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Keeping Tired Drivers Alert :: 11 March, 2007
AFTER a tough week at the office, the highway stretches ahead of you. The car is warm and the engine hums. Your eyelids slowly close.
And then, there’s a sudden puff of air on the back of your neck. The steering wheel vibrates in your hands and a buzzer sounds. Your car is waking you.
The car has been watching your face and, through the steering wheel, feeling your pulse. It knew you were about to fall asleep.
Indeed, falling asleep at the wheel is not uncommon. The National Highway Traffic Safety Administration said in a 2002 report that an estimated 1,500 people a year were killed and 71,000 injured in more than 100,000 crashes caused by fatigue. The study covered the 1989-92 period, the latest for which numbers were available.
Think of it this way: Drivers often close their eyes for up to three seconds at a time as drowsiness approaches. At 70 miles an hour, that’s like driving the length of a football field with your eyes closed.
“This whole issue is sort of a symptom; people are busier than they ever have been, they spend more time on the roads, they’re struggling to keep up, they spend more time behind the wheel and they’re exhausted,” said Jonathan Adkins, spokesman for the Governors Highway Safety Association, based in Washington.
Ksenia Kozak, a Ford biomechanics engineer with expertise in the way people connect to technology, said we all might nod off to some extent when we’re driving long distances. The cause is something most of us do: shifting our internal clocks by working extended schedules that violate the day-night cycle, shorting ourselves on sleep and undertaking critical tasks like driving at a time when the body just wants to snooze.
At Ford, Dr. Kozak led a study last year of sleep-stressed drivers in a simulated Volvo in the Virttex (Virtual Test Track Experiment) simulator. The drivers, deprived of sleep for 23 hours, drove for 3 hours.
Dr. Kozak’s team found it possible to cut incidences of lane wandering in half by giving drivers an alert when the car was about to stray. She said the best warning was one that vibrated the steering wheel while also turning it slightly in the correct direction.
Interviewing the drivers, Dr. Kozak said she found that most of them were honest about how drowsy they felt at various times, but not very accurate about how they were performing. Sleepy drivers characteristically overestimated their alertness and abilities, she said.
Automakers and traffic safety experts have long sought a cure for the drowsy driver, using both low- and high-tech systems. The problem has been that low-end technology, like a wearable device connected by wires that would sound a buzzer when a driver’s head flopped forward, was cumbersome and ineffective, while high-tech systems like one that used infrared beams to measure head-nodding were too complex and pricey. The solution has been physical, installing rumble strips and marking lanes and center lines using raised “Botts Dots” to give a thumping-tire warning, a potential last-chance reminder. These passive measures have reduced crashes caused by cars wandering off the road by 20 to 50 percent, according to the Federal Highway Administration, but technology companies are looking to actively warn drivers even earlier.
Today, with tiny computer-chip-based video cameras and in-car software, automotive suppliers may finally have the technology riddle solved to create systems that could be produced in the next decade.
Among them, the Denso Corporation of Japan showed its air-puffing, wheel-vibrating system as a concept display during the Detroit auto show. Siemens VDO of Germany has been developing a system meant initially for commercial truck fleets that would watch truckers’ eyes for the first signs of sleepiness, then issue a warning.
Eyelid flutter is not the only detection option, said a spokesman for Bosch, the automotive supplier. It has been developing a system that monitors the steering wheel and pedals for lapses typical of the onset of sleep. Other companies, including I.B.M., are working on variations of the systems.
Some smaller manufacturers, like AssistWare Technology and Attention Technologies, both of Pittsburgh and both building on research from Carnegie Mellon University, are selling aftermarket camera-based systems.
Douglas Patton, senior vice president for Denso in North America, said the key to any system was not so much the type of warning it gave as the way the system caught a driver drifting off.
The systems build off work already done for new lane-departure warning features being developed by many automotive electronics suppliers. Those systems use a forward-looking camera to track lane markings and pavement edges. If drivers fail to use the turn signal but appear to be wandering from their lane, the lane-departure system warns them. The most advanced systems use electronic power steering to push the steering wheel slightly in the safe direction that would keep the car in its lane, an interaction called haptic feedback.
Drowsy-driver systems use a similar infrared camera pointed at the driver’s face. The camera may be hidden in the instrument cluster or peer from the rear-view mirror, but in each case it activates when the car ignition is turned on and measures the driver’s behavior. A computer program running in the car’s electronics system sets a virtual box around the driver’s head, counts and times eye blinks, and in some cases memorizes the driver’s expression, especially the lips and corners of the mouth.
During the drive, those measurements are compared with later behavior. As people begin to drowse, experts said, their eye-blinks slow down, there are fewer of them and the eyes stay closed for a longer time.
Other drowsiness signals can also be easily detected. Muscles that control facial expression become relaxed, lips flatten and mouth corners slacken. The head nods.
Interpreting the signals automatically requires engineers to develop computer algorithms that are reliable.
“We’ve been working on this for approximately four years in prototype development,” said Ron Cook, account manager for the Siemens VDO safety and chassis electronics division. “We’ve seen strong interest both here and in Europe, though not necessarily to put it in the vehicles in the next model year.”
Mr. Cook said Siemens wanted to offer the system for monitoring drowsiness, but leave it up to the automakers to choose how that system interacted with drivers.
Siemens would like to package the system in a suite of safety features the company calls pro.pilot, which would also include adaptive cruise control, which uses a laser camera to monitor traffic ahead and keep vehicle spacing safe; a lane-departure warning system; and blind-spot monitors. Such integrated systems could help cars compensate for driver inattention, but still leave the driver in ultimate control of the vehicle, Mr. Cook said.
Most experts said that the first high-volume users of drowsy-driver warning devices would be commercial trucking fleets. Dr. Paul Green of the University of Michigan Transportation Research Institute in Ann Arbor said fleet operators could both afford and enforce the use of such systems.
“If you have a truck that’s fairly expensive, it’s not hard to justify the additional cost for the drowsy-driver monitor,” he said.
Dr. Green said he expected that once fleet data began to show the effectiveness of the systems, it would be easier to convince independent truckers and car owners to adopt the devices. He said car buyers now looked for similarly innovative safety technology once considered too expensive or invasive for the private market.
“We’re really starting to think hard about using technology to prevent crashes,” he said. “Stability control, I think, is the shining example. It’s kind of a realization that we’re beginning to approach the limits of what we can do with passive safety.”
(In Pic: PREVENTING A NIGHTMARE Denso showed its drowsy-driver monitoring system at the Detroit auto show. )
Release link: http://www.nytimes.com/2007/03/11/automobiles/11WAKE.html?_r=1&oref=slogin