Unprecedented Safety, Courtesy of SensorsFebruary 1, 2006 By: Barbara G. Goode, Sensors Sensors
Savvy sensor buyers watch the automotive market. That's because this cost- and reliability-conscious industry makes tough demands of sensor developers—demands that ultimately benefit other applications. And this is car show season, so it's time to pay attention.
Aspen Exceeds Requirements
Of course all the basic mechanical processes of cars have been instrumented for years; today, sensors are enabling advanced safety. Chrysler's safety claim (that its first SUV, the 2007 Aspen, exceeds government and industry requirements) wouldn't be possible without sensors. In the Aspen, they keep side-curtain air bags deployed longer in rollovers, and monitor vehicle attitude and lateral force to estimate rollover potential (alerting the electronic roll mitigation system to trigger engine torque reduction and apply a short burst of full braking to the appropriate wheel).
Other sensor-dependent highlights of the Aspen include a back-up detection system in order to "see" items in the driver's blind spot when in reverse, an advanced multistage air bag system that inflates with a force appropriate to impact severity, and brake assist that senses panic braking and takes over for the shortest possible stopping distance. Sensors in the seat belt system include constant force retractors, which release webbing in a controlled manner during severe impact, and pretensioners that remove slack from belts during collision.
Active for S-Class
The Mercedes S-Class showcases new "active safety" features, including intelligent electronic brake and driver assist systems. The driver assistance system for adaptive cruise control (ACC) maintains distance from the vehicle ahead and ensures the necessary safety interval. The driver sets the desired speed, and once a vehicle appears ahead, ACC is on alert: sensors recognize changes in distance much faster than the driver, and, when a rear-end collision threatens, brakes immediately.
The brake control system uses four pressure sensors in addition to the master cylinder pressure sensor, allowing infinitely variable valves to provide sensitive brake pressures for improved forward and side-to-side dynamics. This, says DaimlerChrysler, translates to shorter stopping distances, barely perceptible braking intervention, and improved driving stability in hazardous situations.
Power Management Play
With more electronics in vehicles, power management is key. That's what's behind Microchip Technology Inc.'s new agreement allowing BMW access to its patents covering the use of microcontrollers/microprocessors in battery-monitoring sensors (including conventional 12 V vehicles). Microchip also manufactures components used in power sensors, including voltage regulators, memory chips, and advanced microcontrollers needed for data transmission. The integration of digital components with traditional analog current sensors is the subject of the licensed patents.
Microchip hopes this move will expand the use of integrated current sensors in all automotive designs. "BMW is a leader in the use of this type of sensor, and we expect to see other automakers follow their lead," the company says. (www.microchip.com)
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