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Lane Departure Warning System

The automobile industry is constantly introducing innovative technology, usually first on luxury vehicles. Some technologies like anti-lock braking, all-wheel drive, on-board navigation, and electronic stability control are examples of those that catch on and soon are available throughout the industry. Then, there is gee-whiz technology like night vision systems, four-wheel steering and head-up-displays that turned out to be pretty much duds. It will be interesting to see where the Lane Departure Warning (LDW) system recently introduced by Nissan’s Infiniti division will wind up. LDW is being offered on the 2005 FX crossover SUV and the 2006 M45 performance luxury sedan.

A 2003 study by the National Highway Transportation Safety Administration concluded that 55-percent of fatal accidents were the result of a vehicle leaving its lane and colliding with another vehicle or a roadside obstacle. Nissan, working with Valeo SA and Iteris, developed the LDW system to warn drivers when their Infiniti veers out of its designated traffic lane. Iteris has already developed LDW systems for over-the-roadtrucks.

Infiniti’s LDW system uses a small camera mounted behind the rearview mirror to detect the lane marking on the road. A speed sensor measure vehicle speed. The camera’s image and vehicle speed are sent to the system’s micropocessor where this information is used to calculate both the distance between the vehicle and the lane markings and the rate of change of the lateral velocity relative to the lane marking. The microprocessor then compares this to its programming to determine if the vehicle is moving out of its lane. If from the distance and lateral velocity, it is determined that the vehicle is moving out of the lane the driver is alerted by indicator light on the instrument panel and by a buzzer-like warning.

The system will not work if the camera can't detect lane markers or if vehicle's speed is below 45 mph. The driver can turn off the system temporarily via a manual switch, but is automated activated again when the vehicle is restarted. Also, the system doesn’t provide a warning when the appropriate turn signal is used indicating an intended lanechange. LDW is one way to get drivers to use their turn signal.