
Saunder January 22, 2014 10:43 K15053˙Book
Chapter 3
Basic Nonlinear
Disturbance Observer
3.1 Introduction
In this chapter, two kinds of practical nonlinear disturbance observers are presented.
The first one is referred to as constant nonlinear disturbance observer, the estimation
error of which converges to zero if the disturbance is constant one. The second kind is
referred to as harmonic nonlinear disturbance observer. The disturbances in this case
are not limited to constant ones anymore. The amplitudes of disturbances are not
necessarily required for the observer design and analysis. However, in order to achieve
accurate estimation, the frequencies ...