On a nonlinear observer with pseudo-linearized error dynamics

The problem of selecting state and output coordinate changes that transform a given nonlinear system into a pseudoobserver form is considered. A system in this form has the property that its family of linearizations about constant operating points is in observer form in the sense of linear systems. For a system in pseudoobserver form, it is straightforward to construct a state observer with the property that the family of linearized error systems is independent of the operating point. Therefore, the error dynamics are said to be pseudolinearized. Such an observer can then be used as part of a stabilizing dynamic output feedback control law