Car tech: Taking drivers' helpers for a spin

Think your spouse is a back-seat driver? Check out some of these automated features.

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On the Acura ZDX, the blind-spot sensors use two 24GHz radars to transmit a short radio blip and then listen -- using multiple antennas on the car -- for a return blip. If the car calculates that the return blip is from another vehicle within a set distance, the car will show the blind-spot warning in the side mirrors.

During my test drive with the Buick Lucerne, the blind-spot indicators were exceptionally precise: Any approaching vehicle would immediately set off an alert in the side mirror. On the other hand, embankments, railings or buildings did not cause a warning.

Collision detection

Several models come equipped with a collision detection and prevention system. For example, the Audi A8 will not only brake slightly if the car senses another car ahead, but will apply brakes in full force if impact is imminent. O'Reilly says these braking systems use an accelerometer -- not that different from the one in the Apple iPhone -- that senses a rapid change in the tilt of the accelerator. If you are driving normally and suddenly release the gas pedal, the car will boost the brakes with fluid for better braking.

Albert Austria, a senior evaluation engineer at car Web site Edmunds.com, says the most advanced collision-detection systems, such as those in Mercedes and Audi vehicles, use sensors to detect the tail lights of the car in front of you. The sensors know the difference between a truck and a tree but, he says, most collision-detection systems cannot identify a fully stopped car because the sensors scan for moving objects. Collision detection works similarly to blind spot and lane-departure warning systems.

"The sensors pick up the objects of interest and send the information to several of the vehicle's electronic control units (ECUs) which have many microprocessors," says Austria. "The ECUs have complex algorithms that calculate vehicle intervention and course of action based on many inputs" such as vehicle speed, throttle position, closing distance to object, brake application, yaw (side to side), roll (pivot along a straight line) and pitch (up and down).

On the Acura ZDX, the collision-detection system uses a millimeter-wave radio -- the highest radio-frequency band -- in the front grille, scanning about 300 feet ahead. Interestingly, this feature, called the collision mitigation braking system, uses responses from the driver to determine how to brake. It first tracks an obstruction in real-time, then alerts the driver visually and audibly, waits for a response, applies slight braking, displays more warnings, then applies full brakes and tightens seatbelts automatically.

Other automation

Some cars use technology to help control other features. One of the more recent models is the Mazda3 (the Grand Touring model with advanced technology package), which has headlights that turn automatically when you drive around a bend in the road instead of just pointing off into the darkness; a weight sensor that moves headlights if you load up the trunk so the headlights point in the right angle and direction; and rain-sensing windshield wipers so you don't even need to turn them on when it rains.

Multiple sensors on the Lucerne

These sensors on the back of the Buick Lucerne help with parking.

Click to see larger image

The headlights move by reading the location of the steering wheel, your speed and the pitch of the car on the road via an accelerometer. For adjusting the height of the headlights based on cargo load, the car uses an accelerometer on the right side of the vehicle that determines the current pitch and also takes current speed and the angle of the road (based on ride height) into account. For rain sensing, there is an infrared sensor that projects lights through the windshield. If obscured or diffracted in all directions (e.g., caused by rain water), the windshield wipers start working automatically.

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