Abstract:

Proposed in this paper is an improved method of error modeling and kinematic calibration for a special 3-DOF planar parallel alignment platform for screen printing. In the investigation,first,based on the characteristics of planar alignment mechanisms,the mapping relationship between the errors of position and orientation and the errors of geometric parameters is derived by using the vector method and the analytical method. Next,the Jacobin error matrix is obtained. Then,the influences of all geometric error sources of the mechanism on the terminal pose errors are estimated via the sensitivity analysis. Moreover,the main error sources of geometric parameters to be calibrated are determined through an identification analysis,and several configurations are selected to construct a matrix for the error identification of geometric parameters through Matlab simulation,with a difference between the identified and the assumed values,which is less than 5%,being obtained. Finally,a calibration experiment is carried out by using a dual-frequency laser interferometer and a dial indicator,and the results verify the effectiveness and practicability of the proposed calibration method.

Key words: XY-Theta parallel platform, orientation error, error modeling, sensitivity analysis, kinematic calibration