Method for limiting possible positions of a robot arm of a robot (1, 31), the robot arm comprising a base, a plurality of links arranged one behind the other and movable relative to each other with respect to axes (A1-A6), and drives for moving the links, wherein the robot (1, 31) is designed as a mobile robot comprising a mobile carrier device with drives for moving the carrier device, to which the robot arm is attached with its base and wherein the mobile carrier device is designed as a carrier vehicle with wheels and the drives of the mobile carrier device are arranged to move the wheels, comprising the following method steps: - Presetting a target position and target orientation in the space of a tool center point assigned to the robot arm or to an end effector attached to the robot arm, to which tool center point a reference coordinate system (K Ref) with polar coordinates (p1, p2) is assigned, - Assigning the potentially possible positions of the base of the robot arm in space and in the polar coordinates (p1, p2) of the reference coordinate system (K Ref) based on the geometry of the robot arm, in such a way that the tool center point is able to reach the specified target position and target orientation, - Determining the possible positions of the base of the robot arm based on the assigned potentially possible positions and on at least one constraint limiting the potentially possible positions of the base, wherein the constraint limiting the potentially possible positions of the base represents a possible position or orientation of the carrier device, characterized in that a 3-tuple (p1, p2, p3) describes the possible positions of the carrier vehicle by means of the polar coordinates (p1, p2) and by means of the rotation of the carrier vehicle in the reference coordinate system (K Ref), wherein the first polar coordinate (ρ1) of the reference coordinate system (K Ref) describes the distance of the carrier vehicle from the origin of the reference coordinate system (K Ref), the second polar coordinate of the reference coordinate system (K Ref) describes the approach direction of the carrier vehicle on a distance circle with the radius ρ1, and the rotation (ρ3) describes the orientation of the carrier vehicle with respect to the reference coordinate system (K Ref). - Presetting a target position and target orientation in the space of a tool center point assigned to the robot arm or to an end effector attached to the robot arm, to which tool center point a reference coordinate system (K Ref) with polar coordinates (p1, p2) is assigned, - Assigning the potentially possible positions of the base of the robot arm in space and in the polar coordinates (p1, p2) of the reference coordinate system (K Ref) based on the geometry of the robot arm, in such a way that the tool center point is able to reach the specified target position and target orientation, - Determining the possible positions of the base of the robot arm based on the assigned potentially possible positions and on at least one constraint limiting the potentially possible positions of the base, wherein the constraint limiting the potentially possible positions of the base represents a possible position or orientation of the carrier device, characterized in that