Tracking of triangular reference signals using LQG controllers for lateral positioning of an AFM scanner stage
Habibullah, H, Pota, HR, Petersen, IR & Rana, MS 2014, 'Tracking of triangular reference signals using LQG controllers for lateral positioning of an AFM scanner stage', IEEE/ASME Transactions on Mechatronics, vol. 19, no. 4, pp. 1105-1114.
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This paper presents the design of an internal reference model-based optimal linear quadratic Gaussian (LQG) controller for the lateral positioning of a piezoelectric tube actuator (PTA) used in an atomic force microscope (AFM). In this control design, internal modeling of the reference signal and system error are considered. As a result, 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 PTA at the resonance frequency. It achieves a high closed-loop bandwidth and significant damping of the resonant mode of the PTA, which enables a reference triangular signal to be tracked. Comparison of performance of the optimal LQG controller augmented with a vibration compensator and a PI controller demonstrates that the proposed controller shows significant improvements over the existing AFM PI controller.