The design of model predictive control for an AFM and its impact on piezo nonlinearities

An atomic force microscope (AFM) is an extremely versatile investigative tool in the field of nanotechnology, the performance of which is significantly influenced 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 to improve in damping of the resonant mode. The proposed controller provides an AFM with the capability to achieve improved tracking and it results in the reduction of the hysteresis, creep, vibration, and cross-coupling effects in piezoactuators. The experimental results demonstrate the effectiveness of the proposed control scheme.