Future Prize: radar-assisted emergency brakes

As with other systems, today's driving assistance and automatic emergency brake systems use radar. But they are a world away from the likes of those used on radar piloted ships - with their rotating antennas several feet long, mounted on tall masts.

By contrast, you would have to be an expert to spot the radar antennas in cars. They are tiny - not much bigger than a matchbox and usually hidden away - somewhere inside the radiator grill.

Entire radar installations consist of no more than a small circuit board with a tiny microchip mounted in the center. The antennas are integrated into the circuit board and are about one inch long.

"We had the idea around the year 2000 of producing radarchips using standard silicon technology, which is used to produce more or less all computer chips these days," says physicist Rudolf Lachner, while holding one of the radar devices in his hand. "The aim was to make radar cheaper and more accessible to everyone."

It was not an easy task. Radars used to be expensive and often cumbersome - only feasible for specialized users, such as in naval or river shipping, radio astronomy or at airports.

A steep curve from the 1990s

The first radars for cars appeared on the market in the late 1990s, but they did not catch on. They featured semiconductors made of gallium arsenide - a rare and rather expensive material - and it's thought that's why failed on the market.

Gallium arsenide was used in radar because it could handle frequencies of 77 Gigahertz - the bandwidth allocated internationally to road vehicle use.

"That is a frequency about 30 times higher than those used in mobile telecommunications," says Lachner. "All silicon technologies that existed more than ten years ago were designed to work only at those lower frequencies."

A traditional television set works with frequencies around 800 Megahertz, or 0.8 Gigahertz. A mobile phone goes up to 2.5 Gigahertz. This still leaves a huge gap until you get to the 77 Gigahertz required for car radar - and that's 77 billion oscillations per second.

It's all about the material

"The key for us was the introduction of a special layer of silicon-germanium on top of the silicon base material," says engineer Ralf Bornefeld. "It wasn't easy to do. But we were successful and managed to reach even higher frequencies than those possible with gallium arsenide. This was a breakthrough, and the first step towards making radar a mass-product."

Engineer Walter Hartner worked on the launch of industrial scale production of entirely encapsulated radar units at the Infineon plant in Regensburg. Hartner believes the potential for mass producing radar chips depended on the size of the silicon wafers used in production.

"It was a great advantage for us that we could use standard 8-inch production lines with the silicon-germanium wafers," Hartner recalls. "The old transistors used a 6-inch system, which made the manufacturing process much more expensive."

A new era in brake technology

In 2003, Infineon presented the first silicon radar chip to the public. In its first five years on the market, the company equipped five million cars with the new technology. By 2016, it expects to achieve the same figures in just one year. That would be ten million chips in total - two chips per car.

For traffic safety, the development of radar-based automatic emergency brake systems has heralded in a new era.

This technology is as important as the introduction of the seat belt or the air bag.

Bornefeld says cars of the future should be able to "see" in all directions, and the new chips will make that possible.

"At the beginning, our focus was on preventing collisions with cars driving in front," says Bornefeld. "That works very well now. The second step was focusing on protecting pedestrians and cyclists."

He's thinking of situations where, for instance, a truck makes a right turn but the driver doesn't see a cyclist. Or when a child runs out between parked cars.

Active security

Lives can be saved, and that at a relatively low cost. Prices for this active safety system have fallen to about 250 euros, which, if you're buying a new car, won't make a big difference.

In Britain you may even save money. Car insurance companies have lowered the premiums for customers with radar-supported emergency brake systems.

This came after a study showed that injury damages in accidents involving the Volkswagen Golf 7 were 45 percent down on similar cars without such safety features.

Autonomous driving

Meanwhile, there have been great advances in the area of self-driving, robotic cars. So how much longer will it be before we simply leave all the driving to the car itself?

Well, it's not going to happen any time soon.

Yes, radar technology can help maintain a constant distance to a car driving in front of you on the highway. And, yes, it can also handle stop-and-go traffic.

"But if we really want the cars to drive fully automatically, we'll need a lot of other extra systems," says Bornefeld. "Optical cameras can see like people. But they can have problems at night or in bad weather. Laser and radar may then be better, because they are more robust in such conditions. But they don't identify objects as well."

All this means a fully automatic, self-driving car will need much more than just radar. It will need cameras, laser, interconnected communication systems and so on. And that will make robot cars fairly expensive for the time being - as opposed to the automatic emergency brake.

The three inventors have been nominated for the #link:http://www.deutscher-zukunftspreis.de/en/news/2015-deutscher-zukunftspreis-just-few-days-away:German Future Prize# in Berlin on December 2. German President Joachim Gauck will announce the winner among three nominated teams.