Servo Designs of Piezoelectric Precision Positioning Systems
Date Issued
2009
Date
2009
Author(s)
Yeh, Yea-Chin
Abstract
Piezo-actuated micro range and nano resolution systems play important roles in metrology and process equipment technology. Two kinds of piezo-actuated optical scanning systems for modern optics are proposed in this thesis. Two scanning systems differ in its scanning capability, one requires of high resolution step-and-scan motion and the other achieves wide range and fast scan motion. This thesis proposes a modification of the learning controller called “No-reset Switching Iterative Learning Control” to deal with the repetitive error of the optical scanning systems. This method provides a constraint to the non-converging reset error experienced by most conventional iterative learning control algorithms. Its ability to alleviate the influence of the changing initial states was also illustrated. Both the simulation results and the experimental results confirm the performance of the proposed control. For some piecewise continuous references, the steady state errors of the proposed method converge to the sensor noise range (zero steady state error).lso, a piezo-actuated multi-axis nano-positioning stage for SEM based E-beam lithography system are proposed in this thesis. A tracking variable structure control with hysteresis models is employed to solve hysteresis uncertainty. The system uncertainty from hysteresis model enters the system in the forms of both matched and unmatched uncertainties. The thesis shows that the variable structure control can successfully suppress frequency-dependent hysteresis while maintaining constant servo accuracy. The control accuracy of the VSC is within 40 nm, which is greater than 40% improvement over the 75 nm accuracy maintained by the PID controller.
Subjects
piezoelectric nano-positioning system
iterative learning control
no-reset switching iterative learning control
tracking variable structure control
Type
thesis
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