Autonomy for umanned (and manned) rotorcraft has taken a big step forward with recent demonstrations of the ability of testbed helicopters to autonomously select safe landing zones. The development is key to enabling anyone on the ground to request an unmanned resupply flight or casualty evacuation without having to know anything about how the helicopter performs or what it needs to land safely.
You can read more about these demos in the latest issue of Aviation Week & Space Technology.
Aurora AACUS demo (Photos: ONR)
Two of the demos took place at Quantico, Virginia, under the Office of Naval Research's (ONR) Autonomous Aerial Cargo/Utility System (AACUS) research program. One was conducted by Aurora Flight Sciences using Boeing's H-6U Unmanned Little Bird (pictured above); the other by Lockheed Martin using an unmanned Kaman K-Max helicopter (below). Both were equipped with electro-optical/infrared and lidar sensors and autonomy processors that performed path and trajectory planning on board in real time.
Lockheed AACUS demo (Photos: ONR)
In each demo, a field operator with minimal training used a handheld tablet to request a resupply flight and indicate a landing location on a digital map. The request was set to a "main operating base" where the ground control system loaded a mission plan on to the helicopter. Once airborne the aircraft (with safety pilot on board) switched to autonomous mode and the AACUS package took over.
En route, AACUS navigated around no-fly zones that were loaded into the mission plan and also uplinked from the field operator to indicate pop-up threats to be avoided. On final approach, the helicopter contacted the operator and requested permission to land. Given approval, AACUS began using the lidar to assess the requested landing site for obstacles, slope and surface condition to determine if it was safe.
If the system decided the requested location was not safe, AACUS began looking for alternative landing zones that were, sending its recommendations to the field operator for display on the tablet. The operator picked one and the helicopter went ahead and executed an autonomous landing. The demos included various contingencies, including either the operator or the helicopter itself waving off a landing.
The February demos proved the basic AACUS concept is feasible. The next step is to expand the capability, mature the technology, increase the ability to detect and avoid small obstacles including power lines, test the system in different obscurants and precipitation, and demonstrate AACUS can operate in a GPS-denied environment. The next demo is planned for 2015.
Sikorsky, meanwhile, is making rapid progress on autonomy development under its company-funded Matrix Technology program. The Sikorsky Autonomous Research Aircraft (SARA), an S-76 modified with full-authority fly-by-wire flight controls, has been flying since July 2013. The helicopter is now equipped with a multi-sensor, multi-spectral "perception system" (you can see some of the sensors below, on the nose).
SARA S-76 (Photo: Sikorsky)
Since the beginning of the year, SARA has been flying "open loop" (with a pilot in control) using the sensors to collect data to validate the discrimination algorithms. This has involved flying the helicopter over different types of terrain and letting the autonomy system select landing zones, then flying over and having the pilots select landing sites...and usually finding they agree with the system, Sikorsky says.
The modified S-76 now has its optionally piloted vehicle (OPV) experimental certificate from the FAA (one of only a handful issued so far) and Sikorsky can begin "closed-loop" flight tests, with the autonomy system in control. Normally based in West Palm Beach, Florida, SARA will be flown around the "more interesting" terrain of Connecticut and New York to test the system in forest, mountain, lake and ocean environments.
Sikorsky is building up to using SARA to do end-to-end demonstrations of fully autonomous missions such as cargo resupply and medical evacuation. Its end goal is an FAA-certifiable autonomy system, but along the way Sikorsky plans to spin off autonomy "applications" that can be loaded on to existing helicopters - the first of these to be FAA-approved is a rig-approach app now operational in the S-92.