Contents 1 Introduction
Output regulation is one of the major concerns in control theory. The objective of output regulation is to design a tracking error feedback control for asymptotic tracking of reference signals and/or rejection of disturbances. If both the reference signal and the disturbance are generated from a linear autonomous system which is called exosystem, the problem can be solved perfectly for linear time invariant systems by the internal model principle developed in [1], [2] many results have been developed from finite-dimensional systems to infinite-dimensional systems [3]–[7]. Usually, the theories of abstraction in [8] are discussed in a broader sense,some of these abstract conditions are difficult to test for partial differential equations. In recent years, the research of output tracking from the perspective of PDE has made some progress [9]–[12]. However, in all these papers mentioned above, the frequency of harmonic disturbance are considered to be known. According to me, only a few studies in [13], [14] have been conducted on output tracking for infinite dimensional systems with unknown frequencies.
