The calibration index and taxonomy for robot kinematic calibration methods

The major approaches toward kinematic calibration are unified by considering an end-point measurement system as forming a joint and closing the kinematic loop. A calibration index is introduced, based on the mobility equation, that considers sensed and unsensed joints and single and multiple loops and expresses the surplus of measurements over degrees of freedom at each pose. Past work using open-loop calibration, closed-loop calibration, and screw axis measurement is classified according to this calibration index. Numerical issues are surveyed, including task variable scaling, parameter variable scaling, rank determination, pose selection, and input noise handling.