While most automakers move toward implementation of camera systems for lane detection, BMW is bundling three vision features in a multifunction system. The BMW 7 Series uses technology from Continental and Mobileye N.V.
The single-camera system provides speed-limit information, high-beam assist (HBA), and lane-departure warning (LDW). Last year, BMW offered LDW on its 5 Series, and a handful of competing luxury-vehicle suppliers are also offering LDW.
Both systems were developed by Continental, though the 5 Series system was developed by Siemens VDO, which was acquired by Continental. Mobileye’s EyeQ chip, designed specifically for image processing, is used on both.
BMW’s headlight-detection system aims to let drivers benefit more from high beams, which are now often forgotten. It switches to low beams when oncoming headlights or taillights are detected.
The speed-limit function determines which road signs have speed-limit information and then displays them in the instrument cluster or the optional headup display.
Road-sign detection is a complex task because the signs vary from country to country and some signs are only for rainy conditions or for trucks. This complexity is increased in multifunction systems since cameras and image processors have to account for different parameters.
“For LDW, the ideal image is on the lower part of the image; traffic signs care about the upper part; and HBA requires an emphasis on light sources that’s contrary to the other two,” said Mobileye Chairman Amnon Shashua.
The system solves this by cranking up camera speeds, tripling the normal 15 frames per second rate. However, running at 45 frames per second shortens the time the shutter is open, reducing the amount of available light.
“We handle that with algorithms that let us handle inputs relatively quickly,” Shashua said.
Those algorithms run on a parallel processor that has two ARM 9 CPUs, six DSP (digital signal processor) cores, and 0.5 MB of memory. Another feature that makes the chip attractive is its low power consumption—roughly 2 W. By comparison, Pentiums consume around 100 W, Shashua noted.
Camera-based systems are expected to see significant growth in coming years as active safety gets more attention. General Motors and Volvo are also shipping vehicles that use Mobileye’s image processors.