On State Observers for Nonlinear Systems: A New Design and a Unifying Framework

TL;DR

This paper introduces a new unified observer design framework for nonlinear systems, combining existing methods and demonstrating improved performance through simulations.

Contribution

It presents a novel observer design that unifies Kazantzis-Kravaris-Luenberger and parameter estimation-based observers within an immersion and invariance framework.

Findings

Proposed observer outperforms existing methods in simulations

Unified framework simplifies analysis and design

Extends applicability of nonlinear system observers

Abstract

In this paper we propose a new observer design technique for nonlinear systems. It combines the well-known Kazantzis-Kravaris-Luenberger observer and the recently introduced parameter estimation-based observer, which become special cases of it---extending the realm of applicability of both methods. A second contribution of the paper is the proof that these designs can be recast as particular cases of immersion and invariance observers---providing in this way a unified framework for their analysis and design. Simulation results of a physical system that illustrates the superior performance of the proposed observer compared to other existing observers are presented.