Robust high-order repetitive control

High-order repetitive control has previously been introduced to either improve the robustness for period-time uncertainty or reduce the sensitivity to non-periodic inputs of standard repetitive control schemes. This paper presents a systematic, semidefinite programming based approach to compute high-order repetitive controllers that yield an optimal trade-off between these two performance criteria. Additionally, the capability of the proposed design approach to reproduce and outperform existing high-order repetitive control approaches is illustrated.