Described is a lawn mower robot comprising:

a frame;
cutting means configured for cutting grass, adjusting the height;
movement means, associated with the frame for moving it along a working trajectory in a feed direction;
a system for detecting the presence of grass in an area of ground along the working trajectory in the feed direction;
a computerised command and control unit operatively associated with said cutting means, movement means and detection system;
said detection system comprises a radar sensor configured for sending an electromagnetic wave towards the ground, receiving a reflected electromagnetic wave from the ground and transmitting a signal representing said reflected electromagnetic wave to the command and control unit.