(Relaxnews) - Can magnets help autonomous vehicles stick to the road? Volvo seems to think so and has just completed a research project in its native Sweden that integrated them into the road surface to help cars identify where markings are and to stay in lane.

As such, magnets could be a potentially simple and very cost effective solution to an often complex problem: communicating to self-driving vehicles where the road is and where it is going.

Existing solutions, be they GPS positioning, cameras, batteries of radar or laser sensors, are all effective, but they are also more expensive and each has limitations. Poor weather or poor light can impinge on a camera's performance, whereas a GPS system can lose the signal.

Volvo's project, carried out in collaboration with the Swedish Transport Administration (Trafikverket), took small magnets, measuring just 40x15mm, and embedded them in a pattern 200mm below the road surface on a 100-meter stretch of road. It also fitted a car with magnetic field sensors.

"The magnets create an invisible ‘railway' that literally paves the way for a positioning inaccuracy of less than one decimeter. We have tested the technology at a variety of speeds and the results so far are promising," says Jonas Ekmark, preventive safety leader at Volvo Car Group.

But as well as guiding self-driving cars, the magnets could be used for other safety purposes. For example, during severe snowfall, they would help to indicate where road lane markings are to any type of car fitted with sensors.

They could also be used as an automatic switch for activating a car's safety systems -- for example, if it were to leave the road altogether in the course of an accident. And by using magnets as a guide, it is conceivable that road lanes could be made narrower.

"Our experience so far is that ferrite magnets 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," explains Ekmark.

Claes Tingvall, traffic safety director at the Swedish Transport Administration, agrees: "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. A large-scale implementation of road magnets could very well be part of Sweden's aim to pioneer technology that contributes to sustainable mobility," says Tingvall.

The tests form part of Volvo's large-scale autonomous driving pilot scheme, which is currently underway in Gothenburg and will eventually see 100 self-driving cars taking to the city's roads for comprehensive testing in all typical driving conditions.

"Our aim is for the car to be able to handle the driving all by itself. Accurate, reliable positioning is a necessary prerequisite for a self-driving car," explains Ekmark. He adds: "It is fully possible to implement autonomous vehicles without changes to the present infrastructure. However, this technology adds interesting possibilities, such as complementing road markings with magnets."

As well as Volvo, Nissan is currently undertaking similar large-scale testing of its autonomous driving technology and both companies are dedicated to rolling out self-driving features to production cars by 2020