The road is a hostile environment for software. Other drivers behave unpredictably. Pedestrians step out without warning. Rain, glare, and faded lane markings degrade sensor input. Autonomous vehicles must handle all of it in real time, with no room for a crash.

Perception combines cameras, radar, and lidar to build a model of the surroundings. Planning computes a safe path. Control executes steering, acceleration, and braking. Each layer depends on the others, and failures cascade quickly.

Levels of autonomy

1. Level 0, no automation
2. Level 1, driver assistance like adaptive cruise control
3. Level 2, partial automation with hands on wheel
4. Level 3, conditional automation with a fallback driver
5. Level 4, high automation in defined areas
6. Level 5, full automation everywhere

Deployment remains limited. Robotaxis operate in selected cities with safety drivers or remote monitoring. Full self-driving in arbitrary conditions is not available commercially, and the timeline keeps slipping.