Coming Soon: Autonomous Indoor Drones at Your Service

By Mickael Viot

As the F.A.A. strengthens drone regulations, many hobbyists are moving indoors where F.A.A. regulations do not apply. But do you want a drone bumping into your walls and knick-knacks as it flies around your house? Is your drone piloting precise enough to get through doorways?

While outdoor drones don’t need pinpoint location precision — because there are no narrow doorways in the sky — indoors, a drone’s not knowing precisely where it is within inches, is considerably more problematic.

Imagine however, if one had an intelligent drone, one that knew exactly where it was at all times, and was capable of auto-pilot navigation away from obstacles — an intelligent indoor drone that could, for example, understand that when it is told to go forward straight towards a wall a few inches from a doorway, the pilot really intends for it to go through the doorway.

Drone intelligence like this is on its way to market, enabled by technologies that make drones aware of their exact locations as they fly. With drone location awareness, the sky, or maybe the ceiling, is truly the limit. Imagine drones that can follow people around taking pictures without needing to be piloted every step of the way. Or a drone that is controlled not via a joystick, but via a map, where a pilot tells the drone where to fly, then lets the drone fly itself there. Or drones flying in a pattern along a ceiling, flashing lights in rhythm with the music. These features and more can be achieved using location awareness.

The innovations don’t stop with basic drone control. Imagine a “drone wars” game in which drones move on their own around a site, playing a game with people in the area. Or a drone photographer that moves autonomously around a site taking pictures of partygoers. Or a drone that follows its owner around a site, taking pictures when asked but moving autonomously between pictures. Or a drone security guard that moves around a site unpredictably but continuously, covering a whole site in a random manner, keeping a looping video record of everything it sees.

The necessary ingredient for all of these innovations is location positioning. Indoor location is a huge area in the mobile arena right now, with hundreds of solutions racing to bring mapping and location sharing inside malls, hospitals, airports, exhibition centers and other public sites.

All of these mobile solutions for indoor location, however, suffer from the same problem: inaccuracy of at least 2 meters. The reason for this is that narrowband radio waves, such as Bluetooth, Wi-Fi and the other radios built into smartphones, have inherent limitations in measuring distance. Their waves go up and down smoothly in a way that is great for communication, but bad for measuring the precise start and stop points of the wave.

This is even more difficult to do in the presence of signal reflections and multipath effects, which are commonly found in typical environments. The reflection causes the radio band pulse to reverse itself and partially cancel out the original signal, as shown on the right. This means that interference and multipath effects will not only weaken the signal but also damage its integrity. This will likely not damage the data payload, but it will hurt the ability to measure the start and stop points of the signal.

Figure 1: Narrowband Radio in the Presence of Reflections

For that reason, most mobile solutions for indoor location measure signal strength and use it as an estimate for location, which is inherently limited in accuracy.

Another radio technology has recently reached the market, however, that delivers accuracy up to 10cm. This technology is called Ultra-Wideband radio. In contrast to narrowband’s wide radio waves, UWB transmits in short pulses that give a much clearer start and stop point to measure. Because of the shortness of the radio pulse, multipath effects will typically not overlap with the true signal, so the integrity and strength of the true signal will not be damaged.

Figure 2: Ultra-Wideband and NarrowbandFigure 2: Ultra-Wideband and Narrowband

UWB is not yet available in smartphones, but it is in chip and PCB form for easy integration into electronic products. Products using UWB have started to reach the market, including drones, home and commercial robots, robot cameras, thing finders and more.

Figure 3: Ultra-Wideband in the Presence of Reflections

Most deployments of UWB technology involve putting locators, also called beacons, at several points within the site, which then are used to locate an object moving around the site. A drone or other moving object can use UWB to measure its location from each of the locators, and from that collection of measurements, it can determine its exact location. UWB’s range of up to 300 meters means that a few locators can enable location awareness in a very large area. UWB is particularly good for indoor systems because UWB signals move through walls, so locators are not needed in each room.

Precise location awareness would also be valuable for outdoor drones. Many activists suspect that drone regulation will soon require precise measurement and limitation of the distance between a drone and its controller. Measuring this distance precisely can be challenging today, but UWB allows for measuring with centimeter-level accuracy.

Powered with location awareness, indoor drones can be programmed to follow a route around a site for security purposes, or to carry lightweight things between people — even delivering drinks in a bar or food in a restaurant. They can fly in entertaining patterns with blinking lights during parties and provide above-the-court photography at sports games. (Dare we call such a device a dronographer?) All of these applications require the kind of precise location awareness that UWB delivers.

With tags located on either a person or object, indoor drones can also fly alongside them, take messages to them, or take a picture of them on someone’s instruction. Imagine if a secretary can have a drone take papers to an executive for a signature wherever he is, or if a hospital can check on a patient’s well-being as the patient walks around. The above-the-court sports photographer mentioned earlier could track and photograph whatever player has the ball, or the star players, as they move around the field or court.

As drones spread into mass-market use, entering the home and other indoor sites, location awareness will make them much easier to control, and give them the ability to do a wide range of useful tasks. Location awareness is the key to drones moving from hobbyist toys to useful devices. 

Published Wednesday, August 10th, 2016

Written by Mickael Viot

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