Robot system and calibration method of the robot system

A calibration method of a robot system, wherein

• the robot system comprises:
• a robot body configured to operate a work;
• a visual sensor;
• and
• a control apparatus configured to control a position and an orientation of the robot body, and to calculate a position and an orientation of the work using a measured value by the visual sensor, wherein
• the calibration method is performed for a calibration between a robot coordinate system fixed to the robot body and a vision coordinate system fixed to the visual sensor, and
• the calibration method comprises
• operating, by the control apparatus, the robot body to obtain three teaching points within a calibration area;
• and
• observing a marker by the visual sensor, to calculate a calibration value based on a position of the robot body in the robot coordinate system, and a position of the marker in the vision coordinate system for at least the three teaching points, wherein
• two of the three teaching points are placed on different positions in a plane A of a finite size normal to an optical axis of the visual sensor, wherein the marker at two of the three teaching points has the same inclination in relation to the optical axis of the visual sensor, and wherein the marker at the teaching point other than the two of the three teaching points has an inclination different from that of the two of the three teaching points and crosses the plane A.