A sensor due for launch early next year allows small drones to sense and avoid obstacles with the aid of quantum film.
The drone revolution could see fleets of uncrewed aerial vehicles crisscrossing cities delivering pizza, cleaning windows and inspecting infrastructure. But this will only be possible if they can avoid trees, buildings and other hazards autonomously while flying at speed.
InVisage Technologies of Menlo Park, California, has built a low-cost sensor that can rapidly detect obstacles up to 20 metres away, using a technique called structured light. The SML-20 projects laser dots that are distorted by any object they strike, allowing the sensor to infer the location and distance of obstacles ahead.
Previous structured-light sensors have not worked well in daylight. Like the spot from a flashlight, the projected pattern is lost in the background glare, and a laser bright enough to be detected in full sunlight would not be safe for human eyes.
The new sensor solves the problem by using an infrared pulsed laser, which operates at a wavelength at which water vapour absorbs most sunlight before it reaches ground level, reducing the glare.
The laser light reflected to the sensor is then detected by a layer of film made of quantum dots – nanoscale semiconductors engineered to react to specific wavelengths of light. These quantum dots are five times as sensitive as the silicon-based detectors used in other sensors, enabling them to pick up reflections from a lower-powered laser.
According to programme manager Jennifer Lillie, the sensor detects obstacles 20 metres ahead at 30 frames per second. This is enough for commercial quadrotors moving at their top speed of 70 kilometres per hour to change path or decelerate to avoid collision. Lillie describes the sensor as “biscotti-sized”, making it suitable for small drones.
David Andrews, who leads the nanophotonics group at the University of East Anglia in Norwich, UK, says this approach is credible, but might have problems in conditions such as snow.
InVisage is in discussion with partners to put its sensor on consumer and commercial drones from next year. Watch out for flying pizzas.
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