Volvo's attractive proposition for magnets to keep cars in lane

The low-cost magnets could eventually be used to augment safety systems such as GPS and cameras in autonomous vehicles, Jonas Ekmark preventive safety leader at Volvo Car Group told The Engineer.

The idea to use permanent magnets as a positional aid came from an American project in the 1990s.

He said: ‘What we’ve done…is another implementation of it using less expensive magnets, less expensive sensors and…microcontrollers to see whether we can get it to a reasonable cost level and still achieve reasonable performance.

‘We think of the magnet system as [providing] additional information that makes the positioning system of the vehicle more reliable and dependable, but not as a single source [for positioning].

‘We’d use it together with GPS and [an] inertial measurement system and wheel rotation sensors and possibly a detailed map that is correlated with sensors like radar and cameras in order to have a really high precision, dependable positioning system.’

To test the idea, Volvo Cars’ research team created a 100m long test track at its facilities in Hällered outside Gothenburg where a pattern of round ferrite magnets (40x15mm) was located 200mm below the road surface. The car was then equipped with several magnetic field sensors.

According to Volvo, the research programme was designed to evaluate crucial issues, such as detection range, reliability, durability, cost and the impact on road maintenance. Ekmark said that the sysem wasn’t connected to a steering controller, although that is a long-term aim of Volvo Motor Group.

He added: ‘The car isn’t trying to hit the line of the magnets exactly, the magnets would be positioned in a pattern that can be used for positioning…then the car would use the map and the features of the map like lane markers and so on in order to steer and…stay on the road.’

Autonomous driving

The current system could be incorporated in magnet-based positioning in preventive safety systems that help prevent run-off road accidents. Similarly, the magnets could facilitate accuracy of winter road maintenance, which in turn could prevent damage to snow-covered objects, such as barriers and signs, near the road edge.

The technology does, however, have potential longer term potential in autonomous vehicles and Volvo already has an experiment lined up that will see 100 self-driving Volvo cars using public roads in Gothenburg.

‘Depending on the results of the pilot tests we will expand and try to industrialise the [autonomous car] concept…as soon as we can,’ said Ekmark. ‘I would hope there’s a product on the market in less than 10 years.’

Dubbed ‘Drive Me – Self-driving cars for sustainable mobility’, the Gothenburg autonomous vehicle road trial is scheduled to start in 2017.