Motion Control of the Piezoelectric Tube Scanner for Lissajous Trajectories with Modified Repetitive Control

In this paper, the modified repetitive control (MRC) approach is developed to improve the tracking performance of piezoelectric tube scanner in Atomic Force Microscope for Lissajous trajectories, which has the capability to reject the periodic tracking errors induced by hysteresis nonlinearity and the cross-coupling effect. The fundamental of Lissajous trajectory and the MRC technique are presented initially. As the plug-in feature of MRC scheme, a proportional-integral (PI) controller is also designed in feedback loop for realizing the high-precision motion control. The tracking performance of the scanner with PI+MRC is compared with the conventional PI controller to show the effectiveness of the developed method for Lissajous trajectory tracking. The desired Lissajous trajectory and the actual scan trajectory are additionally demonstrated for the scanner with different control strategies. According to the experiment results, the MRC-based technique improves the tracking performance significantly, in which the root mean square tracking error is reduced from 4328nm to 63.3nm for the scanning frequency of 25-Hz.