Regression techniques for subspace-based black-box state-space system identification: an overview

As far as the identification of linear time-invariant state-space representation is concerned, among all of the solutions available in the literature, the subspace-based state-space model identification techniques have proved their efficiency in many practical cases since the beginning of the 90's. This paper introduces an overview of these techniques by focusing on their formulation as a least-squares problem. Apart from an article written by J. Qin, to the author's knowledge, such a regression formulation is not totally investigated in the books which can be considered as the references as far as subspace-based identification is concerned. Thus, in this paper, a specific attention is payed to the regression-based techniques used to identify systems working under open-loop as well as closed-loop conditions.