Kinematic calibration of a re-configurable robot (RoboTwin)

This paper presents the calibration methodology developed for calibrating the RoboTwin (a re-configurable robot system). A steel bar of known length is used for calibrating the robot. The length of the bar is calculated using the nominal robot geometry and compared with the actual length to determine the error in the length. A method is developed to express the error in the bar length in terms of the kinematic parameters of the robot. This error is then minimized using a least squares algorithm iteratively to determine the real robot parameters. The calibration results are presented for a 3 DOF robot system.