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 at least one electromagnetic wave towards the ground, receiving at least one reflected electromagnetic wave (M') from the ground and transmitting a signal representing said at least one reflected electromagnetic wave (M') to the command and control unit; the lawn mower robot being characterized in that the command and control unit comprises at least one classification module, which determines the presence of grass in the area of ground along the working trajectory in the feed direction as a function of a representative signal of the at least one reflected electromagnetic wave (M'); said classification module comprises a module for sampling the reflected electromagnetic wave (M'), configured for deriving a finite number of samples from the at least one reflected electromagnetic wave (M'), the classification module being configured to determine the presence of grass in the area of ground along the working trajectory in the feed direction as a function at least of the finite number of samples of the at least one reflected electromagnetic wave (M') transmitted by the radar sensor, wherein the radar sensor is configured to emit a plurality of electromagnetic waves separated temporally by intervals of between 0.1 ms and 10 ms. - 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 at least one electromagnetic wave towards the ground, receiving at least one reflected electromagnetic wave (M') from the ground and transmitting a signal representing said at least one reflected electromagnetic wave (M') to the command and control unit; the lawn mower robot being characterized in that the command and control unit comprises at least one classification module, which determines the presence of grass in the area of ground along the working trajectory in the feed direction as a function of a representative signal of the at least one reflected electromagnetic wave (M'); said classification module comprises a module for sampling the reflected electromagnetic wave (M'), configured for deriving a finite number of samples from the at least one reflected electromagnetic wave (M'), the classification module being configured to determine the presence of grass in the area of ground along the working trajectory in the feed direction as a function at least of the finite number of samples of the at least one reflected electromagnetic wave (M') transmitted by the radar sensor, wherein the radar sensor is configured to emit a plurality of electromagnetic waves separated temporally by intervals of between 0.1 ms and 10 ms.