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ABCs of Car Tech: Driver aid systems

In this week's edition, CNET takes a look at the advanced car tech systems that help prevent accidents and make driving more convenient.

Antuan Goodwin Reviews Editor / Cars
Antuan Goodwin gained his automotive knowledge the old fashioned way, by turning wrenches in a driveway and picking up speeding tickets. From drivetrain tech and electrification to car audio installs and cabin tech, if it's on wheels, Antuan is knowledgeable.
Expertise Reviewing cars and car technology since 2008 focusing on electrification, driver assistance and infotainment Credentials
  • North American Car, Truck and SUV of the Year (NACTOY) Awards Juror
Antuan Goodwin
6 min read
BMW 550i
David Freeman/CNET

Last time, we took a look at how cars protect their passengers in the event of a crash. This week, we're taking a look at a few high-tech ways that modern vehicles can help prevent accidents in the first place.

Modern tech cars can be equipped with a host of driver aid systems that help make driving easier for your average commuter. From road-aware cruise control systems to self-aware headlight systems, cars are getting smarter every day.

Adaptive cruise control
If the standard cruise control system was the first step toward vehicular autonomy, then adaptive cruise control system is the giant leap, so to speak.

Just as with standard cruise control, users can preset the adaptive system's speed and the vehicle will attempt to maintain its velocity. However, adaptive cruise control uses forward-facing sensors (either laser- or radar-based) that allow it to "see" the road ahead, monitoring for other vehicles. In the event that a vehicle is detected, the system will match the speed of the car ahead and maintain a safe driving distance. For example, you approach a 50 mph vehicle while doing 65. The adaptive cruise control will match the 50 mph rate at a reasonable following distance until the road ahead clears up. At which point, it will resume your preset cruising speed of 65 mph. It does all of this with no intervention by you, the driver.

Volvo's City Safety system helps prevent crashes by braking for the driver in the event of imminent collision. Volvo

Collision mitigation system
The same forward-facing sensors that allow adaptive cruise control to do its thing can be repurposed to keep an extra digital eye on the road even when you're not cruising. Collision mitigation systems (sometimes also called collision avoidance systems or precollision sensors) can watch for rapidly closing distances between your vehicle's front end and a potential obstruction--which is usually a dead giveaway that you're about to hit something.

What these systems do next varies wildly from application to application. Some systems simply pre-tense the seatbelts and flash warning lights in a sort of last-ditch effort to grab the attention of the driver before impact. More sophisticated systems can prime the brakes (shaving fractions of a second off of stopping time) or even brake for the driver, applying full braking force before you have time to react. Some systems, such as Volvo's City Safety system, can even bring the vehicle to a complete stop if triggered below a certain closing speed. The very best systems eschew lasers and radar for camera-based detection methods that can discern pedestrians, cyclists, and animals.

Proximity detection system
Unlike the longish-range radar or laser systems, short-range proximity detection systems usually use sonar to judge the distance between your vehicle's bumper and a potential obstruction. These systems are most commonly found at the rear end of a car, activating only when reversing and notifying the driver of an impending collision with an increasingly plaintive beeping. However, some of these systems include 360-degree coverage and, in the case of BMW vehicles, a sort of graphic representation of the areas directly ahead of and behind the vehicle.

Ford's blind-spot warning technology, lifted from Volvo, shows a warning light in the side-view mirror when there is a car in the blind spot. Corinne Schulze/CNET

Blind-spot monitoring
The same type of sensors that comprise the proximity detection hardware are often found as part of a blind-spot monitoring system. Only, instead of watching for bumpers and errant motor scooters while parallel parking, blind-spot monitors look for obstructions in your vehicle's blind spots--those pesky wedge-shaped areas near the rear of the car (at about 5 and 7 o'clock) that can be difficult to view with improperly adjusted mirrors.

