Existence and design of observers for nonlinear systems: Relation to distance to unobservability. (English) Zbl 0933.93019

Semilinear, finite-dimensional, time-invariant control systems are considered. It is generally assumed that the system contains both a linear part and a nonlinear part which satisfies a Lipschitz type condition. First, some general remarks on nonlinear control systems are presented. Next, using the concept of observability margin (or equivalently the distance to unobservability) a systematic observer design procedure is provided. A coordinate transformation for the observer design is also discussed. Finally, as an illustrative example, the observer design procedure for a flexible link robot is studied in detail. Several remarks and comments on observer design for nonlinear control systems are also given. Similar problems have been recently considered in the paper [Y. M. Cho and R. Rajamani, IEEE Trans. Autom. Control 42, No. 4, 534-537 (1997; Zbl 0873.93049)].


93B07 Observability
93C10 Nonlinear systems in control theory
93C85 Automated systems (robots, etc.) in control theory


Zbl 0873.93049
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