Electronics Spur Active Auto Safety

Sept. 16, 2004
Automotive engineers are looking beyond air bags and seat belts to electronics for better, more-sophisticated safety systems.

Electronics spur active auto safety

Sideview-mirror cameras on 2005 Volvos warn of vehicles in the driver's blind spot.

Volvo's BLind spot Information System (BLIS) uses a compact imagingarray camera mounted below each sideview mirror. An LED in a triangular area on the window frame alerts the driver to a vehicle in the blind spot to the rear and side.

The camera module features a National Semiconductor CMOS imaging array. A Continental TEMIC processor uses a Texas Instruments 350-MHz BGA DSP to determine if a vehicle is lingering in the driver's blind spots.

Automotive safety has hit the wall. That was the consensus of industry experts assembled by Infineon Technologies North America, San Jose, (www.infineon.com/us), in early August to discuss new electronic systems and how they can contribute to reducing highway fatalities. The point was hammered home in figures released by the U.S. Dept. of Transportation days later that showed highway deaths hovering above the 42,000 mark for 2003. That count has been more or less the same for 20 years, although the rate of deaths has plunged from 5.5 to under 1.5 per 100 million miles driven.

Passive safety systems such as air bags, which mitigate accident effects, have gone about as far as they can in preventing loss of life. But panel member Lars Lundin, vice president and general manager of Volvo's Monitoring and Concept Center, Camarillo, Calif., noted, "Air bags are not as efficient as seat belts," and deaths would drop dramatically by simply having more widespread seat-belt use. About 60% of those killed in automobile accidents aren't wearing a belt.

Electronics developers are looking at active safety systems to assist drivers in avoiding accidents altogether. These systems go beyond existing ABS and traction and stability control to allow, for example, monitoring driver functions (detection of rapid pedal movements) to prepare for emergencies (pretensioning seat belts and preliminary brake application), or provide sensing for better situational awareness.

According to panelist Richard Lind, Delphi director of advanced engineering for electronics and safety, such advancements have to be unobtrusive to the driver as well as multifunctional to lower cost. For instance, automated cruisecontrol sensors can also provide parking assistance and object detection. Sensors such as lasers, radar, or cameras for 360 coverage around a vehicle must function through a human-machine interface that is intuitive to operate and does not overload a driver, he adds. Algorithms will fuse sensor data to alert the driver. This might be via an audio cue or vibration of the steering wheel or pedals in addition to a dashboard or windshield display, Lind notes.

Specific developments highlighted by the panel included vision systems using compact cameras and advanced processors. Engineers at Volvo have introduced a sideview-mirror-mounted camera system on 2005 models to give drivers warning of cars in blind spots to the rear of a car on either side of the vehicle — areas often not visible in either the rear or sideview mirrors. The concept was first demonstrated on the company's Safety Concept Car in 2001 (www. conceptlabvolvo.com/us/scc).

The BLIS (BLind spot Information System) features CMOS imaging-array cameras from National Semiconductor, Santa Clara, Calif., rather than radar. Transmitting radar systems can have EMI concerns, according to project engineer Bjorn Hellden. Radar would have been more difficult for the engineers to package in the sideview mirrors, he adds. An extra radar sensor was also needed in the rear bumper to calculate relative vehicle speeds.

The cameras at the base of each sideview mirror look into a detection " window" or warning zone 30-ft long by 10-ft wide. This field of view was determined by calculating the blind-spot area for a driver in the worst seating position using a flat, U.S. regulation driver's side mirror. (European mirrors have a convex outer area.)

Each camera images at 25 frames/sec. Array resolution is 640 X 480 pixels with the working area of the array 320 3 240 pixels. A dedicated 350-MHz DSP from Texas Instruments, Dallas, crunches the image data using proprietary image-processing algorithms. Hellden says the pattern-recognition algorithms look for the same pattern (including ones for motorcycles) in the warning zone in three consecutive images. The rate of change between pictures is used to determine the location and relative speed of any vehicle within the window, according to Volvo's Lars Lundin. At night, the cameras detect headlights rather than vehicle-shape patterns.

If a vehicle is within the detection area, the BLIS processor illuminates an arrowshaped LED light on the inside window frame inboard of the mirror. The system software does not issue alerts for vehicles overtaking at greater than 43 mph, which quickly transit the blind spot. Warning is also not given if the BLIS-equipped car passes another vehicle at more than 12 mph, where the driver sees the slower car quickly passing through the warning zone. The controller does not activate the system until the car is moving at speeds greater than 6 mph.

Another vision system developed by Delphi, Kokomo, Ind. (www.delphi.com/ products/auto), positions its camera inside the vehicle. This tracks the driver's eye movement to determine various behaviors that may impact driving ability and safety.

Based on university research, eye tracking is a nonintrusive way to measure physiological states such as blood-alcohol content or intoxication, notes Delphi's Richard Lind. He points out that modern, affordable processing and computer power make possible not only being able to track eye movement but determine characteristic behavior patterns. Ten years ago, such vision-based systems may have required multiple cameras, Lind notes.

The first application of the Delphi system will be determining drowsiness of truck drivers. "We think eye tracking is a significant way to tell if a driver is drowsy by monitoring blinking, stare, gaze, and where the driver is looking," says Lind. With auto-initialization and calibration, no driver interaction is required for the system to work. The company is reluctant to provide further system details at this time, but notes it is designed to function under all lighting conditions and the "normal range" of glasses worn by drivers.

The Delphi eye-tracking system is expected to be available as an aftermarket trucking-industry technology in the fourth quarter of 2005. While fatigue monitoring will be "the first product feature," other applications will likely follow if this one is successful.

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