Method and apparatus for calibration of a robot positioned on a movable platform

A method for determining the placement of a real robot including a plurality of joints and positioned on a movable real platform, in relation to a real work object, using a real measuring unit mounted on a wrist of the real robot, the method including first steps performed by a processor coupled to a memory including a software CAD system, which first steps comprise:

• loading CAD models of the real robot, the real movable platform, the real measuring unit on the real robot, and the real work object into the CAD system;
• placing the CAD platform and the CAD work object in a relation to each other so that the CAD robot is able to reach the CAD work object;
• manipulating the joints of the CAD robot until the CAD measuring unit is moved to a first position and orientation in relation to the CAD platform allowing measurement of a CAD first feature of the CAD work object;
• storing the first position and orientation of the CAD measuring unit;
• generating a first CAD model of the CAD first feature based on the CAD work object as seen from the CAD measuring unit in the first position and orientation and;
• storing the first CAD model of the CAD first feature in the CAD system;
• and the processor performing second steps on the real robot:
• automatically moving the real robot to achieve the first position and orientation of the real measuring unit in relation to the real platform;
• moving the real platform to a place where measurements of the real first feature can be made;
• performing 3D measurements of the real first feature by the real measuring unit;
• generating a second CAD model of the real first feature based on the 3D measurements of the real first feature;
• performing a best fit, including scaling and rotation, between the first and the second CAD models of the first feature, and calculating a 6 degrees of freedom (DOF) pose difference between the first and second CAD models based on a result of the best fit;
• and
• adjusting a position and orientation of the real platform by instructing the real platform to move and reorient to compensate for the calculated pose difference.