3DOF nanopositioning control of an experimental tunneling current-based platform

This paper presents a 3-dimensional control of some STM-like home-made micro-/nanopositioning device equipped with piezoelectric actuators. The nonlinear effect of hysteresis and creep is compensated in both horizontal axes (X and Y) using observer-based approach, thus enabling a good trajectory tracking. The control in vertical axis (Z) is based on a quantum phenomenon of tunneling current, like in commercial STM microscope. While scanning, the obtained tunneling current is simultaneously kept on a reference value using pole placement control. The experimental results confirm that the 3DOF control in the presence of nonlinearities (hysteresis and tunneling current) as well as significant measurement noise in the latter is a quite challenging task.