January 2, 2008

Exterior vehicle sensors

By Jim Kerr

Electronic controls need sensors to be able to determine what is happening with the vehicle. Engine computers monitor oxygen sensors to adjust fuel mixtures, antilock brake systems monitor wheel speed sensors to calculate wheel slippage, and airbag computers use crash sensors to sense an impact. All this is done in less time than it takes to blink.

Electronics are now allowing manufacturers to add more sensors to vehicles, many of which help the driver make better decisions about how they drive the vehicle.

Rear Object Detection was one of the first of these systems added to vehicles. It was just a decade ago when I drove a Ford Windstar with the sensors in the bumper. This system uses four sonar sensors on the back bumper to identify objects behind the van and a warning beeper to notify the driver if something is there. The usefulness of it quickly became apparent when I started to back out of a parking lot. The beeper went off but I could see nothing behind the van in the mirrors. I hadn't seen anything there when I entered the van so I thought the system must be sending a false alarm, but to confirm this, I walked around the back of the van. There sat a little bush bunny, cowering in fear. It could have as easily been a small child, and the system did warn me.

Since that time, I have used Rear Object Detection systems on vehicles from many manufacturers. The closer the vehicle is to an object, the faster the warning beeps sound. Some systems include amber and red warning lights too, so you get a visual indication of how close an object is. In my experience, when the beep becomes a solid tone, you are about 150 to 300 mm away from an object. These systems are worth every penny when trying to back into a tight parking spot, or if it prevents backing over that bicycle. Some vehicles, such as Lexus and Porsche offer front object detection too, which makes parking much easier.

Back-up cameras are now offered on many vehicles too. I first used these in large motorhomes, where rear visibility was extremely limited. Now, some SUV's, pickups and passenger cars are using cameras. It used to be you had to have an expensive video screen on the dash so you could see the camera image of the area behind the vehicle. Now, Toyota offers an option with a smaller display as part of the driver information centre, and Ford is displaying the camera view in the rear-view mirror as a feature on some 2008 trucks and SUV's. I like the Ford system. The mirror looks normal until the vehicle is placed in reverse. Then a portion of the mirror suddenly becomes a video display, showing both the vehicle's rear bumper and the area around it. When combined with the sonar-based Object Detection systems, there is no longer any possible excuse for backing into something.

Some systems, such as the Lexus and Infiniti displays also show lines on the screen where the vehicle will be when it is backing up. Turn the steering wheel and the display lines also move to indicate the new vehicle position. The newest Infiniti model, the Infiniti EX utility vehicle, takes exterior views one step further by incorporating cameras at the bottom of each side mirror and the front of the vehicle as well. The driver can see how close the side of the vehicle is to a curb or rock (when off-road) or they can push a button and see a computer-generated "bird's eye" view of the complete area around the vehicle.

Cameras on vehicles may sound like an expensive luxury, but there are aftermarket systems available too. The camera is mounted on the license plate - it's not much bigger than a walnut, and it is connected with three wires to power, ground and the back up lights. When the backup lights come on, the camera is powered up and sends a wireless signal to a small display that can be mounted in the interior. A friend of mine loves his, as it now allows him to back up accurately to the boat trailer the very first time. With a little imagination, I could see using this as a "baby cam" that allows a driver to quickly glance at infants in the rear seat, without having to turn around from the driver's seat and take their eyes off the road for extended periods of time.

Radar cruise systems, automatic parking systems and vehicle blind spot detection all use object detection and computer integration to warn drivers of potential hazards. At first, I thought they might be "toys", but now I see them as truly useful automotive features.

Jim Kerr is a master automotive mechanic and teaches automotive technology. He has been writing automotive articles for fifteen years for newspapers and magazines in Canada and the United States, and is a member of the Automotive Journalist's Association of Canada (AJAC).

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