The tracking rejection of periodic signals constitutes a wide field of research in the control
theory and applications area. Repetitive Control has proven to be an efficient way to face this
topic. However in some applications the frequency of the reference disturbance signal is
time-varying or uncertain. This causes an important performance degradation in the standard
Repetitive Control scheme. This book presents some solutions to apply Repetitive Control in
varying frequency conditions without loosing steady-state performance. It also includes a
complete theoretical development and experimental results in two representative systems. The
presented solutions are organized in two complementary branches: varying sampling period
Repetitive Control and High Order Repetitive Control. The first approach allows dealing with
large range frequency variations while the second allows dealing with small range frequency
variations. The book also presents applications of the described techniques to a Rota-magnet
plant and to a power active filter device.
