A novel kinematic model of spatial five-bar linkage PPSPS for testing accuracy of two-axis moving table with ball-bar

Abstract

A novel kinematic model of spatial five-bar linkage PPSPS is presented to test the accuracy of the two-axis moving table by ball-bar for the first time in the paper. During motion measurement, the kinematic chain SPS of the ball-bar and the two prismatic pairs of the moving table constitute a five-bar linkage PPSPS. The mounting positions of the ball-bar and the directional offset between the two prismatic pairs correspond to the structure parameters of the mechanism, while the measured data of the ball-bar are regarded as the outputs of the mechanism. Hence, the mounting position errors of the ball-bar and the directional offset of the prismatic pairs are readily identified by kinematic synthesis of the PPSPS mechanism using the discrete data measured by the ball-bar, and then the errors of the moving table are obtained by the measured data minus the theoretical output of the mechanism. The model of spatial five-bar linkage PPSPS for ball-bar test of the machine table is independent of the mounting position errors and the assumption of planar motion.