The main concern of this thesis is to improve the imaging performance of an Atomic Force Microscope (AFM). According to the purpose of this work, an internal reference model-based optimal Linear Quadratic Gaussian (LQG) controller is designed for the lateral positioning of a Piezoelectric Tube Scanner (PTS) used in the AFM. In this control design, a reference signal modeling and the system positioning error are considered and the steady-state tracking error is minimized. In addition to the LQG controller, a vibration compensator is incorporated with the plant to suppress the vibration of the PTS at the resonant frequency. Consequently, it achieves a high closed-loop bandwidth and adds significant damping to the resonant mode of the PTS, which enables the reference triangular signal to be tracked. Comparisons of the performance of the proposed controller and the built-in AFM PI controller demonstrate that the proposed control scheme shows significant improvement over the existing in-built AFM PI controller.
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