On the performance of an MPC controller including a Notch filter for an AFM

The imaging performance of an atomic force microscope (AFM) at high scanning speeds is limited due to the nonlinear behavior of its scanning unit; i.e., the piezoelectric tube scanner (PTS). In order to increase the imaging speed of the AFM, a model predictive control (MPC) scheme is applied in both the X and Y piezo axes of the PTS to reduce its nonlinearity effects and a modified MPC-Notch scheme is used to improve in damping of the resonant mode. In order to verify the performance improvement achieved by the proposed schemes, scanned images from them, the existing AFM proportional-integral (PI) controller, and an open-loop AFM system are compared.