Keyestudio Micro:bit Mini Smart Robot Car V2 Instructions Manual page 86

That is why the micro:bit car can automatically follow the black track, achieving the automatic line tracking
function.
Programming Thinking
Set the KEYES-2812-18R module to turn on 18 RGB LEDs in various colors.
1
Judge white and black line by both side line tracking sensors.
2
If right side tracking sensor detects black line, robot turns right; if left side tracking sensor detects black
3
line, turn left; if both side sensors don't detect black line, stop; if both side sensors detect black line, go forward.
Source Code
60