Autonomous Cars - Accident Avoidance

November 18, 2008
0812 01 Z+chevy Tahoe+carnegie Mellon University
Ralph Nader's sensationalist Unsafe at Any Speed set the auto-safety movement's course, one from which it is now about to depart. Nader espoused two radical concepts. One was what he called crashworthy cars - automobiles that sacrifice their skins for their occupants' good. The second was the use of passive restraints; the public and many government officials first learned of air bags in the pages of Unsafe.
Today, we've gone about as far as we can down those roads. In the effort to save lives and dollars, preventing cars from bumping into one another in the first place is the next frontier.
Engineers have been striving toward that end for decades. GM began investigating automated vehicle controls and built an experimental 1958 Chevrolet without a steering wheel a few years before Nader's seminal tome. In the mid-1990s, Buick modified eight LeSabres so that they could cruise in formation down a 7.5-mile stretch of California's I-15 guided solely by magnets in the pavement. Europe's $1 billion Prometheus Project for autonomous vehicles culminated with an experimental Mercedes-Benz driving nearly 100 miles on German autobahns at speeds occasionally exceeding 100 mph.
More recently, the Defense Advanced Research Progress Agency (DARPA) hosted a Grand Challenge competition to foster the development of driverless military vehicles. Teams vied for $6.5 million in prize money. At the first event, in 2004, none of the robotized vehicles completed a 142-mile desert course. The following year, five teams finished, headed by a Volkswagen Touareg prepared by Stanford University. Last year's Urban Challenge consisted of a 60-mile route around obstacles and through (artificial) traffic at a closed Air Force base. Six entrants completed the challenge, led by Carnegie Mellon University's Chevy Tahoe (pictured).
The gap between experimental autonomous cars and production models programmed to avoid collisions is rapidly narrowing. Advanced sensors and software have begun trickling down to the consumer level. For example, active cruise control systems using radar or laser sensors to trigger throttle adjustments and brake applications when the forward path becomes impeded are now widely available. The Lexus LS's Advanced Parking Guidance System uses cameras, sonar sensors, and other hardware to automatically wriggle the car into parking spaces. Infiniti's Lane Departure Prevention system - available on M, EX, and FX models - goes beyond simple wander warnings that have been offered by this and other brands; if the vehicle begins drifting out of its lane without a turn signal activated, the brakes on one or two wheels are applied to return the vehicle to a straight-ahead path.
0812 01 Z+chevy Tahoe+carnegie Mellon University
By-wire controls with at least some authority over the throttle, brakes, and steering are now commonplace. The current trend of using electric motors instead of hydraulic pressure to assist power steering is another step in the automated-control direction. Still, it's a major leap from automatic steering at parking speeds and a soft nudge of the binders to whirling the wheel and spiking the brakes to avoid a high-speed, head-on collision.
Some of the hardware required to close this gap is now in test vehicles. GM has a vehicle-to-vehicle communication system using simple and affordable GPS to sense the presence of other vehicles, whether they're in a nearby blind spot or up to a quarter of a mile away. VW's recent Passat-based iCar packs powerful computer hardware for automatic steering plus a DARPA-like camera, radar, and proximity sensors.
The most interesting iCar feature is what VW calls PyroBrake. When camera and radar sensors warn that a collision is imminent, emergency braking can be activated in 80 milliseconds by means of a pyrotechnic charge similar to those that inflate air bags. According to VW engineer Mark Gonter, this approach is more than four times quicker than other forms of panic braking. "The question now," Gonter adds, "is how to detect an unavoidable collision without any false alarms."
As the technological gap closes, a philosophical one looms. To implement collision-avoidance systems that take control from the driver and give it to computer chips, carmakers will need the National Highway Traffic Safety Administration's blessing. That may not be terribly difficult to obtain. NHTSA spokesman Rae Tyson said, "We certainly encourage development of this technology, because we believe that there are few gains left to be made by improving the vehicle. Therefore, further significant improvements in safety will have to come from helping drivers avoid collisions in the first place."

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2015 Chevrolet Tahoe

LS RWD 4-Dr Sport Utility V8
starting at (MSRP)
$46,300
Engine
5.3L V8
Fuel Economy
16 City 23 Hwy
2015 Chevrolet Tahoe