An Algorithm for Computer-Aided Loop Shaping

Presented in this paper is an algorithm that facilitates computer-aided loop shaping and it is directly applicable to the Quantitative Feedback Theory (QFT) problem. The algorithm is based on converting the problem of designing an Open Loop Transfer Function (OLTF), whose magnitude and phase at each frequency lies in some allowable region in the complex plane, into a parameter identification problem. The outcome of the identification process is a pulse transfer function representation of the loop which in turn can be transformed into the s-domain giving the desired OLTF.