ABSTRACT
In classical control theory the peak of the frequency response of a closed-loop system can be determined from the intersection of the Nyquist diagram and the “M circles” (representing constant closed-loop magnitudes). The pioneering work of [159] allowed these ideas to be extended to MIMO systems, where analytical tests replaced the graphical work of Nyquist. The peak of the frequency response had other interpretations as well, generating fundamental results in robust control theory. This chapter characterizes all controllers which can yield specified upper bounds on the peak frequency response.
