Key points are not available for this paper at this time.
Two detectability notions are introduced for the most general class of linear descriptor systems. Necessary and sufficient conditions are derived for the detectabilities and for the existence of observers. Depending on existence conditions satisfied, the observers can be either in the familiar Luenberger form or in a generalized form, i.e., in descriptor form as the original system itself is. A unified procedure is provided for the design of observers in both forms.
Hou et al. (Fri,) studied this question.