The invention relates to a system for processing a ground at least partially in an outdoor region, in particular removing dirt or grass cuttings, comprising a base station (6) and a mobile robot unit (8). The technical problem of improving the operating results of a mobile robot unit while simultaneously improving operating safety, is solved in that at least one detection means (24) for detecting at least one environmental variable is provided, and in that a controller (34) is provided which influences the operating mode of the mobile robot unit (8) in accordance with the value of at least one of the environmental variables detected by the at least one detection means (24). The invention further relates to a method for controlling a mobile robot unit for processing a ground at least partially in an outdoor region, in particular removing dirt or grass cuttings.
