Frequency-domain-based iterative learning control utilizing n-best adaptive Fourier decomposition for nonrepetitive unknown iteration-independent and iteration-varying discrete time-delay systems

The bulk of well-known control techniques for time-delay systems are sensitive to the system's uncertainty. For unknown nonrepetitive iteration-independent and iteration-varying linear discrete time-delay (LDTD) systems, an iterative learning control (ILC) design with a frequency domain identification technique is devised. The proposed ILC method is based on a novel n-best adaptive Fourier decomposition (n-BAFD) approach for approximating the unknown time-delay transfer function. An extended anticipatory ILC law is developed that uses anticipatory time to compensate for both iteration-independent and iteration-varying time delays in the frequency domain for unknown nonrepetitive LDTD systems. Three examples are used to validate the proposed frequency-domain-based ILC method.