Friday, May 18, 2018

This autonomous glider could one day roam the oceans in packs

The work takes inspiration from the flight of the albatross to conceive an autonomous flying robot able to extract its energy from the winds of the ocean.
The ultimate motivation is that if energy is extracted from winds there is no need for refueling, so a robotic albatross could survey and study the oceans for weeks or months at a time, traveling tens of thousands of kilometers in a single mission.

From Silicon Republic by Colm Gorey

In an effort to better monitor the world’s oceans, a team from MIT has built a super-efficient glider, similar in design to an albatross.

The vastness of the world’s oceans makes it incredibly difficult for anyone to effectively monitor a large body of water, and while satellites have certainly helped, we have yet to find an effective Earth-based solution.

But now, a team from MIT has unveiled its latest creation based on the gliding power of the common seabird known as the albatross.

Engineers at MIT have developed a new model to simulate dynamic soaring, and have used it to identify the optimal flight pattern that an albatross should take in order to harvest the most wind and energy.
They found that as an albatross banks or turns, it should do so in shallow arcs, keeping almost to a straight, forward trajectory.
The first aspect of the research, the “model reduction step”, consists in deconstructing the physics of the albatross’ flight (called “dynamic soaring” in the field) in order to extract fundamental and general laws. 
-see article on dynamic soaring-
This step, which involves physical and mathematical analysis, flight dynamics, aerodynamics, geophysical fluid dynamics, and trajectory optimization, aims at identifying which aspects of the problem matter and which don’t, in order to generate a simple model of predictive power.
Model reduction is important when designing innovative systems, because often the design space is not well understood and very large; it is also helpful in numerous flavors of machine learning.

The autonomous glider is capable of skimming along the water’s surface in a glide similar to an albatross and is also capable of riding the waves like a sailboat.

The second aspect of my research, the “design and demonstration step” is about adapting the lessons learnt from the model reduction step in order to imagine and demonstrate a robot that combines the solutions found by biological systems with the capabilities of man-made systems.
More precisely, I propose a general framework for a bioinspired robot, characterize the design space and provide the underlying science and engineering for further developments.
I then demonstrate the most innovative and critical aspects of the system with a prototype.
This involves the design, fabrication/implementation and test of mechanical systems (the robot and test environment), electrical systems (sensors, actuators and communication), the embedded software (estimation and control algorithms), and their integration.
-Photo: Gabriel Bousquet-

‘The oceans remain vastly under monitored’

When dropped into a region of high wind, it is designed to stay aloft, and when the winds are calmer can become a sea-faring vessel.

Borrowing from both nautical and biological designs, the craft can cover a determined distance using one-third as much wind as an albatross, while travelling 10 times faster than a typical sailboat can as it weighs just under 3kg.

“The oceans remain vastly under monitored,” said Gabriel Bousquet who led the design of the robot as part of his graduate thesis.

“In particular, it’s very important to understand the Southern Ocean and how it is interacting with climate change. But it’s very hard to get there. We can now use the energy from the environment in an efficient way to do this long-distance travel, with a system that remains small-scale.”

 An albatross glider skims the Charles River.

Roaming in packs

The design came about last year after Bousquet and a number of other researchers looked into the dynamics of albatross flight to better understand how the bird could travel huge distances without exerting enormous amounts of energy.

The team found that the physics of the bird’s flight is very similar to that of sailboat travel as they both transfer momentum in order to keep moving.

In terms of speed, the craft should only need relatively calm winds of about five knots to zip across waters at a velocity of about 20 knots, equal to around 37kph.

Once the design was agreed upon, it was then a matter of adding the hardware which includes GPS, inertial measurement sensors, auto-pilot instrumentation and ultrasound to track the height of the glider above the water.

The team’s goal is to one day have a design which will allow for packs of these speedy skimmers to be deployed to cover huge areas of an ocean.

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