for roles such as monitoring crops within large greenhouses. Mr. de Croon believes that one day bio-mechanics could customize a drone for any purpose. “Every business has its ideal drone.”
At Animal Dynamics the stork, Skeeter’s much older and more public older sister, was inspired by the similarities between light paragliding wings and large birds. The stork is built to withstand blows and suffer the attentions of clumsy operators.
Built around a tubular metal frame that is easy to repair, it uses an electric motor that pushes a propeller facing backwards and has a folding sunshade for a wing.
Controlled remotely via GPS signals Stork’s brain consists of a black box that launches two small mushrooms which are antennas for the navigation system.
The current version has a load compartment the size of a shoebox, but a larger model could be launched in flocks to distribute food or medical supplies on inhospitable land in Africa or Latin America. The nylon paraglider folds into a bag and lifts up as the stork’s engine moves over any vaguely flat surface.
The machine lands almost vertically, so it can reach almost any point. Remote operation via GPS allows you to fly back to a central point once the load compartment is opened and emptied.
With its wheelchair tires and almost unbreakable chassis, Stork is a utility car. The designers call him a flying mule and this pushes Alex Caccia to perform his party piece, grabbing a stork resting on a work surface and throwing it on the floor where it is intact and not electronically disturbed.
Pharmaceutical giant Pfizer is working with Animal Dynamics to expand Stork’s potential in distributing medicines. Parts can be shipped and assembled locally by Ghanaian operators, where plans for managing UAVs for medical care are at an advanced stage.
As an alternative to 4x4s or motorcycles, Stork’s marriage of easy-to-master technology and robust design stands out in a world where the design of delivery drones has been distracted by efforts to fly parcels to urban consumers.
Bio-mechanics has a contrasting approach with that of most drone designers courtesy of dragonflies, storks, fruit flies and, of course, mules.