It’s all in the math for Athena’s UAV control systems

  • 30-Jun-2008 07:01 EDT
Athena Shadow TUAS.jpg

Both the German-built Luna UAV and the Shadow tactical unmanned air system (shown) have autonomous navigation and control systems from Athena Technologies.

A variety of manufacturers have successfully shown how small, tactical, relatively low-cost UAVs can provide soldiers and marines on the ground with timely data on enemy positions. One of the keys to such programs is not the electro-optic/IR sensors through which data is collected, but the autonomous control systems that make such systems operable.

Engineers working for companies that develop autonomous control systems for UAVs tell stories about potential customers who think that creating an autonomous command and control system for a small UAV is akin to flying a hobbyist’s radio-controlled aircraft and can be accomplished in a weekend. That misconception does not last long, though.

“Unmanned vehicles are limited in size, power, and the amount of weight they can carry,” said Dave Vos, founder, Chief Technology Officer, and CEO of Warrenton, VA-based Athena Technologies. “If you look at the way many of the manned aviation autopilots in general aviation were developed, you’ll see a lot of trial and error. You can do that with unmanned systems, but it is risky and expensive.

“The challenge is to push the button for the first time and have it work. If you can do that, you can save a tremendous amount of time and money in getting a vehicle up and flying in the marketplace.”

Athena’s main program is the U.S Army’s Shadow 200 UAV built by IAI. Athena has supplied “hundreds” of systems to the Shadow program since 2001.

“Since then we’ve essentially shrunk 20 lb of stuff down to a 4-lb cube while improving the accuracy of the control system and navigation, which impacts every phase of flight from launch to mission,” said Vos.

“The control theory is straight-up mathematics,” he said. “Without knowing exactly how the airplane will behave, we use non-linear control design theory and modeling so all you essentially do is push the button on the math tool set. That is followed by engineering qualification.

“Then you’re ready [to fly]. That cycle is extremely fast and robust. The military loves it because they get to test it more and it behaves the way they want it to very quickly,” said Vos.

The market to develop UAV command and control is extremely competitive, particularly on the smaller Class I end.

“Military customers have a mission they need to perform, and they want to do it extremely reliably and at low cost,” said Vos. “That’s why this market is so unbelievably competitive. In competition against the incumbents like Honeywell and Rockwell Collins, companies like Athena have been required to show up with performance and prices that they cannot match.”

Athena was founded in 1998, and grew 1400% from 2000 to 2005, according to Vos. It employs 75 people. “We focused on winning major programs, not serving onesy-twosy activity,” said Vos.

Though, admittedly, some of that one-off work could be potentially lucrative. Athena’s research and development into controlling and autonomously landing a damaged UAV is one such program.

“How attritable is an unmanned airplane?” asked Vos. “There are a lot of issues. If it goes down into enemy territory, the current protocol is to send soldiers out to retrieve it. One of the key pieces with damage tolerance is to maintain flight control, but even if you have to put it down you have a better chance of getting it into friendly territory.”

Last year, Athena and DARPA successfully demonstrated damage-tolerant flight control and autonomous landing capabilities on a subscale F/A-18 UAV. “The program lives on top of the control and navigation function,” said Vos.

The objective of the test was to prove that adaptive flight controls could regain baseline aircraft performance after the aircraft had sustained simulated battle damage and then safely land the aircraft autonomously with only the onboard inertial navigation system (INS)/GPS functionality of an Athena system for navigation.

The subscale F/A-18 UAV was powered by a turbojet engine and sustained simulated wing damage and the in-flight ejection of an aileron. Athena’s damage-tolerant controls detected the damage in flight and adapted to the new air vehicle configuration for the effects of the lost aileron, recovering the baseline vehicle performance. Using only Athena’s INS/GPS autonomous landing system, the vehicle landed within a few feet of the target touch down point on the airfield runway.

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