The autonomous cars are coming.

It may sound like a fairly simple matter to get a car to steer and brake itself, but there’s a lot more to it than that. Virtually every aspect of the car will eventually need to be involved, including some you may not have considered: its navigation system, and its tires.

Navigation systems are already commonplace, of course, but they’re going to have to become even more sophisticated, and be updated more frequently, if they’re going to correctly send vehicles on the right path without a driver at the wheel.

“You need to know where you are and to know what’s ahead of you, and also to know where other objects moving around you are relative to the road and your car,” says Harold Goddijn, president and CEO of navigation and GPS company TomTom. “There’s a whole new technology that must come together.”

Cars that can drive themselves are already available today, including the Mercedes-Benz S-Class and Acura MDX. But these vehicles are only reacting to what’s directly around them, by using their lane-keeping ability to stay between the lines, and their adaptive cruise control to maintain a consistent distance from any vehicle in front. They can’t perform far more complicated tasks, such as stopping for a red light, turning at an intersection, or passing other vehicles on their own.

A fully-autonomous car will be able to do all of that, but it will depend on infrastructure, including an accurate navigation system. Goddijn says that such maps will need such information as where the lines are on the road, how the road bends, and know exactly, within 20 centimetres, where highway exits start and end. “All of this gives the computer in the car the information to accurately plan its next manoeuvre, and so the computer knows where it is and where it’s heading,” he says.

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Navigation maps will have to be far more accurate than they are now to handle autonomous vehicles

Making these accurate maps is only half the battle though, and the toughest part is going to be keeping them up-to-date. A driver will change his plans when a road is closed for construction or a bridge has collapsed, but an autonomous car won’t if its map says the way is clear. That’s the sort of stuff that keeps Goddijn up at night.

“We don’t drive (the routes) every week or every year, and we think the cars need to report back to us if there’s a discrepancy of what’s in our database,” he says. “We’re building a highly-automated self-improving system, based on machine learning and other technologies, that will help us to make sure the maps are accurately reflecting the reality.”

Cars already do this to some extent, Goddijn says. Initially making a map involves such things as digitizing government data, and driving the roads with mobile mapping vans. The company continues to use that when updating, but it also depends on its customers. TomTom asks users to provide feedback when something has changed, but the company also collects GPS data as vehicles are driving.

“We make traffic information based on actual movement of cars connected to the network,” Goddijn says. “It’s anonymous, but we know where they are.” The company is looking for discrepancies, such as cars driving where the map doesn’t yet show a road, or unusual traffic patterns, including cars driving a different way on a one-way street that may indicate the street’s direction has been changed.

How long it’s going to take before map infrastructure is accurate enough for an autonomous car is anyone’s guess, but Goddijn suggests it could be within the next five years.

Of course, the map is only one part of a complicated puzzle. It’s one thing for the car to know where to go, but it’s another for it to know where it needs to stop. Many vehicles already have moisture and temperature sensors, which help them figure out if the road may be wet or slippery. But they don’t know what shape their tires are in, and that’s a primary key to stopping in time.

Pirelli plans on tackling that issue with its Cyber Tire, which will not only help pave the way for autonomous cars, but is expected to be available initially on conventional vehicles as well.

The Cyber Tire system builds on the tire pressure monitoring system (TPMS) and adds sensors that can help determine how much grip the tires have. These sensors monitor such information as the lateral and vertical load on the tire, the type of asphalt it’s on, the tire’s footprint and angle, its wear, and the number of revolutions it’s making. The sensors then relay this information to the car’s computers, which in turn can adjust the cruise control and braking systems to match the available grip.

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Sensors in the Pirelli Cyber Tire will convey information about the tire’s grip

“The system is able to measure exactly the level of friction and the level of grip, depending on the tread depth and quality of tire you have installed,” says Giorgio Audisio, director of cyber technology for Pirelli. “If you are able to measure the grip, you can adjust the vehicle speed, and one function could be a safety speed limiter in very difficult conditions, when you are on a wet road, on ice, or on snow.”

The sensors relay their information in real time to the vehicle, which in turn can react almost instantly if the level of available grip changes. On a conventional car, this will include warning the driver to slow down or take extra care if necessary. On an autonomous car, information from the sensors would be communicated directly to the systems involved.

Such information will be vital, because there are limitations to how well any system can perform based on the information it has. An autonomous car will know it has to start braking when it gets close to the vehicle in front, but if its sensors aren’t aware that they must also account for worn tires or a slippery road surface, it still might not stop in time to avoid a collision. Such information could also tell the car to slow itself down in adverse conditions, or to take a curve at a lower speed than it might on dry pavement or with newer tires.

Pirelli already offers the Cyber Fleet Solution for truck tires, which measures pressure, temperature and mileage and communicates it to a dedicated reader. The Cyber Tire isn’t in series production for consumer vehicles yet, but is used on the limited-edition Ferrari FXXK racer, where it sends its information back to the driver. And, of course, when the autonomous car finally gets to the consumer level, you can expect to see something like this in it as well.