It's not drone technology that's stopping you from being able to get a burger or a beer flown over to you by drone – it's aviation law. But this extraordinary piece of technology might just give UAVs the sense-and-avoid ability they need to satisfy the FAA and open up the skies.
Under FAA law, unmanned aircraft can't fly beyond the line of sight of their pilot. That's why you can't get Amazon to fly you a book yet, or get a pizza air-dropped into your back yard. And before the FAA relaxes that law, they're going to need to be convinced that drones can sense and avoid other air traffic far better than they can now.
That's going to require some next-level sensor technology; while some consumer drones are starting to gain the ability to see obstacles and react to them, it's all very close range and unreliable. Before there's commercial quantities of drones sharing airspace with single engine aircraft, there needs to be high grade sense-and-avoid technology to detect and track other aircraft from far enough away to make sure they can keep a safe distance. Even a small drone can take a plane or helicopter down; this needs to be technology you can stake lives on.
Groups like the RTCA are working on standards for this stuff up in commercial airspace over 10,000 feet. In order to get a Predator drone flying around on border security missions, they've proposed that UAVs need to be able to see other aircraft at 6.4 nautical miles away – that's 12 kilometers – with a field of view of 220 degrees horizontal by 40 degrees vertical, and they need to be able to track and update the position of multiple aircraft at least once per second.
"They've built it," says Eben Frankenberg, founder and CEO of Echodyne, a metamaterials radar startup just outside Seattle, Washington. "They've been able to build a radar that goes in the nose of the Predator, that meets these specs. It costs half to three quarters of a million dollars, weighs 50 pounds, uses 600, 700 watts … These are all ballpark numbers but they're pretty close.
"This is obviously only going to apply to large UAVs, you need a huge aircraft just to carry that kind of sensor payload. But what they're gonna do next is try to shrink these requirements down to the right size for small drones that are flying between 500 feet and a few thousand feet.
"You'll have small drones in that airspace, interacting with single engine aircraft. Uber's Elevate thing, Airbus is working on stuff in that space. The delivery drones, although they've been talking about flying under 500 feet, and a bunch of inspection drones for pipelines, power lines, railroads …
"This is where we come into play. Can we take this big, expensive military grade sensor they're using in the predator, and build something that has the right size, right price, right performance for small drones … And that's what we've done."
Echodyne has come up with a massively simplified, miniaturized and extremely cheap version of an aerial radar system. The whole thing's not much bigger than an iPhone 6 Plus, and by the start of 2017 it'll go on the market, giving UAVs the ability to see and track aircraft 3 km (1.86 mi) away, with a field of view around 120 degrees by 80 degrees. It can scan its entire field of view once a second, and get updates on tracked objects 5 times a second. The whole thing weighs under 750 grams (1.65 lb.), and uses around 30 watts of power.
It's just completed and filmed a test flight with a restricted version of the technology. Check out the video below to see how clearly the radar sees over long distances, and how well it tracks other aircraft, even ones that move erratically like multicopters can.
To understand the achievement here, you need to know a little about radars, Frankenberg explains. "The classic radars are these big rotating metal dishes; the metal dish creates a pointy beam and you can steer the pointy beam around by spinning it.
"The military in the 60s started building phased array radars, which are fixed and can steer the beam electronically without moving parts. And they can do it almost instantly, from any direction to any other. If I'm tracking a fighter on my left, and one shows up on my right, I can bounce back and forth between them. Very sophisticated technology, very expensive and that's what the Predator drones will be using.
"We've come up with a way to make something essentially the same, similar performance but not as high end. Fast electronic scanning from any direction to any other, cheaply and in a small package.
"The way phased array radars are built, they have antenna elements spaced at half a wavelength each, and they force a phase change at each antenna element, and that phase change pushes the beam one direction or another across the face of the antenna.
"We use much finer spacing in our metamaterials approach, so we have a lot more elements in our antenna design. But we don't actually need any phase shifters. That's the giant magic. We achieve the equivalent of a phased array radar, without any phase shifters.
"The good news is, it's very easy for us to manufacture, so we can make these things relatively cheaply. Now, people hear the US$10,000 price point for these things and think that's a lot of money. But we're building them in handfuls of units. Tiny volume, that's the only reason it still costs that much. The dollars will go way down."
Echodyne has been in discussions with the FAA and NASA, hoping they'll soon put together a specification for a radar system that will allow unmanned flight beyond line of sight.
"The guy who used to run the UAV office to the FAA is an advisor to us now," says Frankenberg. "He thinks this is absolutely the kind of technology that's going to open up the airspace. Over the years, they've looked at electro-optical, infra-red, LiDAR systems, computer vision systems, and they've basically said radar is the thing that works. It works in all weather, it works in long ranges, it measures the location of the target directly, it measures velocity directly. He thinks radar will be the required technology. They frankly didn't think anyone could build one small enough, cheap enough or light enough.
"Our hope is that a group like the RTCA will come up with a standard, but that in the interim the FAA will start opening up certain areas and certain exemptions.
"We're talking to a lot of companies that are interested in beyond-line-of-sight operations. Their thoughts are pretty similar to ours: hey, let's get our hands on this thing, start testing it, start proving that we're detecting aircraft out at ranges as good as what a pilot can see or better, and let's take that forward to the FAA.
"For now, we'll be selling a lot of systems to people who want to start testing it, potentially getting aircraft certified to fly it, and asking for exemptions. It's gonna take a while for big volumes to develop, but if we don't get it out there, it'll just continue to be delayed. Hopefully we can help bring the regulations along more quickly."
Of course, nothing moves quickly in aerospace law, where regulators are acutely aware that every tiny step could put lives at risk. But there's a lot of industries wanting to move forward in this space, and Echodyne's clever miniature radar could be a very significant piece in the puzzle.
Source: Echodyne
