How do self-driving cars work?

Autonomous vehicles combine several sensors. Cameras read signs, lights and lane markings; radar measures the speed and distance of other vehicles; and lidar fires laser pulses to build a detailed 3D map of the surroundings. Software fuses this data to detect objects, predict how pedestrians and drivers will move, and plan steering, braking and acceleration many times a second, often helped by highly detailed maps. Engineers describe automation using six SAE levels, from 0 (no automation) to 5 (full automation anywhere). Waymo launched fully driverless public robotaxi rides in Phoenix in 2020 and has since expanded to other US cities.