Automotive Technology – Active and Passive Safety Systems
A driver is desperately trying to make a business appointment and fiddles with the phone to call ahead that she is running late. Another flips through a portfolio of CDs trying to find just the right music selection. Both overestimate their abilities and swerve momentarily into the next lane.
In today’s busy world, people often find themselves multi-tasking; and unfortunately, drivers are taking this trend to the road. According to the National Highway Traffic Safety Administration (NHTSA), not only do the majority of Americans view driving as a routine task (i.e., not worthy of special attention), 50% of all crashes involve driver “inattention.”
Safercar.gov agrees. It says 90% of vehicles in “fatal, single-vehicle rollovers involved routine driving maneuvers” and 85% of “rollover-related fatalities are single-vehicle crashes.” Based on these statistics, driver behavior seems to play a crucial role in fatal rollover crashes.
At the same time that drivers are being implored to practice safe and attentive driving, automotive engineers are also eager to create new technologies to help increase roadway safety. Isn’t there some fancy device that could warn a driver when he drifts into the next lane? React when another vehicle is in his blind spot? Apply the brakes before a crash?
Pre-crash mitigation systems attempt to combat some of the common causes of automobile accidents through warnings and automatic adjustments. Such systems are the focus of research initiatives into roadway safety and include adaptive cruise control, forward collision warning, lane departure warning and side alert systems.
In a forward collision warning system, the vehicle’s system literally senses the distance between it and the vehicle or object ahead of it in the lane. Predicting the possibility of an accident by sensing the distance between slower moving and stopped vehicles ahead, it warns the driver when appropriate. If a crash occurs, the system initializes precautionary measures – such as pretensioning motorized safety belts and applying brakes. Indeed, active braking in the seconds before a collision can play a major role in crash energy reduction.
According to NHTSA, some 200,000 accidents every year are due to lane changes. To help reduce the number of these accidents, lane departure warning systems have been designed. They caution drivers when their vehicles leave their intended lanes. Using a monocular camera mounted behind the windshield, the lane departure warning system’s software programs estimate lane width and road curvature, determine the vehicle’s heading and lateral position and initialize a tactile, visual or audible alert to its driver when he or she crosses a line.
It’s not difficult to guess, then, what side alert systems do. Using infrared sensing and other technologies, such systems help drivers become aware of vehicles in side blind spots. In some models, these sensors are integrated into mirrors, taillights and side fascia. The side blind spot region is scanned for temperature changes to detect a vehicle, a visual indication can be given in mirrors, and, when necessary, an audible alert can be issued. The technology is so advanced, sensors ignore stationary roadside objects and are immune to noise.