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.