Fractional calculus helps control systems hit their mark

Fractional calculus helps control systems hit their mark

If you’ve ever searched for ways to curb your car’s gas-guzzling appetite, you’ve probably heard that running on cruise control can help reduce your trips to the pump. How? Cars, it turns out, are much better than people at following what control systems experts call a setpoint—in this case, a set speed across varying terrain. Calling upon a branch of mathematics known as fractional calculus, a team of researchers has developed a new setpoint-tracking strategy that can improve the response time and stability of automated systems—and not just those found in your car.

One popular method for tracking setpoints is to use what’s known as a setpoint filter. A setpoint filter helps solve the problem of under- or overshooting a far-away target. Blast furnaces, for example, have to go from to precisely thirteen hundred degrees to infuse iron with carbon to make steel. Some temperature controllers may overshoot as they quickly try to reach that temperature. Adding a setpoint filter smooths the path to make sure the furnace reaches the target temperature without going over. The problem, of course, is that it takes longer to get there. That’s where fractional calculus comes in.

Compared with classical (or integer-order) calculus, which forms the mathematical basis of most , fractional calculus is better equipped to handle the time-dependent effects observed in real-world processes. These include the memory-like behavior of electrical circuits and chemical reactions in batteries. By recasting the design of a setpoint filter as a problem, researchers created a filter that could not only suppress overshooting but also minimize the of a virtual controller

Fractional calculus helps control systems hit their mark

A side-by-side comparison showed that their fractional filter outperformed an integer-order filter, tracking the complex path of a given setpoint more closely.

One drawback of this fractional design is that it’s difficult to incorporate into existing automated systems, unlike integer-order filters, which are generally plug-and-play. But as the world of automation becomes increasingly complex, fractional may ultimately set the new standard for controlling everything from robotics and self-driving cars to medical devices.

Read more at: http://phys.org/news/2016-12-fractional-calculus.html#jCp

Read more at: http://phys.org/news/2016-12-fractional-calculus.html#jCp

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Preparing for air traffic control via satellite

ESA recently completed its first flight trials using satellites to help bring Europe closer to its goal of modernising air traffic control.

The trials are part of the public–private partnership between ESA and UK satellite operator Inmarsat to deliver high-capacity secure digital data links via satellite for air–ground communications for cockpit crews over European airspace under ESA’s Iris Precursor programme.

By 2019, Iris Precursor will provide air–ground communications for initial ‘4D’ flight path control, pinpointing an aircraft in four dimensions: latitude, longitude, altitude and time. This will enable precise tracking of flights and more efficient management of traffic.

An aircraft from the Netherlands Aerospace Centre carried a prototype Iris terminal connected to Inmarsat’s next-generation SwiftBroadband-Safety satellite service as it took off from Amsterdam.

During four flights to different destinations in Europe, the connection between the aircraft and ground networks was tested extensively and air traffic control messages were exchanged. The connection was maintained even when the aircraft switched satellite beams.

Captain Mary McMillan, Inmarsat’s Vice President of Aviation Safety and Operational Services, said: “As air traffic volume continues to increase, the digitisation of the cockpit is one of the ways to alleviate current congestion on traditional radio frequencies and optimise European airspace.

“Using the power and security of satellite connectivity through Iris clearly changes the game in comparison to the ground technology in use today.”

These flight trials complement a separate test flight by Airbus with Inmarsat and other partners in March this year, providing initial 4D flight path control and data link communication exchanges between the pilot and air traffic control.

At the end of next year, Inmarsat plans a second phase of flight trials to validate the Iris technology.

The next step is to use Iris on commercial flights in a real air traffic management environment.

“ESA’s Iris programme is forging ahead as part of Europe’s long-term goal to modernise air traffic control. A stepped approach and good collaboration between public and private partners is bringing excellent results,” commented Magali Vaissiere, Director of Telecommunications and Integrated Applications at ESA.

Iris is part ESA’s collaboration with the Single European Sky effort of the European Commission, Eurocontrol, airport operators, air navigation providers and aerospace companies in a push to boost efficiency, capacity and performance of air traffic management worldwide.