An Unlikely Technology that Can Help Autonomous Cars See Better
It may be that the old-school paint makers are key in enabling sensors to detect oncoming vehicles.
A century ago, when Henry Ford revolutionized transportation with the mass-produced Model T, it only came in just one colour: black. After this, car makers were eager to customize vehicles to buyers’ tastes, car manufacturers began to produce cars in almost every hue imaginable.
The motor industry is once again concentrating on its original colour to address a dangerous blind spot of self-driving cars: The reason being, they can’t see black very well. Dark colours absorb light, which means the navigating lasers of autonomous vehicles don’t quite bounce of the body of the vehicle or enable detection of black cars.
The world’s largest producer of vehicle coatings, PPG Industries Inc., is engineering a paint that allows the near-infrared light emitted by lasers to pass through a dark car’s exterior layer and rebound off a reflective undercoat—making it visible to sensors. PPG got the idea from the purple eggplant, which uses a similar trick on farms to keep cool on hot days.
Companies such as PPG can certainly see a lucrative opportunity in solving one of the most intractable problems of driverless technology which is the sensor detection of dark vehicles. Even now, cars can park themselves, apply brakes, avoid obstacles, and find the correct lane but in order for an autonomous vehicle to do that rely on sensors and transmitters hidden in bumpers and side panels.
Many different paints and coatings can interfere with sensor detection on autonomous vehicles and this is also true in the opposite direction in which certain paints, especial black can actually improve the performance of those sensors. Chief technology officer of Axalta Coatings Systems Ltd. Barry Snyder,
“Autonomous cars create some significant issues from a paint standpoint,” he says. “But you have technology going into smart cars today that already creates challenges we need to respond to.”
It turns out that autonomous cars may need twice as much paint, sealant, and other coatings as regular combustion engine vehicles. David Bem, who is PPG’s chief technology officer said that the increase will be more than tenfold if electric engines become the favoured propulsion mode for self-driving cars.
“Even if [the numbers for] auto builds shrink because everyone is sharing cars, we still see growth. The coatable surface area goes up so much, it’s a huge difference in content for us.”
That’s mainly because the giant battery packs required by electric cars—a typical vehicle may contain thousands of small batteries encased in a metal box stretching from tire to tire, axle to axle—need heaps of special coatings for each of their components. Some prevent overheating while others keep moisture and corrosion at bay. All told, electric vehicles may require more than 1,000 square meters (10,764 square feet) of coatings, compared with about 70 square meters on a conventional car today, according to PPG. Stuart Hellring, a PPG senior scientist whose patents include the eggplant technology said:
“You’re getting the first major change to the automotive powertrain in 100 years,”
“My perspective is, you’re going from onboard combustion to riding around on a coating.”
So how do eggplants fit in? PPG developed coatings originally developed to keep aeroplane cabins from overheating under the glare of the sun. This coating technology used on aircraft since 2015, is based on the eggplant and how it can stay cool in sunny fields because its purple skin lets near-infrared energy pass through to its white flesh, which reflects it away. The coating system cut temperatures on planes’ skin by 25F, and by about 6F inside cabins, according to PPG.
The light-absorbing carbon black used in dark paints with special pigments, some made by chemical giant BASF SE, that let near-infrared light pass through—for cars. While older vehicles won’t have such detection-enhancing paint, self-driving cars also use sonar, radar, and cameras to navigate. Those technologies will help bridge the gap until the new coatings become widespread, PPG says.
The metallic sheen of some car paints can interfere with the radar systems tucked behind bumpers. So PPG tapped its Cuming Microwave unit, which specializes in radar-absorbing coatings, to find a solution. And when carmakers complained that sensors’ performance drops when they get dirty or ice over, PPG developed ways to alter the microscopic surface of coatings to repel water and mud and prevent icing. The CTO Bem.
“Instead of one omnibus coating on a car, we might have four, five, or six different types of coatings for different areas,”
“As it gets more complex, it’s good for a company like us.”
PPG is also developing a barcode that can be applied to an autonomous vehicle in a colour invisible to humans but that can be scanned by another vehicle, yielding information about make and model, as well as performance data such as braking distance. The technology also could be deployed on street signs and other road structures to help driverless vehicles navigate.
The majority of autonomous vehicles are designed to communicate through radio signals but with the invisible barcode concept, we will see quite a good robust system that would serve as a backup.
Christoph Mertz, a principal project scientist at Carnegie Mellon University’s Robotics Institute said:
“Redundancies are always good, especially with autonomous vehicles, because it can be deadly if there is a mistake,”
“Any information you want to pass around, you want to pass it around in a number of ways.”
Some solutions create other issues that need to be solved, says Axalta’s Snyder. If a vehicle is painted with a self-cleaning coating to keep sensors clear, touch-up paint won’t adhere to the surface, making maintenance and repairs more challenging. All the better for the paint companies, which will have to come up with a new kind of scratch-fixer.
“How do you make it so dirt won’t stick but you can still repaint?” Snyder asks. “This is the kind of stuff that keeps me in business.”
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