Development of a novel multi-axis nano-positioning and the spiral tracking control

Abstract

This paper presents the design of a sliding-mode controller for a piezoelectric-driven nanometer resolution stage. The nanometer resolution stage is developed using the features of a flexible structure, and is driven by piezoelectric actuators and also uses capacitance sensors for position feedback. The hysteresis characteristic of the piezoelectric actuators is one of the major deficiencies in a wide variety of precise tracking positioning controls. In order to design the control system, the open-loop characteristics of this nanometer resolution stage are investigated. According to the open-loop characteristics, each pair of piezoelectric actuator and capacitance sensor is treated as an independent system and modeled as a first order linear model coupled with hysteresis. When the model is identified, the hysteresis nonlinearity is linearized then the linear system model with uncertainty is used to design the controller. When designing the controller, the sliding-mode disturbance estimation and compensation scheme is used. The structure of the proposed controller is similar to the PID controller. Thus, it can be easily implemented.