Optimal tracking of piezo-based nanopositioners

Abstract

This paper addresses the optimal tracking of piezo-positioners, which are fundamental tools used in high-precision positioning for nanotechnology applications. This high-precision positioning is particularly important as piezo-positioners are increasingly used in high-speed applications like nanostorage of information and nanofabrication. Precision in positioning is lost during high-speed positioning due to motion-induced dynamic vibrations in the system. These vibrations can be compensated for by using an inversion of the system dynamics to find inputs that achieve exact output tracking. Such an inversion-based approach finds the input that exactly tracks a desired output, but the resulting input may exceed available bandwidth or limits on available input amplitudes. An optimal tracking approach is used in this paper to (a) optimize the positioning trajectory, and (b) restrict trajectory to the available bandwidth and saturation limits of the amplifiers (used to apply voltage to the piezo-positioners). The approach is applied to the output tracking of a piezo-positioner and experimental results are presented.