Industrial robot kinematic calibration using virtual line-based sphere surface constraint approach

Kinematic calibration is one of the most important methods to improve the positioning accuracy of industrial robots. This paper presents an efficient method to calibrate robots kinematic parameters. The proposed method is based on a laser pointer attached on the end-effector and a position sensitive device(PSD) located in the work space of the robot arbitrarily. In the process of robots kinematic calibration, the PSD rotates around a fixed point which keeps the surface of the PSD on the same sphere surface. In each position of the PSD, the laser beam is brought to the center of the PSD surface with various positions and orientation and the corresponding joint angles are recorded. Consequently, an optimization model was formulated and the Levenberg-Marquardt(LM) algorithm which used to solve the non-linear minimization problem was employed to identify the errors of the kinematic parameters. Simulations and experiments were performed and verified the feasibility of the proposed method.