It is described a working apparatus for a limited working area, comprising a base station configured to generate a magnetic field and a self-propelling robot. The self-propelling robot comprises means for moving the self-propelling robot in the working area, a gyroscope, a magnetic field sensor and a processing unit configured to control the movement of the self-propelling robot. The processing unit comprises a magnetic field search module configured to move the self-propelling robot so as to search for the set of contiguous magnetic field lines of force inside the working area according to a defined search path, and comprises a magnetic field tracking module configured to move the self-propelling robot to track at least a portion of the set of found contiguous lines of force by means of a plurality of maneuvers of crossing the set of found contiguous lines of force until reaching the base station.