A Frequency Domain Approach to Robust Adaptive Control

This paper presents a frequency domain approach to robust adaptive control. The main idea is to compensate the open-loop frequency response to meet a frequency domain specification. This frequency domain approach has the following advantages compared with the time domain approach: 1) no parametric representations of the plant are needed, 2) a priori informations about the plant and disturbances in the frequency domain are incorporated in a natural way, 3) the controller is updated only in those frequencies where the reference signal is rich. Conditions to guarantee the global stability of the closed-loop system are established. Simulations are presented to illustrate the relevant points of this work.