Unmanned cargo helicopters have proved their worth in Afghanistan, resupplying remote forward bases and taking convoys off dangerous roads. But the U.S. Army wants to take the next step, beyond carefully planned missions to autonomous operations, including obstacle avoidance and dynamic replanning.
Advanced capabilities are being developed byusing an unmanned Kaman K-Max external-lift helicopter as the testbed for the Army Aviation Applied Technology Directorate's Autonomous Technologies for Unmanned Air Systems (ATUAS) demonstration program. The initial demo, in April 2012, involved a ground beacon that enables loads to be delivered to within 3 meters (10 ft.) of a drop point.
The beacon was deployed to Afghanistan, where two K-Max unmanned helicopters were being used to resupply remote U.S.forward operating bases until operations were suspended in early June after one of the aircraft crashed.
The crash has not affected the ATUAS program, and in July Lockheed Martin conducted the second series of demonstrations at Fort Pickett, Va. These included passing high-definition video over high-bandwidth satellite communications to provide improved situational awareness for the operator.
“We swapped out the low-resolution EO/IR [electro-optical/infrared sensor] and put on a high-definition EO/IR, but that needed a much higher- bandwidth signal,” says Jon McMillen, business development manager for K-Max. “We wanted to do beyond line-of-sight, and still wanted to use satcom. So we integrated a high-bandwidth, Ku-band satcom dish under the rotors, and created a waveform to pipe the high-def video through the rotors,” he says.
McMillen says real-time video via satcom through the rotors is an “industry first.” To avoid blockage by the rotating blades, the waveform allows the signal “to shoot between rotor cycles, to go between the blades,” he says. Real-time video via satcom allows the remote operator to use a gimbaled EO/IR sensor—a Wescam MX-10 was used for the demo—to get a downward view from the helicopter and look around the drop zone, he says, reducing the need for personnel on site.
The latest demo also includes dynamic mission replanning. “In flight, we uploaded a no-fly zone direct to the air vehicle. The aircraft sensed the obstacle directly ahead, and automatically replanned around it,” McMillen says. The no-fly zone could represent a threat or airspace to be avoided. Replanning was performed on the aircraft, with the revised route displayed in the control station to alert the operator and provide the option to intervene.
Also demonstrated was obstacle avoidance and landing-zone selection using a three-dimensional laser radar. The K-Max used a Fairchild Controls Hellas lidar to autonomously check the landing zone slope, detect obstacles and select a safe area to drop the cargo.
The ATUAS demonstration is focused on long-line delivery of external loads—both single and multiple drops per flight—the method used by the K-Max to deliver cargo in Afghanistan. “We did both static and dynamic obstacle-detection,” says McMillen. “There was an SUV in the middle of the drop zone. The system tracked the vehicle, selected a safe area nearby and delivered the load.”
A final demonstration is planned for November. This operational utility assessment will include multi-vehicle control from the K-Max ground station, representing a team of cargo UAS. The demo will also include autonomous retrograde capability—bringing cargo back. This has been accomplished manually in Afghanistan with Marine Corps personnel making “hot hook-ups” to the hovering helicopter.
In the November demo, McMillen says, the unmanned helicopter will fly in, identify the load, autonomously attach its hook and fly away. “We are looking at a device on the load to identify it, and a couple of different hook technologies,” he says. This is an extension of the beacon, which allows the long-line load to be placed precisely, says McMillen, adding that automated damping of the long line on the unmanned K-Max already provides cargo-hook stability that is better than for the piloted aircraft.