A robot lawnmower includes a robot body, a drive system, a localizing system, a teach monitor, and a controller in communication with one another. The drive system is configured to maneuver the robot lawnmower over a lawn. The teach monitor determines whether the robot lawnmower is in a teachable state. The controller includes a data processing device and non-transitory memory in communication with the data processing device. The data processing device executes a teach routine when the controller is in a teach mode for tracing a confinement perimeter around the lawn as a human operator pilots the robot lawn mower, when the robot lawnmower is in the teachable state, the teach routine stores global positions determined by the localizing system in the non-transitory memory, and when the robot lawnmower is in the unteachable state, the teach routine issues an indication of the unteachable state.