A robotic mower navigation system includes a plurality of sensors on a robotic mower that detect strength and polarity of a magnetic field from an electric current through a boundary wire. An electronic control unit receives data concerning the magnetic field from the plurality of sensors as the robotic mower follows the boundary wire, tracks the data provided by the sensors, compares the data with a reference pattern that defines at least one specified feature of the boundary wire, and provides commands to the robotic mower based on the comparison. The electronic control unit may command the robotic mower to follow a second boundary wire to a remotely located charging station instead of the first boundary wire based on detected features of the boundary wire such as sharp corners or crossings.