Abstract: Robot system including at least one mobile robot (10), for treating a surface, which comprises map storage means to store a map of the surface to be treated and means to navigate the, or each, mobile robot (10) to at least one point on a surface. The, or each, mobile robot (10) comprises locating means (13,14) to identify its position with respect to the surface to be treated and means to automatically deviate the mobile robot (10) away from its initial path in the event that an obstacle is detected along its path. The, or each, mobile robot (10) also comprises means to store and/or communicate data concerning the surface treatment performed and any obstacles detected by the locating means (13,14).