Accelerometers for Airbags
A family of high-g acceleration sensors able to detect rapid deceleration of vehicles during a crash has been developed by STMicroelectronics (www.st.com). These "AISI DS" peripheral-sensor accelerometers provide single-axis, in-plane motion sensing from ±20 to ±400 g. An on-chip interface converts the deceleration data into a high-resolution bit stream that is transmitted to the microcontroller chip, which can deploy the airbags in milliseconds. Additionally, the accelerometers function within an extended temperature range, from -40 to 125º C.
Data Delivery at Mach 1
Conventional air bag sensors measure changes in acceleration or air pressure for deployment. But Continental has developed a "Crash Impact Sound Sensing" technology that measures structure-borne noise generated in a collision. "Just like a seismograph that measures vibrations when layers of the earth move in an earthquake, Crash Impact Sound Sensing measures sound waves," explains Dean McConnell, head of business development for Continental's North American Passive Safety Active Driver Assistance Business Unit. "Then the collision is analyzed and evaluated within just a few milliseconds."
Continental estimates that the technology delivers crash data at the speed of sound, outperforming conventional sensing technology by 15 milliseconds. "Every millisecond counts when it comes to optimizing crash protection," says McConnell.
Protection for Pedestrians
Technology may not be able to completely prevent pedestrian/car accidents (it's estimated that 11 people still die each day from such collisions), but it can help minimize injuries. That's the thinking behind the development of TRW's "Pedestrian Protection System." The system consists of three remote sensors embedded in the front bumper that transmit acceleration signals to an electronic control unit (ECU). If the system detects the vehicle has struck a pedestrian, hood-lifter mechanisms located on the underside of the hood are immediately triggered to create space between the hood and the structures in the engine compartment. This enables the hood to absorb the impact of the crash, giving pedestrians a more forgiving surface compared with the hard engine components below it. The system is designed to be integrated across a wide range of vehicles.