Volvo explores road-integrated magnets for autonomous cars

March 13, 2014 by Nancy Owano report
As a potential key to the implementation of self-driving vehicles, Volvo Car Group has completed a research project using magnets in the roadway to help the car determine its position. Incorporating the technology in preventive safety systems could also help prevent run-off road accidents. A pattern of round ferrite magnets (40x15 mm) was located 200 mm below the road surface. The test car was equipped with several magnetic field sensors.

( —Volvo has been testing the efficacy of magnets to keep self-driving cars moving safely on the road. The idea is for magnets to help the cars identify where they need to be in lanes. The Volvo Car Group tested how well the road magnets in the roadway can actually support accurate positioning. Project leaders described the magnets as serving up an invisible railway for position accuracy. By detecting the magnets a car can constantly adjust its path.

"We have tested the technology at a variety of speeds and the results so far are promising," said Jonas Ekmark, preventive safety leader at Volvo Car Group. He said ferrite magnets showed they are an efficient, reliable and relatively cheap solution, "both when it comes to the infrastructure and on-board sensor technology. The next step is to conduct tests in real-life traffic." How they tested: The team created a 100-meter-long test track at Volvo's testing facilities in Sweden's Hällered, which is outside Gothenburg. The team used round ferrite magnets (40x15 mm) placed 200 mm below the surface. Magnets were positioned at regular intervals, behaving as the so-called invisible railway for the self driving test car, equipped with field sensors.

Why focus on magnets? GPS positioning and camera technologies can be effective, but pose limitations in bad weather and with physical obstacles. Volvo Cars found magnets embedded in the road to be a reliable solution. They also said road-integrated magnets could contribute to more efficient use of road space, since accurate positioning could allow lanes to be narrower.

In the bigger picture, Volvo has its sights on a large scale experiment in future years, where the goal is to unleash 100 in Gothenburg in 2017. The automaker has been focusing on tests, tools and techniques that can ensure this can happen with success. Accurate positioning has been an important concern in advancing the development of . Volvo's research has been in cooperation with the Swedish Transport Administration. They likewise spoke favorably about the choice of magnets. "The test results are very interesting, especially when adding the potential for improved safety as well the advantages for the development of self-driving vehicles," said Claes Tingvall, traffic safety director at the Swedish Transport Administration. " A large-scale implementation of road magnets could very well be part of Sweden's aim to pioneer technology that contributes to sustainable mobility."

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not rated yet Mar 13, 2014
Not much use in UK due to the number of pot-holes and road-works...
5 / 5 (1) Mar 14, 2014
Anticipated cost (to install in the roadways) would be interesting. Asphalt? Concrete?
5 / 5 (1) Mar 14, 2014
If it's just a matter of drilling a tiny hole every few meters and adding a dab of asphalt over it then the cost should not be that great (Doesn't look like you'd need to rip up the entire road to install this). From the image it looks like the 4cm diameter magnets are placed about every 3 meters.

Another plus would be: it's a lot harder to spoof than optical recognition systems (where someone could drive you off a cliff by just painting the road appropriately).
On the downside: When there are roadworks with lanes being shifted or narrowed then this will require considerable additional effort or it will have to be disabled for such areas...but this is an issue that is particular to all guidance systems (optical, radar, ...) not just magnetic ones.
not rated yet Mar 14, 2014
Cool, what happens If I lay a trace of stronger magnets and make a turn over a cliff?
5 / 5 (1) Mar 14, 2014
If you want to go through that much trouble (drilling into roads) then you might as well just sabotage the car directly.
not rated yet Mar 15, 2014
That ain't the right way to go about controlling driverless cars.
5 / 5 (1) Mar 15, 2014
Ferrite magnets are mainly iron oxide Fe2O3 which is brittle. Road pounding vehicles may destroy the magnets. Also, when roads are repaved, asphalt grinders are used to smooth old surfaces, and level new surfaces. In the grinding of old surfaces, the magnets need to be eliminated, and in the smoothing of new surfaces, the magnets need to be placed after smoothing is finished. All this then leads one to ask: how much roadway will get this treatment? Just Interstates? Interstates and US Highways? Toll roads? Also: Will older cars retrofit to this idea?
5 / 5 (1) Mar 15, 2014
which is brittle

I'd encase them in a thin sheet of elastic material before putting them in (to eliminate stresses from heat/cold and vibration). Since they are placed a few centimeters below the surface of the road that should be adequate to guarantee long life.

In the grinding of old surfaces, the magnets need to be eliminated

Since they're pretty cheap replacing them would probably not augment costs much.

Will older cars retrofit to this idea?

Probably not for active guidance, as that would be a major refit, but maybe for additional warning systems (e.g. trucks for warning them when they are about to go off road)
not rated yet Mar 16, 2014
"I'd encase them in a thin sheet of elastic material before..."

Still, they would be mini-pothole makers
1 / 5 (1) Mar 16, 2014
Why not just add a certain amount of metal to the asphalt that a car could detect electromagnetically? It would get a much better picture of the entire road that way. This would be less susceptible to damage.

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