IEEE Spectrum October, 2007 - 9

Cars Get Street Smart

no thanks to DarPa

"Robot Cars Drive Themselves!" Pretty
grabby headline, right? Throw in a few
million dollars, a lot of publicity, and
you've got a great story. The TV footage
is compelling: brightly colored vehicles
without drivers, bristling with cameras
and sensors, driving themselves over
dunes, down rutted trails-and, late
this month, through simulated suburbs
and city centers, in the US $2 million
DARPA Urban Challenge.
There's just one problem with the
imagery: the technologies likely to win
the Challenge-those expensive cameras and sensors-probably won't be the
ones that let future passenger vehicles
"drive themselves." Instead, automakers
expect that cars of the future will pay
less attention to the lay of the land and
more to each other, informing other
vehicles about what they're doing several times each second by transmitting
data that cars today already gather, via
cheap wireless transponders roughly
equivalent to your US $40 Wi-Fi router.
DARPA's interests are not in replacing
commuters but in providing new and better technology for waging war. The appeal
of an autonomous tank or rocket launcher
is obvious: without soldiers inside, the
potential casualties are reduced to zero.
And the Department of Defense is under a
2015 deadline for making 30 percent of the
U.S. military's land vehicles autonomous.
The challenge is substantial. An
autonomous military vehicle must negotiate every kind of terrain: sandy desert,
muddy forest, and dense urban core. To

IEEE Spectrum | October 2007 | NA

a tank, everything is a potentially hostile obstacle. Aside from its own location, tracked via the Global Positioning
System, it has to figure out where everything in its surroundings is in real time.
Passenger cars, on the other hand,
operate in far more limited circumstances:
they stay on roads, almost all paved. They
have no need to hide themselves, operate
stealthily, or attack other objects. (In fact,
making themselves known leads to avoidance, and hence safety.) And there are
250 million vehicles in the United States
alone, according to the U.S. Bureau of
Transportation Statistics, so traveling at
high speeds among many adjacent moving
objects with constantly changing trajectories is crucial.

Modern cars are stuffed with microprocessors and electronic control units
that process data from a huge variety
of sensors in the engine, transmission,
suspension, and other systems-and
then deliver the right blend of performance, fuel economy, and safety.
Already, many traction-control systems
simply ignore what drivers ask the car
to do if the actions would cause the car
to skid. Their sensors, though, are limited to the mechanical phenomena the
car itself is experiencing.
Several safety systems have now
added environmental data to the mix.
Adaptive cruise control, from MercedesBenz and others, is one. It uses radar to
calculate the distance to the car ahead
and that car's velocity and adjusts its
own speed to maintain a safe distance
at all times-braking right down to a
standstill and then accelerating back to
highway speeds.
Another is the Volvo Blind-spot
Information System (BLIS), which scans
the area around a car's rear corners
with side-mounted cameras and alerts
the driver if there's a vehicle present. A third is Infiniti's Lane Departure
Warning system: it calculates the edges
of the lane from images captured by a
video camera behind the windshield and
alerts the driver if the vehicle is about
to drift too far.
All of these systems still presume a
vehicular environment that's mute. And
that's one thing that will change over the
next 10 years. Several initiatives around
the world are considering standards for
vehicle-to-vehicle (V2V) communications,
in which new cars would be fitted with
low-cost, short-range wireless transmitters. They would continuously alert sur-

ALL STOP: Vehicle-to-vehicle communication
like General Motor's V2V technology keeps
cars from crashing.

www.spectrum.ieee.org

tOP: StANFOrd rAcING tEAm;
bOttOm: GENErAl mOtOrS

NEWS

THE ARMY YOU WANT: Stanford
University's Junior will compete in
DARPA's Urban Challenge this month.

http://www.spectrum.ieee.org

Table of Contents for the Digital Edition of IEEE Spectrum October, 2007