A New Iterative Learning Control With Time Delays for LTI Systems in Frequency Domain

In this paper, the problem of iterative learning control with time delay is studied for linear time-invariant (LTI) systems in the frequency domain. In terms of the LTI systems, which are formulated as one type of open-loop stable and minimum-phase systems with relative degree equaling to one, three different learning control schemes are proposed, such that the convergence of the tracking error can be guaranteed. The first scheme using the D-type algorithm with prediction can achieve wide convergence range. The second scheme applies an algorithm named A-type, which decreases noise. The third scheme is an improvement of the second one, which is a new type (AP-type) combination of the A-type and P-type ones. Moreover, for the systems with open-loop instability, non-minimum phase, and relative degree non-one, the convergence of the tracking error can still be ensured. Finally, some simulation examples are given to show the effectiveness of the proposed three control algorithms.