Analysis of discrete-time plug-in adaptive control systems using frequency estimation

Plug in adaptive control method is technique to apply an external controller for the disturbance rejection to existing feedback system. As for the conventional plug in adaptation controller, the design has been performed under the assumption the frequency of disturbance is known. However, in the real field, there are often cases frequency of disturbance is unknown, or changes. Therefore we propose a plug in adaptive controller for unknown frequency based on the frequency estimation.