Abstract: Hydrostatic guideways are widely applied in ultra-precision machine tools, and the motion errors directly affects the surface accuracy of machined workpiece, so there are many researches on the motion accuracy of hydrostatic guideways. However, the models of aforementioned researches almost involve simplification, besides, the influence of the restrictor, which is considered as the key component in hydrostatic guideways, on the motion accuracy is also rarely taken into consideration. Based on kinematical theory, quasi-static theoretical model of closed hydrostatic guideway with four pads is established directly, and the effect of PM controller parameters on motion accuracy of hydrostatic guideways is analyzed. It can be found that, the position of peaks and valleys of motion error curves are not affected by the three key parameters of PM controller, but the fluctuation and PV value of motion errors. The variation mechanism of motion errors can be interpreted by the analysis of oil film reaction forces, the intense the variations of those forces, the more obvious the fluctuations of motion errors. Compared to the flow ratio Kr and the supply pressure Ps, the initial flow Q0 does have the more significant effect on motion accuracy. The research provides some reference value for the design of the hydrostatic guideways based on the PM controller.

Key words: hydrostatic guideways, motion accuracy, PM controller, motion error