When activating the turn signal for a lane change, if the vehicle detects an obstruction in the corresponding blind spot, then it will sound an audible alarm and/or illuminate some sort of indicator (often in or near one of the side wing mirrors). Many of these systems only work above a certain speed, but Ford's BLIS with Cross Traffic Alert works at parking-lot speeds and can even alert the driver to vehicles approaching from the left or right (cross traffic) while you're reversing out of a tight spot.

Rearview camera system
Hearing about what's happening behind your car via a series of bleeps and bloops is good. However, for most, direct visual feedback is probably best and safest. A rearview camera system is pretty self-explanatory. It's a small camera located at the back of the vehicle that lets you look behind your car using a monitor. Many of these systems simply repurpose the 6- to 8-inch screen used for infotainment and navigation to display the rear view, but for space-saving purposes, some use small 2.5- to 3-inch monitors embedded in the traditional rearview mirror.

Camera systems greatly aid in parking, preventing accidental collisions with curbs, other cars, and--most importantly--pedestrians and small children. CNET

The very best of these systems utilize what are called trajectory marks--a graphic overlay of the predicted path of the vehicle that updates with the rotation of the steering wheel.

In addition to rearview camera systems, there are also side-view camera systems, often located at the front end of long-nosed luxury vehicles, that give drivers a peek around corners when inching out of driveways and alleys with limited cross traffic visibility. There are also systems such as Infiniti's around-view camera system that stitch together front, side, and back camera views into one 360-degree view of the vehicle's (often an SUV or crossover) perimeter.

Lane-monitoring system, lane-keep assistance
Using forward-looking cameras, a lane-monitoring system tracks the vehicle's position between the painted lines marking the lane boundaries. When it detects that the car is crossing one of these paint lines without activating the turn signal, the driver will be alerted. Sometimes it's as simple as an audible chime and sometimes it's a slight vibrating of the steering wheel.

Lane-keep assistance systems will try to pull the vehicle back into its current lane if the driver fails to intervene while drifting across the lane marker line or fails to use the turn signal. Sometimes this is accomplished by bias braking--activating the brakes on one side of the steering axle to pull the nose of the vehicle in the right direction. Systems with electronic power steering can use the computer-controlled steering rack to make small corrections to vehicle's path. In either of these cases, the driver can override the intervention simply continuing to turn the wheel in the desired direction.

Active steering headlights
Simply put, active headlight systems feature small built-in motors that adjust the direction in which light is cast relative to the direction that the vehicle is moving. Crank the steering wheel to the right and the headlights steer with the wheels, effectively bending the light around the corner that the car is currently rounding and putting the available illumination where it's needed the most. Active headlights are usually projector-type high-intensity discharge (HID) lights, as this type of lighting system's accurate beam is the most directionally sensitive and the smaller projector housing is easier to aim than a large halogen reflector. Note that this is a different technology from the auto-leveling feature that many HID lighting systems have, although the two are not necessarily mutually exclusive.

Modern headlamps are no longer just static lights and are capable of being steered and activated automatically. CNET

Active high beams
Dig around the Internet for it and you may come across statistics published by the U.S. Department of Transportation indicating that drivers use their high beams less than 25 percent of time when conditions would justify their use. Whether it's because we forget the high beams are there, fear dazzling oncoming drivers, or just don't want to be bothered with constantly switching them on and off in moderate rural traffic, most of us almost never reach for the high beam switch.

Here's where active high beams come into play. By utilizing a forward-facing camera that watches for the telltale glow of headlamps or taillights, an active high beam system is able to deactivate your brighter lights when approaching other drivers and automatically reactivate them when the road ahead is clear. This gives drivers the benefit of increased forward vision at night with the added convenience of automation, making the road safer for you and those around you.

That's it for this driver-aid tech roundup and this week's edition of the ABCs of Car Tech. If you have an element of car technology that's got you scratching your head, sound off in the comments or shoot us an e-mail and we'll break it down for you in a future edition.