Feedback Control Strategy for a High Speed Differential Piezo-Driven Stage by an Exclusive use of Piezoelectric Sensors

This paper presents the first experimental implementation of a XY differential piezo-driven stage in closed loop for tracking reference signals at the kHz with nanometer resolution by an exclusive use of piezoelectric sensors. The sensors are arranged differentially and in series with piezoelectric actuators. The control scheme consists of an internal loop with an analog damping controller and an external digital loop with an Internal Model Control (IMC) tracking controller. The damping controller is designed to attenuate the lightly damped resonances of the system. The tracking controller is especially designed for tracking only single tone sinusoidal reference trajectories. This particularity allows the use of piezoelectric transducers in a narrow frequency band and thus does not require a low frequency correction or the use of additional sensors to compensate for the high pass response of the transducers. The experimental results show that the nano-positioning stage is able to track a sinusoidal trajectory of 1 kHz frequency and 1.25 mu m amplitude with a maximum tracking error of 4 nm. These results have never been demonstrated previously with differential piezo-driven stages and open perspectives towards high speed Atomic Force Microscopy (AFM) at the nanoscale using differential actuation and piezoelectric sensing.