Autonomous lawn mower using perimeter cable with electrical signal

An apparatus for cutting grass comprising:

• a lawn mower equipped with:
• movement means for movement of said lawn mower at least inside a cutting area (S);
• one or more blades for cutting grass in said cutting area (S);
• a perimeter cable, delimiting said cutting area (S);
• a management device for generating an electrical signal (ES) and for propagating the latter in said cable;
• and
• a recharging base for said lawn mower positioned along said perimeter cable;
• wherein said lawn mower further comprises a control unit equipped with:
• sensor means for detecting said electrical signal (ES) and for detecting, while said lawn mower is in operation, a maximum value (Vmax) and a minimum value (Vmin) for an intensity of said electrical signal (ES) being detected;
• wherein said maximum value (Vmax) and minimum value (Vmin) relate to the intensity of the electrical signal (ES) detected by the sensor means;
• a memory for storing said maximum value (Vmax) and said minimum value (Vmin) for an intensity of detection of said electrical signal (ES), said maximum and minimum values (Vmax, Vmin) being respectively representative of a minimum distance (Dmin) and a maximum distance (Dmax) of said lawn mower from said perimeter cable;
• a calculation module configured to determine, for said intensity of detection, a target value (Tv) that is non-null and comprised between said maximum value (Vmax) and said minimum value (Vmin), said target value (Tv) being representative of a target distance (Td) of said lawn mower with respect to said perimeter cable, said target value (Tv) being substantially different from a preceding target value determined for said intensity of detection;
• and
• an operative module including a comparison module, wherein said operative module is configured for combining the information coming from the sensor means and from the calculation module;
• wherein said comparison module is configured to compare the target value (Tv), obtained by said calculation module, with the intensity of the electrical signal (ES) being detected by the sensor means;
• wherein said operative module is configured for sending appropriate command signals to the movement means so that, during movement of the lawn mower, the intensity of the electrical signal (ES) detected by the sensor means is substantially equal to the target value (Tv), keeping said lawn mower at a distance, with respect to said perimeter cable, that is substantially equal to said target distance (Td) during movement of said lawn mower towards said recharging base.