Complementary metal oxide semiconductor (CMOS) imagers are gaining popularity in vehicles as active-safety systems expand their roles. Now that they have proven their mettle in backup systems, cameras built upon those imagers are being used to look at all kinds of things in front of the vehicle.
“Forward-looking cameras can do more than lane-departure warning; they can provide automatic headlight control, and in Europe they’re looking at traffic-sign recognition,” said John Prainito, Chief Engineer for Camera Development at TRW. “They can also track the vehicle in front of you and do short-range pedestrian detection.”
Another safety-related role is to augment vision at night. Adding near-infrared lighting to headlight modules makes it possible to let cameras extend a driver’s field of vision without blinding oncoming drivers.
“Near infrared lighting isn’t visible to humans, but for CMOS imagers, it provides the same light intensity as high-beam headlights,” said Cliff De Locht, Optical Marketing Manager at Melexis Inc. “Near IR is being used by Mercedes for night vision, letting drivers see beyond the vision they have with headlights.”
In safety, one of the knocks on cameras has been their inability to see in fog and snow when drivers need them most. That is being alleviated by improved software that pulls more data from fewer bits. Faster microprocessors make it possible to compare data from each frame even when cameras are running at 30 frames per second, letting developers do more in software.
“Depending on algorithms, cameras can see in rain and fog when people can barely see a thing,” said Martin Duncan, Innovative Systems Manager at STMicroelectronics. “Algorithms can enhance images and extract data, comparing frame-to-frame and looking for things that move.”
The imagers themselves have also advanced so they can quickly adapt to changing conditions. Improved depth-of-field and wider focusing areas make it possible for a single imager to watch lane stripes, road signs, or several vehicles on a busy highway.
“On a normal day, we can track up to eight different vehicles, in your lane and other lanes, at distances up to 100 meters,” Prainito said. “Going in and out of dark tunnels on sunny days is not a problem. Imagers have higher dynamic ranges and there has been a lot of work in the algorithms.”
While improvements like these make cameras more useful in forward-looking applications, enhanced cameras are also extending their role in backup and parking systems. Some automakers use ultrasonic sensing in these applications. But camera makers say their technology can improve safety and even reduce parts count.
“We’ve got the ability to look close to the ground,” said Norm Torrey, Automotive Business Development for Canesta. “We can see a child crawling on the ground. Ultrasonic sensors get false detection from the ground. One camera can also pick out several things. It might require a few ultrasonic sensors to pinpoint multiple objects.”