Visions of self-driving cars have been with us for generations, and today’s engineers are getting very serious about developing the technology and infrastructure that will someday make self-driving cars a commercial reality.
Volvo thinks it has an answer that not only works but also is feasible in terms of cost: Roads embedded with small magnets.
The Volvo system combines magnetic roads with vehicle-mounted sensors and computing power to accurately and reliably guide cars down the road. A wide variety of approaches are being explored to speed up the commercial viability of autonomous vehicles. Constructing roads embedded with magnets offers several advantages, according to Volvo.
Image by Volvo via Wired.com
The low-tech nature of magnets is one of the reasons Volvo was originally drawn to the idea. Other ideas often rely on advanced data networks to provide location guidance. Of course, people who have spent almost any time at all on the Internet or on an office LAN knows that networks can go down.
Magnets, though they may eventually lose their magnetism, never suddenly “go down.” Also, magnets work in all kinds of weather conditions. Cover a magnet with snow, and it’s still magnetic, unlike some of the experimental visual sensing systems.
Further, outfitting our roads and highways with magnets, while not cheap, doesn’t require any advanced engineering or special materials.
The hang-up with using magnets for location guidance is in the technology required to sense the magnets. Currently, magnetic sensors can only take about three readings per second and need to be very close to the magnet—within just a few centimeters—in order to sense it. Volvo engineers determined that it would require 400 readings a second to navigate a car traveling about 90 miles per hour.
They solved the problem by building a five-sensor rig, with each sensor made up of 15 smaller Honeywell magnetoresistive sensors. That may sound rather complicated, but Volvo says that if they manufactured 50,000 of those rigs each year, the cost would only be $109 per rig.
The first tests took a magnetic-sensor-equipped Volvo S60 over 100 meters of roadway with 100 embedded magnets. The system could find the S60’s position within 10 cm while traveling at a speed of about 45 mph. They scaled it up by gluing magnets on a paved road. That gave equally accurate readings at speeds over 90 mph.
Not everyone is stuck on the idea of magnets. The price tag to upgrade highways with magnets is almost $40,000 per mile, and there would be significant ongoing maintenance costs. Some other approaches don’t require major infrastructure overhauls. Google is among the leaders in developing this technology. Its system uses GPS data, computers and sensors for driver-less navigation. However, all of that on-board equipment costs roughly $250,000 at today’s prices. Some states are beginning to license experimental automated vehicles.
There are other systems being explored as well. Analysts predict that the private sector will eventually decide the winner as it did with other competing technologies such as Blu-Ray and HD-DVD.