One of the supposed serious problems with the use of lidar on autonomous vehicles is navigating in rain and snow. In fact, I remember one article recently that claimed this will significantly delay the widespread use of driverless vehicles.
I have good news. Ford seems to have solved the problem by using an algorithm that can resolve the difference between bad weather and a solid object.
The article states, “When a laser goes through the rain or snow, part of it will hit a raindrop or snowflake, and the other part will likely be diverted towards the ground. The algorithm, by listening to the echoes from the diverted lasers, builds up a picture of the “ground plane” as a result, said Jim McBride, technical leader for autonomous vehicles at Ford.”
“If you record not just the first thing your laser hits, but subsequent things, including the last thing, you can reconstruct a whole ground plane behind what you’re seeing, and you can infer that a snowflake is a snowflake,” he told Quartz.
Additionally, the algorithm checks for the persistence of a particular obstacle. A laser beam is unlikely to hit a raindrop twice, for example, allowing the algorithm to rule it out as an obstacle, McBride told Quartz.
McBride said Ford’s cars have driven through several millimeters of rain on the road. He wouldn’t say what depth of snow the cars have successfully navigated. Ford’s rivals in the driverless car race are also working hard on winter driving. Google is reportedly testing cars in Washington state, while Volvo is doing so in Sweden.