Study Of Contour Control For XY Table Based On Real-time Contour Error

The contour accuracy of XY table directly driven by two linear motors was influenced by the complicated reel-time contour error model of free-form curves, uncertainty external disturbance and dynamic matching between X axis and Y axis. To establish XY table model that easily calculated and suitable for free-form curves, real-time contour error estimate method was adopted. In order to reduce uncertainty external disturbance and dynamic matching between X axis and Y axis, in the single-axis control, PDFF controller is adopted, fuzzy control feed speed regulator was designed for speed compensation on X axis and Y axis; the iterative learning cross-coupled controller (ILCCC) was designed for current compensation on X axis and Y axis.First, according to the characteristics of linear motor XY table and the need of designing the controller, to analyze the contour error of all kinds processing track, the establishment the real-time contour error model of free-form curves is established. Because the linear motor in the process will be interfered by different uncertainties factors the controller of the linear motor XY table's the single-axis must be designed. The position feed forward controller and PDFF speed controller is adopted to enhance the system accuracy and robustness, to reduce the tracking error and indirectly to reduce the contour error. Simulation results show: Reducing only the tracking error can not completely eliminate system contour error; when joined the disturbance in the system, the contour error are very large fluctuations.Secondly, according to the relationship between feed rate in linear motor table and machining accuracy, that is, when feed rates is faster in linear motor table, the system contour error is bigger; when feed rates is lower in linear motor XY table, he system contour error is smaller. However, low feed rate will affect the processing time. In order to coordinate the contradiction between the contour error and the processing time, the controller is designed based on fuzzy control feed rate regulator and combined with the design of the single-axis controller to reduce system contour error. Simulation results show:linear motor XY table fuzzy control feed rate regulator improve the contour accuracy of the system, but reject disturbance capability is still weak.it's the need to further design the control strategy for improving contour accuracy.Thirdly, because single-axis controller and feed rate regulator can not completely solve that uncertain factors cause the system contour error, combining single-axis controller and feed rate regulator with iterative learning cross-coupled is designed. Through compensating X and Y axis's current loop constantly, it reduce directly the contour error, and to overcome the uncertainties' interference on the system. Simulation results show that:combining angle-axis controller, fuzzy control feed rate regulator with iterative learning control cross-coupling can improve accuracy and robustness of linear motor XY table system.