General Atomics Tests Sense-and-Avoid System
Before drones can be integrated in the national airspace, the Federal Aviation Administration has mandated that they must have a “due regard” capability that allows them to maintain a safe separation from other aircraft. Pilots in a cockpit can see the approach of other aircraft or wildlife and make split-second decisions to avoid a collision, but operators of unmanned aerial systems often may not have the same visibility. Latency in the data link connecting a drone to its pilot may also restrict the ability to maneuver the UAS in the event of a possible collision.
The Radio Technical Commission for Aeronautics formed a special committee in 2013 to develop industry standards for sense-and-avoid systems. General Atomics is part of the committee and is developing its system to meet the emerging standards, Suarez said.
“The flight testing that we’re going through right now with NASA will lead to what we’re calling a prototype sense-and-avoid system to fly in the summer of 2015,” he said. “That prototype sense-and-avoid system, which will include an upgrade to the air-to-air radar … and a lot of other kinds of system enhancements, will essentially match what the standards community is coming up with in a draft standard that’s due as well.”
The testing on the Ikhana — the name given to the NASA-owned MQ-9 — took place at the administration’s Armstrong Flight Research Center in California. General Atomics will conduct a final flight test with NASA in 2016 with a sense-and-avoid system that will verify the RTCA’s technical standards, Suarez said.
The company’s system comprises three sensors: the automatic dependent surveillance-broadcast, or ADS-B, a transponder that detects cooperative aircraft also carrying the sensor; the traffic collision avoidance system, or T-CAS; and the due regard radar, an air-to-air radar that detects aircraft that are not required to carry a transponder. Working on top of these sensors is an algorithm that takes traffic information and formulates how to maneuver away from an oncoming aircraft.
General Atomics’ Reaper and the smaller MQ-1 Predator are flown by military pilots with a stick and throttle, but can also be piloted with a human “in the loop” — someone who is not controlling every movement of the aircraft, but is determining the aircraft’s altitude and heading, for instance, he said. The sense-and-avoid system would “basically [be] doing the math for the pilot,” showing where loss of safe separation could occur.
In the case of a probable aircraft collision, it would automatically trigger a maneuver to keep the drone from hitting the other craft, but the pilot could override it if needed, Suarez said.
“Since our pilots are in the loop, they maintain the ability to take back control of the aircraft,” he said. “You can think of a number of situations where … the pilot basically has more information than the system does, so he knows, ‘OK, yeah, I’m talking to that other aircraft on the radio, I know that he’s about to turn, so I know it’s not an actual conflict or collision hazard.’”