A robot lawnmower (10) includes a robot body (100), a drive system (400), a localizing system (550), a teach monitor (600), and a controller (150) 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 (152a) and non-transitory memory (152b) in communication with the data processing device. The data processing device executes a teach routine (155) when the controller is in a teach mode for tracing a confinement perimeter (21) around the lawn (20) as a human operator pilots the robot lawnmower, 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.
