An extension of Mitrovic`s method: Frequency response techniques

In many feedback control problems, dynamic specifications limit both the transient response and the frequency response. Usual techniques for analysis and design are concerned with only one of these specifications, and the other is checked as often as necessary. Mitrovic´s method normally defines the roots of the characteristic equation, and design procedures adjust the locations of the roots. In this paper it is shown that the Mitrovic equations are readily solved to evaluate the closed loop frequency response with a simple graphical construction. Thus, on a single plot both the roots of the characteristic equation and the frequency response are available. In some problems bandwidth is a specific design restriction. Equations for loci of constant bandwidth are derived and the use of these loci in conjunction with the root locations and frequency response is illustrated.