Iterative Learning Control (ILC) is a technique for improving the performance ofsystems or processes that operate repetitively over a ??xed time interval. The basic idea of ILCis that it exploits every possibility to incorporate past repetitive control information, such astracking errors and control input signals into the construction of the present control action.Past control information is stored and then used in the control action in order to ensure thatthe system meets the control speci??cations such as convergence. The goal of the researchpresented in this paper is to compare two different ILC techniques applied to the wafer stageof a wafer scanner motion system. Namely, we consider briefly the concepts of standard andlifted ILC and we evaluate the ILC performance in terms of tracking errors. We experiencethat ILC applied to the wafer stage has liability to deal with limited performance in the face ofposition dependent dynamics, with the fact that ILC does not account for setpoint trajectorychanges and with stochastic effects.
|Title of host publication||Proceedings of the 3rd IFAC symposium on mechatronics 2004, Sydney, Australia.|
|Place of Publication||Australia, Sydney|
|Publication status||Published - 2004|