Robot wants to stay on the center line (setpoint).
Obstacles appear on the line and move toward you.
Use Up/Down or ↑ / ↓ to dodge obstacles.
When you leave the line, the tracking error grows and the
graph below shows it.
Time: 0.00 s
Normalized error: 0.00
Hits: 0
Teaching idea: setpoint = center line.
Error = distance from line.
Students see that disturbances/obstacles force them to move,
and the error graph spikes whenever tracking is poor.