Darkness and Fog Sensor for Car Safety
The German Franhoufer institute has unveiled a new device designed to not just calculate light levels, but determine the type of darkness a car is driving through. Intelligently determine whether the car has just driven into a tunnel, has driven through smoke, entered a fogbank, or simply waning light levels due to the onset of dusk.
It affixes to the winsdshield, just in front of the rear-view mirror, and its three sensors face forwards, out into the road ahead. Designed to be networked, it operates as one of preferably many sensors designed to aid the driver's experience, or as sensors to aid driverless cars and road safety.
Over the past few years, German traffic fatalities have fallen thanks to these types of sensors. Numerous new driver-assistance systems that react more quickly than a human being can. They identify risks, warn of hazards and assist the driver in critical situations. Radar sensors, for instance, scan surrounding traffic conditions, monitoring the vehicles blind spot or maintaining a safe distance to the vehicle in front; infrared detectors improve night vision, and fatigue sensors sound an alarm if there is a risk of momentary driver drowsiness.
However, as always, the one overriding issue with these types of hardware interface system is cost. The cost of developing and deploying such systems is often too high to ensure overarching coverage, with such systems typically being limited to higher-end vehicles, and the rest just left to fend for themselves as best as pure human senses can.
This is hardly an ideal situation, and one which many parties would like to see changed. Cheap, efficient sensor systems could be rolled out to all vehicles, not just in Germany,. But across Europe. They would not impinge on the price of the car, but would bring the benefits of faster reaction times, and smart cars able to react to changing conditions, to all road users.
This sensor has thus been developed with that in mind. Part of the EU-sponsored ADOSE project, researchers at the Fraunhofer Institute for Reliability and Microintegration IZM in Berlin, working with Centro Ricerche Fiat and the chip manufacturer STMicroelectronics, have developed a sensor system that can be inexpensively produced for all road vehicles. It's not perfect, but it is a start.
The system consists of an entire camera, two sensors equipped with Fresnel lenses to detect light signals, and an infrared LED. Between the three, even conditions which offer the same basic light levels, such as thick fog and night driving can be differentiated.
It does this by allowing a wide-angle camera picture, without a wide-angle lens. Instead, a cheap lens can be used, but a procedure known as hot stamping lightpipes allows lioght to enter from all around the lens. They are basically hollow, mirrored tubes that can deflect a light signal by as much as 90 degrees. Up until now, optical fibers have been used to transmit these signals. But these snap at even low bending radii, are expensive and must be painstakingly mounted in place manually. The lightpipes can just be cast in place by machine. If a few break, it doesn't matter sheer numbers get the job done.
A prototype of the sensor module is already being tested. Centro Ricerche Fiat is currently putting it through the paces in an initial field test.