H∞ Disturbance Observer Design
Date Issued
2009
Date
2009
Author(s)
Chen, Chi-Che
Abstract
A disturbance observer is to achieve on-line estimation of the unknown disturbance acting on a linear dynamic system. This thesis proposes a frequency shaping design of a disturbance observer that was originally proposed for estimation of special classes of disturbances. It is shown that the structure of the disturbance observer exhibits an analogy to that of a feedback control system. By taking advantage of this analogy, one can perform systematic frequency shaping re-design of the disturbance observer via the H∞ control techniques. The proposed design is arequency domain design that takes into account not only the estimation tracking ability, but also system uncertainties, and sensitivity with respect to measurement noise. The new design, unlike its ancestor, can be used to estimate most general disturbances encountered in the real world, including potentially unbounded disturbances. If one applied the proposed disturbance observer to the synthesis of disturbance rejection control, the controlled system is forced to behave as a nominal system without the interference of external disturbances or system uncertainties.
Subjects
disturbance observer
disturbance estimation
robust observer
H∞ control
frequency shaping
multivariable system
Type
thesis
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