Prognosticators have talked of the day when an automobile’s various computers and sensors would work together to provide functionality greater than the sum of the parts. It appears that day has finally arrived.
The Combined Active and Passive Safety System (CAPS) from Robert Bosch Corp. (Farmington Hills, MI; www.boschusa.com) cross links the electronic controllers and sensors of existing passive and active safety system to extend the vehicle’s ability to respond to emergency situations. "Networked electronic systems reduce vehicle reaction time, provide a more accurate view of the vehicle environment, and make more effective use of the vehicle’s computing power," says David Robinson, president, Electrical and Electronics Div. at Bosch. They also move from increasing a vehicle’s crash worthiness to expanding the envelope for crash avoidance.
Full-range active cruise control (ACC) uses a radar sensor to maintain an appropriate distance from the vehicle ahead in the city or on the highway, including stop-and-go traffic. With additional software, it also can be used to recognize and react to emergency braking situations. In the first response stage, the brake pads are placed on the brake disc and the hydraulic pressure increased without initiating braking. The next stage recognizes an emergency braking situation is imminent and quickly and forcefully applies the brakes for a short duration. This causes an audible "chirp" from the tires and puts the vehicle in a nose-down attitude, which focuses the driver’s attention on what’s happening ahead of the vehicle. If the collision is unavoidable, automatic braking at maximum deceleration occurs, which reduces the stopping distance and the severity of the impact.
"Passive safety is enhanced," says Rob Lyons, engineering manager, Advanced Technology Development, "by using this information to pre-load passive safety systems like the airbag and seat belt pre-tensioner in order to reduce their response time and match their output to the severity of the crash." Mercedes has a similar system on the S-Class called "Pre-Safe" that pre-tensions the seatbelts, adjusts the seats to their optimal crash position if necessary, and closes the sunroof should the vehicle skid. However, Lyons says coordinating these functions with an active safety system improves response time further, and increases the vehicle’s ability to respond properly to accident scenarios. Bosch expects automakers will add CAPS to high-end luxury models starting with the 2009 model year.—CAS