IEEE Spectrum November, 2012 - 36

like elephAnTS marching trunk to tail, each vehicle in a platoon takes cues from
the vehicle just in front of it. Unlike an elephant, though, the vehicle also communicates
directly with the leader in order to anticipate any turns or braking action.

a driver finds a platoon that's
going the right way by selecting
a destination and following the
navigation system's directions.
the driver joins the platoon at the
rear, and the system takes control.

When one car leaves the
platoon, the followers
automatically close the
gap and continue until
their drivers decide to peel
off and go their own way.

5 meters
between
cars

drivers in the following
vehicles relax. When the
platoon approaches their
various destinations, each
driver pulls to the side and
drives on independently.
3 laser
beams/
sensors

79-gigahertz
radar

rubberneckinG's okay: Drivers in this five-member
platoon, led by a truck, can sit back and enjoy the scenery.
Guidelines allow for up to 10 members; any more makes it
difficult for outsiders to use exit ramps from the highway.

Clearly, passenger vehicles are on the verge of being capable
of some kind of autonomy. The question is, what kind is best?
The answer may surprise you.

of you are probably wondering. More specifically, why would
we want partially automated cars when not only Google but
also the Technical University of Braunschweig have recently
demonstrated fully automated ones? The Google project and
its German analogue, Braunschweig's Stadtpilot project, both
stem from technology developed for the 2007 DARPA Urban
Challenge, in which driverless cars navigated a 96-kilometer
course in a city setting. The fully autonomous vehicles in this
U.S. Defense Advanced Research Projects Agency competition
must deal with all possible scenarios in typical city traffic by
using advanced sensing, such as laser scanners, several radars,
cameras, and more. Great progress has been made, but the
sensing technology is not yet cheap enough for use in massmarket cars. More important, verifying this technology in all
potential traffic situations is an enormous and imperfectly
understood task.
A few years ago, my colleagues and I at Volvo asked ourselves how we could build on our adaptive cruise control
system to give a car full autonomy. We realized that the chief
problem lay in making sure that such a system would be utterly
36

NA * iEEE SpEctrum * NovEmbEr 2012

safe. Just to verify Volvo's pedestrian detection with fully automatic braking had required driving more than 500 000 km
and collecting more than 3 terabytes of data (mostly to confirm that the risk of inadvertent braking would be acceptably
low). To ensure that an autonomous car would almost never
make severe mistakes, no matter what the weather and traffic
situations might be, would be vastly harder. We concluded that
such a fully autonomous car would, for now, be a step too far.
To advance the state of the art, we decided to come up with
an intermediate goal. We quickly focused on the concept of
platooning, which gives the lead driver responsibility only in
the middle part of the trip. In this scheme, the person behind
the wheel of each of the following cars does all the work at
spectrum.ieee.org

VolVo (5)

What about GooGle's self-drivinG cars , some

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Table of Contents for the Digital Edition of IEEE Spectrum November, 2012