Feedforward compensation for hysteresis and dynamic behaviors of a high-speed atomic force microscope scanner

Abstract

Piezoelectric actuators (PEAs) suffer from inherent creep, hysteresis, and mechanical resonances, and these phenomena have different characteristics. Creep is a low-speed phenomenon. Mechanical resonances are felt at high speeds while hysteresis is present for all speeds of operation. Some type of compensation for the weaknesses of PEAs is required to improve the tracking accuracy using PEA-based nano-positioning scanners. This work presents a feedforward compensation method for a high-speed atomic force microscope (HS-AFM) XY-scanner to mitigate the combined effects of hysteresis and scanner dynamics. Hysteresis is compensated for using an inverse Bouc-Wen (BW) model while the system dynamics are compensated for using the inverse models of the frequency response of the scanner. Cross-coupling effects at high frequencies are compensated for using low-pass filters (LPFs) to attenuate the high-frequency components of the drive signals. The compensated scanner is then used to acquire images of data tracks of a Blu-ray disk to demonstrate the efficacy of the adopted approach. The bandwidth of the scanner is limited by the choice of the LPF and the first occurrence of the scanner’s mechanical resonance.