An industrial robot system has at least one robot (1) having a robot coordinate system (xr1, yr1, zr1) and a positioner (2) having a positioner coordinate system (xp, yp, zp) and adapted to hold and change orientation of a workpiece by rotating about a rotational axis. Target points for the robot are programmed with respect to an object coordinate system (xo1, yo1, zo1). A robot controller (3), at least three calibration objects (24a-c) arranged on the positioner, and a calibration tool (26) held by the robot are provided. The positions of the calibration objects are determined for at least three different angles of the rotational axis of the positioner, to determine the direction of the rotational axis of the positioner and relation between the object coordinate system and the positioner coordinate system by performing a best fit between known and determined positions of the calibration objects.