|How MIT's car sees the world with a LiDar sensor (MIT illustration)|
Though self-driving cars rely on detailed maps to help them figure out where they are in a city, many have a LiDAR (Light Detection and Ranging) sensor that helps it see curbs and other obstacles. The MIT team juiced up their test vehicle's LiDar sensor to help it detect the difference between the asphalt and the grass. The LiDAR's 64 lasers each spun around 10 times per second, providing constant feedback on what the car's surroundings look like and where it was on the road.
That’s how the car perceived where the road was in front of it, but it still had to know how to drive to its destination without a great 3D map in its silicon brain (although it did have GPS)," Verger reports. "To do that, it picked a 'local goal'—a point in the road up ahead that the car could see, and drove towards it. But it didn’t just drive to that point and stop. The vehicle constantly refreshed that goal as it approached it, like paddling towards a point on the horizon on a big, flat lake."