Error Analyzing and Modeling of Six-bar Linkage Mechanism in the Parallel Machine Tool

The errors on the six bar linkage mechanism in the parallel machine tool with 5 DOF were analyzed. The main cause of the errors is manufacturing errors and installing errors of the mechanism. The relation between the former errors and the displacement of the middle point on the top edge of the six bar mechanism in the x axis is nonliear, and the relation between the later errors and the displacement is linear in the x axis. A nonlinear error modeling method based on measuring data was presented. The error polynomial function between measuring information and output of the error model was set up. With comparing the results of measuring and emulating, the model based on the method is accurate. Using the model to compensate the parallel machine tool can raise its accuracy in the x axis greatly.