A navigation system for a robotic mower includes a boundary wire defining a boundary of a specified area; a boundary sensor assembly, and a vehicle control unit with a navigation arbitration logic configured to arbitrate a selection between at least a straight propagation mode and an arc propagation mode. The navigation arbitration module is configured to select the arc propagation mode when the sensor assembly indicates that the mower approaches the boundary of the specified area and has a distance from the boundary that is equal to or smaller than a specified turn distance. The boundary sensor assembly generates a sensor signal representative of a measured yaw angle of the mower relative to the boundary wire, and the navigation arbitration logic is configured to generate output information representative of a desired yaw angle dependent on an assumed actual yaw angle.