Reliable Computation of Frequency Response Plots for Nonrational Transfer Functions to Prescribed Accuracy

摘要

We propose algorithms to compute the well known Bode, Nyquist, and Nichols frequency response plots for nonrational transfer functions. The proposed algorithms are very widely applicable―the magnitude and phase functions need to be only bounded and continuous in frequency. The proposed algorithms guarantee that the magnitude and phase plots are reliably computed to a prescribed accuracy, in a finite number of iterations. Through several practical nonrational examples, we demonstrate the superior performance of the proposed algorithm over the widely used routines in MATLAB's control system toolbox and over the conventional gridding method.