The hardest part, however, is for the robot to estimate and maintain the accurate true “North” heading. There is gyro drift, wheels’ slippage, and other sources of estimation errors…
We tried to do this for NbN. For debugging purposes and to let drivers know what robot thinks of its current heading there was a motor mounted on top of the robot with a giant cardboard arrow to indicate the heading. Then drivers could turn their own body to align with arrow or use special controller keys to adjust the robot’s heading estimate.
As you can imagine this wasn’t something that makes drivers’ life easier. It was more confusing than helpful and cost extra motor. So it was scrapped after less than a week of testing.
In any case, here is some useful related information: