Nanopositioning performance of MIMO MPC

Model predictive control (MPC) refers to a class of computer control algorithms which is commonly used when tracking a reference trajectory is the primary goal. It minimizes the steady-state tracking error, increases the closed-loop bandwidth, and enables the controller to track a reference signal, the major requirements for nanopositioning applications. These capabilities of MPC controllers have motivated this research to improve the positioning performance of the piezoelectric tube scanner (PTS) for better imaging performance of an atomic force microscope (AFM). The multi-input multi-output (MIMO) form of the controller designed in this work compensates for the cross-coupling effect while the damping compensator augmented with the plant enhances its damping capability. To evaluate the performance improvement using the proposed control frame work, an experimental comparison with the existing AFM proportionalintegral (PI) controller is conducted which demonstrates that it enhances image quality for scanning speeds up to 125 Hz.