In normal driving conditions, the autonomous cars use multiple sensors, such as video cameras, GPS, laser (LiDAR), microwave or ultrasound. If the visibility is good, the problem has a complexity determined, but si has snowed, everything is much more difficult. Part of the signaling is blocked.
Ford is performing tests in environments that have snow, according to the manufacturer nobody has done this before. The tests are performed in the fictional town of Mcity (University of Michigan) and public roads of the area. Cars are Fusion (Mondeo in Europe) with autonomous system of the third generation.
The video cameras and sensors LiDAR are unable to see part of the road and the signage, both vertical and horizontal. So the car will know where you are going, you need a mapping three-dimensional with more detail than usual, since the GPS by itself does not allow enough precision in the normal maps.
Ford is based on a few maps more complex, developed with the University of Michigan, in which the car previously has taken note of where the buildings, signs, trees, etc, it Is have points of reference detectable when the conditions are adverse.
Thus, in the case of not being able to “see” the road, the sensors LiDAR will seek references on the map, in colloquial language, something that is familiar to you. Using points of reference and the GPS, the vehicle is able to determine its exact position, using the information previously gathered for orientation.
Ford is very concerned about the problem of the snow, given that 70% of the US population is concentrated in areas where it can snow throughout the year. The system that is being tested would not be effective using maps navigation conventional.
Ford has not specified how he was going to make those maps, but they could use a cloud-based solution. The cars that will circulate in good condition can make this mapping in real-time, and so re-transmit it to the vehicle when travelling through areas with bad weather.
Another function of the system is to determine to what extent they can keep driving safely, and for how long, to suggest a pause in the journey. The stability and traction control provide information that you have in mind for that purpose.
The Fusion Hybrid employees in the test are front wheel drive and do not use strings. The logic of driving must be adapted, because the have a lot less grip available, you should increase the distances to brake, maneuver more smoothly and run at a lower speed.