Sikorsky has dialed up the autonomous flight control system on an experimental UH-60A Black Hawk to where a pilot can “set it and forget it” during long surveillance missions, another step toward flying the aircraft remotely from the cabin or from the ground without pilots on board.
To date, Sikorsky has put 54.5 flight hours on its optionally piloted vehicle (OPV) flight control system, which is designed as a kit that replaces all legacy mechanical controls in existing aircraft with its MATRIX autonomous fly-by-wire controls. It has also run about 30 hours on the ground in the UH-60A, one of the oldest Black Hawks in the Army’s inventory, according to chief test pilot Mark Ward.
During the first of MATRIX in a Black Hawk in May, Sikorsky focused on the direct mode control scheme, which means the fly-by-wire controls should fly and respond to pilot input like a conventional UH-60 Black Hawk, Ward said. Technically, the mode is “direct stick-to-head with stability augmentation in the loop.”
“Direct mode is supposed to be, more-or-less the service mode or an emergency mode, but we found the aircraft behaved quite well throughout all the speed regimes in that mode,” he said.
Sikorsky briefly paused the flight test program to “fine tune” some of the pilot control augmentation modes, “so that when we go to autonomy we’re going to have a very mature system that goes from full-spectrum of pilot 100 percent in the loop, to autonomy 100 percent in the loop and everywhere in between,” he said.
Test pilots have since ratcheted up computer control of the aircraft and expanded the flight envelope out to 150 knots indicated airspeed. Most interestingly, the test team is beginning to increase the level of flight control augmentation beginning with “direct mode.”
In “rate command attitude hold” mode, the fly-by-wire system takes over more control of the aircraft, Ward said. That mode was tested through low-speed hover maneuvers out to 150 knots.
“When you put a control input, you’re controlling a rate or an attitude change and when you release the control, you’re capturing that attitude,” he said.
From there, test pilots increased autonomous control of the aircraft to the full authority control scheme, or FACS, in which “rather than commanding a rate, you’re actually commanding a parameter, such as airspeed or altitude or heading using the control stick,” Ward said.
“To change from one mode to the next is simply a button push away to go from direct to rate command, up to FACS and back down,” he said. “Think of full authority as being an ultra-stable ISR platform that is going to be holding flight parameters for very long periods of time,” he said. “You kind of want to set it and forget it. You’re not turning knobs on a flight director. You are actually flying the aircraft with the control stick.”
“Rate command is when you kind of want to . . . throw it around a little bit, you want to do some low-and-slow or low-and-fast maneuvering where you’re going from stop to stop to complete a mission.”
Sikorsky uses the phrase “optimally piloted vehicle” as well as “optionally piloted vehicle” when discussing OPV and MATRIX because the ultimate goal is to develop a system that can act as an autonomous co-pilot quietly but constantly aiding human operators during specific missions.
The OPV kit is tailored to the UH-60, but is retrofittable onto the Army’s entire helicopter fleet and Sikorsky’s commercial S-92 and S-97 rotorcraft, according to Igor Cherepinsky, the company’s director of autonomy. Sometime in 2020, Sikorsky will demonstrate that the system can be remotely piloted from both inside and outside the aircraft, he said.
“We will show the world this system is capable of being operated from the ground,” he said. Sikorsky continues to demonstrate MATRIX on a modified S-76B called the Sikorsky Autonomy Research Aircraft (SARA). The aircraft, which has been in test since 2013, has more than 300 hours of autonomous flight. The company announced in March that its S-92 helicopter fleet update will include the introduction of phase one MATRIX technology, which will allow for autonomous landing.
The U.S. Army has plans to outfit a UH-60M with the system but is about six months behind Sikorsky’s OPV test program.
“Our vision is, obviously, not to replace the pilots, but to augment the pilots,” Cherepinsky said. “Once we field the technology, we never want to see another controlled flight into terrain or degraded visual environment issue accident ever happen with any of our aircraft.”