Revisiting different adaptive observers through a unified formulation

An adaptive observer is a recursive algorithm for joint estimation of states and parameters in dynamic systems. In this paper, 4 adaptive observers published by different authors are revisited through a unified formulation. Though these algorithms are apparently quite different as presented in the original publications, typically in their design procedures they use both static and dynamic transformations which can be reformulated in a unified manner. This new perspective allows to better understand each algorithm and helps to develop new algorithm variants for particular purposes.