By J.C. Milliman, TEAM Public Affairs, Pax River

U.S. NAVAL AIR SYSTEMS COMMAND, Patuxent River, Md. – Seeking the breaking point where control system delays cause unmanned aerial vehicle (UAV) operators to lose control of their vehiclesaircraft, engineers here are flying – and test crashingPioneer and Predator UAVs by the hundreds in the Air Combat Environment Test and Evaluation Facilities Manned Flight Simulator.

The testing will aid in establishing latency standards, or what exactly the delays and breaking points are, in situations like landing or shipboard recovery, according to Air Force Capt. Barry Carlson, Pioneer Tactical Control System project officer for the testing.

With limited ground station and data-link processing speed competing for the operators to control their vehicles, especially during busy phases like landingtransmission of control and payload data, knowing the "breaking point" where operators lose control will also help designers, according to Carlson.

"We need to figure out the standard to be able to tell designers what the control station latency threshold is, so they can design within it and prioritize data transmission," Carlson said. "Unmanned air vehicle ground control stations have inherent latency starting from operator input through operator feedbackto the UAV and back before the operator sees a response. The latencies vary from UAV to UAV and from situation to situation and can pose a risk to the operation of the vehicleaircraft. Currently, there are no published standards for UAVs that identify appropriate latencies from operator input to feedback."

As an example, NAWCAD Test Lead Carlson Mark Easter explained that a manned aircraft, such as an F/A-18 Hornet, can flies with delays of less than a tenth of a second between a pilot moving the flight controls and perceiving the result. A UAV operator sitting on the groundthe ground in a TCS does not have the same physical sensations or visual cues and relies solely on electronic data transmitted back to maintain control.

"The UAV operator doesn’t experience the g-forcesphysical sensations we are accustomed to in flight," he said. "He has no direct sensory input to tell him what the vehicle is doing." "The UAV operator doesn’t get light in his seat when the vehicle dives," he said. "So he has no direct sensory input to tell him what the vehicle is doing."

To find where the "breaking point" is, the testers are focusing on the busiest phase of the UAV flight – the landing – and introducing delays in the data flow to test the effects on the vehicles controllabilitypilot’s ability to control the vehicle.

That can be challenging for the operator, according to Petty Officer 1st Class David R. Lampe, a Pioneer operator assigned to VC-6’s Patuxent River detachment and test participant. Even more so when delays are added.

"I make my input but it doesn’t respond, so I input more," he said. "Then it all catches up and I overcorrect the other way and it goes downhill from there."

Literally.

"We crash that thing hundreds of times," he added, referring to the test work in the simulator. "But you just reset the simulator and go flying again – no mishap boards, no paperwork. ! It’s a smarter approach to testing through by using the computer-enhanced system."

Finding the maximum latency for the $750,000 Pioneers and the $1.5 million Predators in the simulator still required the actual operators, though, according to Lampe.

"The programmers engineers tried flying it," Lampe said. "They couldn’t. They said ‘We need real operators.’ They had fun trying though."

Lampe conceded that the simulator and latency testing is not quite like flying the real thing.

There is a rule prohibiting operation of an actual UAV after simulation. "You can’t fly the real aircraft for 24 hours after flying the simulator," he explained. "I was driving home in my van after a test and had to pull over – ‘Whoa!’ I said, ‘Now I know why.’ Everything happened faster."

The latency testing is unique for several reasons, according to Dave Luna, MFS ACETEF simulation engineer and technical lead for the study.

"We’re using the (Pioneer’s) actual Tactical Control System hardware to drive the MFS visuals and UAV performance model simulations," Luna explained. "And, this is the first program to use the Quantum 3-D image generators – giving us high-resolution pictures at a much lower cost. The opportunity to use this new visualization system to solve a critical UAV design question makes this a win/win project.It’s a win/win project"

The test system included models of both UAVs’ flight characteristics developed by ACETEF’s 4.3 Research and Engineering department. Working on these models was an interesting diversion from high performance fighters for Jay Nichols, aerodynamics engineer assigned to the project.

"You have to think Cessna, not F-18," Nichols commented.

Previous image generators filled entire rooms and cost hundreds of thousands of dollars, according to Luna. The new image generators are the size of severalrunning on personal computers and cost a fraction of the old systems.

This kind of hardware "in-the-loop" testing, using actual UAV systems and operators, provides much more accurate datavery good results, Luna stated.

In addition to establishing latency standards for the two UAV’s, another purpose for the testing is to assess the potential of the hardware "in- the- loop" TCS simulations for future trainingtesting, demonstrations of new payload technologies, new vehicle integration and human/computer interface development, according to Carlson. And at $750,000 per vehicle (for a Pioneer), using the simulator is a much better way to find out than to risk crashing the real thing.

The testing finished Jan. 14 and data analysis is underway February.