Calibration test and precision analysis of small-sized hexapod parallel manipulator with high accuracy

To improve the accuracy of small-sized Hexapod parallel manipulator, calibration test and precision analysis were conducted in this paper. An error model of Hexapod was derived, and calibration procedure was designed and calibration test was conducted on 3-coordinate measuring machine (CMM). An analysis regarding the error sources of Hexapod was also conducted from the mechanical angle, and a mapping model from the gap error to the pose error of Hexapod was derived. Then the error models of least square method and Newton-Raphson iteration method in the calculation were derived and analyzed, and the identification accuracy for geometric parameters of Hexapod was analyzed. The calibration results show that after calibration, the maximum translation error of Hexapod manipulator declined from 0.2676 mm to 0.0105 mm, and the maximum rotation error declined from 0.0068 rad to 0.0011 rad. The calibration method and precision analysis method of Hexapod have a reference value for developing high precision parallel manipulators.