Graphical Nonlinear System Analysis

TL;DR

This paper introduces a graphical method using Scaled Relative Graphs (SRGs) to analyze the input-output properties and robustness of nonlinear feedback systems, extending classical control tools.

Contribution

It develops a novel graphical analysis framework for nonlinear systems using SRGs, generalizing Nyquist diagrams for nonlinear operators.

Findings

SRGs provide a visual tool for nonlinear system analysis

Distances between SRGs indicate robustness levels

The method extends classical control analysis to nonlinear feedback systems

Abstract

We use the recently introduced concept of a Scaled Relative Graph (SRG) to develop a graphical analysis of input-output properties of feedback systems. The SRG of a nonlinear operator generalizes the Nyquist diagram of an LTI system. In the spirit of classical control theory, important robustness indicators of nonlinear feedback systems are measured as distances between SRGs.