A closed-loop approach to reducing scan errors in nanopositioning platforms

Piezoelectric stack-actuated parallel-kinematic nanopositioning platforms have their first resonant mode at relatively low frequencies and also suffer from nonlinearities such as hysteresis and creep, resulting in a typically low-grade positioning performance. Closedloop control algorithms have shown the potential to eliminate these problems and achieve robust, repeatable nanopositioning. In this work, the performance of three commonly used damping controllers is compared based on their closed-loop noise characteristics. The best one is combined with an integrator to produce accurate raster scans of large areas while imparting substantial damping to the system and minimizing inherent nonlinearities. A scanning resolution of approximately 8nm, over a 100μm × 100μm area is achieved.