Robot calibration system and method for calibrating the position of a robot relative to a workplace

A method for calibrating the position and orientation of a robot (1) with respect to a predefined plane (6) and point of reference (8) of a workplace (26) is disclosed. The method comprises the step of providing the robot (1) with a camera (4) having a camera center (34), The method comprises the following steps: - positioning the camera (4) in a first position (I), in which the camera (4) faces a mirror tag (10) comprising a reflective zone (12), wherein the reflective zone (12) of the mirror tag (10) has a planar surface (22) extending along a first plane (24); - moving the camera (4) until the first plane (24) of the mirror tag (10) is perpendicular to the center axis (30) of the camera (4).