Repetitive Tracking Control For Linear Motor Of X-Y NC Table

This thesis takes the Natural Science Foundation project of Liaoning Province as the background and takes permanent magnet linear synchronous motor ( PMLSM ) servo system of X-Y NC table single axis drive as the research object, according to the PMLSM" zero transmission" structural features and double requirements of tracking performance and robustness for servo system of X-Y NC table , the traditional control method has been unable to meet it. therefore,in the thesis combine repetitive control and H∞optimal theory to improve the servo system performance of tracking the periodic input signal; improving the servo system tracking the multiple periodic input signal and restraining external disturbance with discrete repetitive control.The research methods are based on theoretical analysis and computer simulation. The mathematical model of PMLSM are analyzed, the vector control scheme (id=0) is confirmed in the second chapter. In order to improve servo stiffness and response speed of the system speed controller is designed as Pseudo Derivative Feedback with Feed-forward (PDFF) speed controller. To meet the high precision of tracking, to meet the high precision of tracking Displacement of X-Y NC table, displacement controllers are designed respectively against end-effects, load disturbances and some uncertainties.The servo performance of PMLSM with periodic input signal was affected by parameters variations,load disturbance and friction. Therefore,at the third chapter a robust repetitive controller was designed based on H∞optimal theory. The delay element of repetitive controller was considered as a stable perturbationΔ1(s)and the uncertainties of plant were considered as another perturbationΔ2(s),thus the servo system could be regarded as uncertainty system consisting of two perturbations, then the problem of robust repetitive control was transformed into one of H∞optimal control. Both the feedback controller and the repetitive controller could simultaneously be designed using H∞optimal theory. This control scheme not only simplifies the controller design process but also effectively improve the system tracking accuracy and robustness. On the other hand, because when the PMLSM in tracking the periodic input signal, the input signal is consist of two different cycles of the periodic signal, the accuracy of servo system to track periodic signal is decrease. The repetitive control for periodic input signal tracking effect is poor, so it is necessary to improve general repetitive controller. Therefore, in the fourth chapter, designing a multiple periods discrete repetitive controller, using two improved prototype repetitive controller not completely parallel to suppress \ tracking multiple periods input signal, the scheme effectively improves the system tracking the periodic input signal accuracy and restrain the periodic thrust fluctuation.