Performance Assessment of Run-to-Run EWMA Controllers

An iterative method is developed to optimize a performance criterion for best achievable performance for discrete integral controllers used in run-to-run control. An analytical expression is derived so that a realistic assessment of the given integral controller is obtained. Using the theoretical equivalence of discrete integral and exponentially weighted moving average (EWMA) controllers, the method is then extended to performance assessment of EWMA controllers. A semiconductor manufacturing example is used to illustrate the utility of the method.