Abstract: In order to apply the three-dimensional surface scanning robotic system in manufacturing quality control, the robot positioning accuracy is the key element. A robot calibration method based on coordinates measurement machine (CMM) and nonlinear optimization is proposed. A measurement transition part which consists of three standard balls is firstly designed and manufactured. The transition part is mounted to the end of the robot and then the accurate centroids of balls are obtained via CMM, while the six joint angle values of the robot are acquired via serial port. The object function for robot calibration is established. After the determination of initial optimization parameters, the real D-H parameters of the robot are obtained by Levenberg-Marquardt method. The obtained real parameters are employed in the modified kinematic model and experimental results demonstrate that the robot absolute positioning accuracy is doubled.

Key words: Calibration, Coordinates measurement machine, Robot, Three-dimensional surface scanning