ILC With Time-Varying Delay Estimation: A Case Study on Twin Roll Strip Casting

Abstract

In this paper we propose an iterative learning control (ILC) algorithm for a class of periodic processes with a variable time-delay that is greater than one iteration in length. We estimate the delay by separating it into two components: an estimate based on the number of iterations contained within a single delay period and an estimate defined as the residual between the actual delay and the iteration-based estimate. This structure enables the derivation of a stability law for an ILC algorithm that is a function of the delay estimation error. The proposed ILC algorithm is then applied to twin roll strip casting and the results are validated using experimental process data. We also demonstrate the sensitivity of the ILC algorithm to estimation error through simulation results.