Drones

Fixed-wing drone learns to land like a bird

The University of Bristol has created a UAV that is able to tilt up its wings to create more drag for landing, while morphing a section of those wings to provide just enough lifting force to maintain stable flight control and land like a bird
The University of Bristol has created a UAV that is able to tilt up its wings to create more drag for landing, while morphing a section of those wings to provide just enough lifting force to maintain stable flight control and land like a bird
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The University of Bristol has created a UAV that is able to tilt up its wings to create more drag for landing, while morphing a section of those wings to provide just enough lifting force to maintain stable flight control and land like a bird
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The University of Bristol has created a UAV that is able to tilt up its wings to create more drag for landing, while morphing a section of those wings to provide just enough lifting force to maintain stable flight control and land like a bird
The UAV has been trialed at altitude to prove the current methods and the team is in the throes of developing the system to the point that it can perform on-going and repeatable ground landings
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The UAV has been trialed at altitude to prove the current methods and the team is in the throes of developing the system to the point that it can perform on-going and repeatable ground landings
A combination of a morphing wing UAV and machine learning can be combined to perform a bird-style perched landing on the ground
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A combination of a morphing wing UAV and machine learning can be combined to perform a bird-style perched landing on the ground

We've all seen how birds touch down on a ledge. They swoop in, tilt up, and then open their wings wide at the last moment, flaring out like a parachutist to drop at almost zero speed onto the desired spot. It all seems very natural and easy for a bird. But for any sort of aircraft, especially a fixed-wing one, such a feat would be exceptionally difficult to say the least. Nevertheless, researchers at the University of Bristol claim to have achieved this with an unmanned aerial vehicle that has learned to land like a perching bird with the help of some clever algorithms and morphing wings.

Ordinarily, when a fixed-wing plane flies, air resistance against its body in flight is a measure of its drag coefficient. An aircraft is designed to minimize its drag coefficient so that it stays in the air, but when it needs to slow to land, it must increase that drag by tilting back so that its wings present more surface area to the oncoming air. Tilting back too far at too slow a speed, however, and drag can quickly exceed lift, leading the plane to stall, lose control, and possibly crash.

The University of Bristol UAV, on the other hand, is able to tilt up its wings to create more drag for landing, while morphing a section of those wings to provide just enough lifting force to maintain stable flight control. To control these complex wing structures, University of Bristol researchers (in conjunction with BMT Defence Services) employed machine learning algorithms to develop a flight controller inspired by birds.

The UAV has been trialed at altitude to prove the current methods and the team is in the throes of developing the system to the point that it can perform on-going and repeatable ground landings
The UAV has been trialed at altitude to prove the current methods and the team is in the throes of developing the system to the point that it can perform on-going and repeatable ground landings

In this way, the researchers have shown how the combination of a morphing wing UAV and machine learning can be combined to perform a bird-style perched landing on the ground. The UAV has also been trialed at altitude to prove the current methods and the team is in the throes of developing the system to the point that it can perform on-going and repeatable ground landings.

It's not the first UAV to employ morphing wing technology, UC San Diego demonstrated a version of their own quite a while ago, and NASA has been testing variable-geometry wings as part of its Adaptive Compliant Trailing Edge (ACTE) project. But the University of Bristol UAV is the first to effectively use such technology to bring in a UAV to land like a bird.

"The application of these new machine learning methods to nonlinear flight dynamics and control will allow us to create highly maneuverable and agile unmanned vehicles," said Dr Tom Richardson, Senior Lecturer in Flight Mechanics in the Department of Aerospace Engineering at the University of Bristol. "I am really excited about the potential safety and operational performance benefits that these new methods offer."

Delivered as part of an 18-month project for the Defence Science and Technology Laboratory's Autonomous Systems Underpinning Research program, the research will help add to the development, production, deployment and operational use of intelligent unmanned systems by UK Armed Forces.

The short video below shows the UAV in action.

Source: University of Bristol

Learning to perch a UAV on the ground using deep reinforcement learning

5 comments
Bob
The other day I was watching a hawk hunt mice in the field behind my house. Usually they are gliding at around 100 feet and dive down when they see a mouse. This hawk was gliding only about five to six feet above the ground. When he saw a mouse he did a 180 degree pivot in the air and dropped straight down on his target. What was so interesting was his maneuver. He did a full stop of forward motion and a 180 degree turn in less than a couple feet and immediately dove on the target from just six feet above it. I'm guessing that his forward glide speed had to be 15-20 mph. I was wondering what kind of G force such a sudden maneuver would require? I watched him do this about three times before he successfully snagged a fat mouse and flew over to perch on a fence post for his lunch.
PAV
Next step extend claws and grasp, fold in wings, then poop.
alan c
What's the advantage? UAV's with vectored thrust can already do this. A skilled RC aerobatic flyer with a fixed wing aerobatic model can fly a fully stalled, fully controlled landing; that would be a good starting point to model.
RoelCoert
As a hanglider pilot, you ar thought just the same manoeuver as depicted by the RC aircraft: Approach, bleed of speed and when about 1 m above the ground push out the speed bar to stall and kill the forward motion. The push out should be done rapidly so that the wings stalls and doesn't generate lift (gain altitude). It takes a few lessons to master (if you master :-))
habakak
Why does the model have a cockpit if it's intended for UAVs?
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