The Unlikely Technology Helping Autonomous Cars See

Old-school paintmakers are key in enabling sensors to detect oncoming vehicles.
Photographer: Joanna McClure for Bloomberg Businessweek

When Henry Ford revolutionized transportation a century ago with the mass-produced Model T, it came in just one color: black. Eager to customize vehicles to buyers’ tastes, automakers have since cranked out cars in almost every hue imaginable. Now the industry is again concentrating on its original color to address a dangerous blind spot of self-driving cars: They can’t see black very well.

Dark colors absorb light, which means the navigating lasers of autonomous vehicles don’t quite bounce off—or enable detection of—black cars. Therein lies a potential windfall for old-school companies that make paint. 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.

PPG and other companies see a lucrative opportunity in solving one of the most intractable problems of driverless technology—and a way to ensure demand for their products even as the number of cars on the road may dwindle.

Yet this isn’t just a challenge for tomorrow’s vehicles. Cars that can already park themselves, apply brakes, avoid obstacles, and find the correct lane rely on sensors and transmitters hidden in bumpers and side panels. Paints and coatings can interfere with or improve the performance of those sensors, says Barry Snyder, chief technology officer of Axalta Coatings Systems Ltd. “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.”

Still, the spread of autonomous vehicles—which will encourage more ride-sharing and potentially erode new-car sales—poses plenty of threats for paintmakers. And removing human error from driving should lead to fewer accidents, which would also mean a decline in paint sales to repair shops. For Axalta, which gets more than 80 percent of its revenue from automotive coatings, the stakes are particularly high.

But there are solid reasons for optimism: Autonomous cars may need twice as much paint, sealant, and other coatings as current ones, says David Bem, PPG’s chief technology officer. The increase will be more than tenfold if electric engines become the favored propulsion mode for self-driving cars, he says. “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.

“You’re getting the first major change to the automotive powertrain in 100 years,” says Stuart Hellring, a PPG senior scientist whose patents include the eggplant technology. “My perspective is, you’re going from onboard combustion to riding around on a coating.”

PPG Chief Executive Officer Mike McGarry appointed a special committee, reporting directly to him, to figure out new business possibilities as manufacturers from Tesla Inc. to General Motors Co. race to bring self-driving autos to market. A separate team is focusing on batteries.

So how do eggplants fit in? PPG reengineered a coatings system it originally developed to keep airplane cabins from overheating under the glare of the sun. The technology, used on aircraft since 2015, is based on the eggplant, which stays 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 company adapted the same coatings—which replace 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.

Conversations with automakers about lidar—the sensing method that uses laser pulses to measure distances—unearthed other problems PPG could work on. 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, says CTO Bem.

“Instead of one omnibus coating on a car, we might have four, five, or six different types of coatings for different areas,” he says. “As it gets more complex, it’s good for a company like us.”

PPG also is developing a bar code that can be applied to an autonomous vehicle in a color 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.

While most autonomous vehicles are being designed to communicate through radio signals, bar codes are the type of robust system that would serve as a welcome backup, says Christoph Mertz, a principal project scientist at Carnegie Mellon University’s Robotics Institute. “Redundancies are always good, especially with autonomous vehicles, because it can be deadly if there is a mistake,” he says. “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.”

    BOTTOM LINE - Because the surfaces of cars have to be detected by sensors in driverless vehicles, paintmakers have become key players in the race toward autonomous driving.
    Before it's here, it's on the Bloomberg Terminal.