While some people contend that humans are the problem with autonomous cars, critics continue to point to situations in which they insist a computer could never handle chaos of driving as well as a human.
One of the situations that is frequently mentioned–even in the comments here at ECN–is snow. After all, for those of us in the north east, a driverless car that can’t operate safely in snow is basically useless for five months per year. (Editor’s Note: Nobody ever notes that human drivers are awful in the snow, but that’s another discussion entirely.)
While Google’s driverless cars are patrolling the snowless streets of California, Ford has taken on a bigger challenge with their driverless Ford Fusion Hybrid.
First the car uses LiDAR to create high-res 3D digital maps of the road and infrastructure, including signs, buildings, and trees. The car uses four LiDAR scanners generating 2.8 million laser points per second to create this map and in the process collects up to 600 gigabytes of data per hour. This is all done in ideal weather. For example, it might create a map of your commute during the summer, so in the winter it can use that map as a baseline to locate itself, even if the road is completely snow covered. According to Ford, their technology can locate exactly where the car is within a centimeter.
One concern people have with autonomous cars in the snow, is that the car will be confused by the precipitation. These sensors are designed to recognize snow and rain, and know that it is okay to drive through them as opposed to stopping the car (which it would do for a large object). When the sensors see snow or rain, they filter it out of the car’s “vision”.
The next concern is always what happens when snow, salt, ice or all three block a sensor. Because they sensors work as a team, combining all the data via sensor fusion, one faulty or blocked sensor won’t render the entire system unusable. All the sensors are monitored, so the car will know if something isn’t working right. In future versions, Ford is hoping that the sensors will be able to clean or de-fog themselves.
In case you’re already assuming that where ever they’re testing these cars isn’t harsh enough, they’re testing their cars in Ann Arbor, Michigan where they average 57.3 inches of snow each year.