Precision contour control of XY table based on LuGre model friction compensation

The contour accuracy of XY table directly driven by two linear motors was influenced by nonlinear friction of dynamic system. On the basis of analyzing the contour error of the system, the control strategy combining state observer and sliding-model controller with the cross coupling controller (CCC) was presented in the paper. A sliding-model state observer was proposed to estimate state z which was not measured. Based on the estimated friction state, the sliding-model controller was designed to compensate the effect of friction that act on the XY table, and reduce the position tracking error. The stability of the sliding-model controller with sliding-mode observer was analyzed. CCC can eliminate the influence of the gain parameter and dynamic parameter mismatch between two axes to further reduce the contour error. The simulation results show that the proposed control method can reduce the effect to XY table performance and achieve the XY table high accuracy contour control in the presence of friction.