Modeling of a piezo-actuated positioning stage based on a hysteresis observer

Piezo-actuated positioning stages contain two parts: a Piezo Electric Actuator (PEA) and a positioning mechanism. The tracking control accuracy of the piezo-actuated positioning stage is limited due to the hysteretic nonlinearity of the PEA and the friction behavior of the positioning mechanism. This loss in precision restricts the use of the piezo-actuated stage in an ultra-high-precision optical system. This paper presents an inversion-based approach to reduce the nonlinearity of the PEA by using a proposed hysteresis observer. To reduce the degredation in precision due to the friction behavior of the positioning mechanism, a PI feedback controller with a feed-forward controller based on a hysteresis observer is proposed to solve tracking problems with modelling uncertainties and external disturbances.