A system (100) for cutting grass according to the invention comprises a lawn mower (1), a perimeter cable (2), delimiting a cutting area (A), in which a perimeter electrical signal (ES) is propagated, and at least one means (MSi； i= 1...n) for signalling a path change (”Pi； i= 1...n) associated with the perimeter cable (2), wherein the at least one means (MSi； i= 1...n) for signalling a path change (”Pi； i= 1...n) is configured to signal to the lawn mower (1) a path change (”Pi) relative to a predefined path (P PRED ) provided for by the predefined operation of the lawn mower (1), wherein the path change (”Pi) is signalled to the lawn mower (1) by means of an encoded signal (Si； i= 1...n) generated by the signalling means (MSi； i= 1...n), and wherein the lawn mower (1) comprises a sensor means (40) configured to sense the encoded signal (Si) and a processing unit (60) configured to actuate the lawn mower (1) as a function of the sensed encoded signal (Si) in order to cause the lawn mower (1) to make the corresponding path change (”Pi).
