Machine Design

Wake up! System warns drifting drivers

A lane-departure warning (LDW) system makes its debut on the Infiniti FX crossover sport-utility vehicle and alerts drivers of lane drifting.

It consists of a small camera, speed sensor, an indicator, and an audible warning buzzer.

The LDW system generates a warning to help alert the driver that the vehicle is about to move out of its lane. "Studies show that 55% of fatal accidents in the U.S. are from lane departure," says Robert Yakushi of Nissan North America Inc. "These are caused by various factors including driver distraction, inattention, or drowsiness," he adds.

Activating the turn signals temporarilydisables the LDW system. There is also a manual cancel switch, which lets the driver turn the system off. It resets itself when the vehicle restarts.

A small camera that mounts behind the rearview mirror takes note of lane markings. The camera's signal and vehicle speed go to a processing unit, which calculates the distance between the vehicle and lane markings as well as the lateral velocity to the lane marking. It then decides whether the vehicle is moving out of the lane depending on the distance and lateral velocity. It activates an indicator light on the instrument panel and a buzzer if conditions merit a warning. The system will not operate if the camera cannot detect the lane markers or if the vehicle is slower than 45 mph.

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