Nonlinearity compensation for improved nanopositioning of atomic force microscope

This article presents the design and experimental implementation of an observer-based model predictive control (OMPC) scheme with a notch filter which aims to compensate for the effects of creep, hysteresis, cross-coupling, and vibration in piezoactuators in order to improve the nanopositioning of an atomic force microscope (AFM). The controller design is based on an identified model of the piezoelectric tube scanner (PTS) for which the control scheme achieves significant compensation of its creep, hysteresis, cross-coupling, and vibration effects and ensures better tracking of the reference signal. A Kalman filter is used to obtain full-state information of the plant. The experimental results exemplify the use of this proposed control scheme.