N2SID: Nuclear norm subspace identification of innovation models. (October 2016)

• Record Type: Journal Article
• Authors: Verhaegen, Michel; Hansson, Anders
• Is Part Of: Automatica. Volume 72(2016)
• Page Start: 57
• Page End: 63
• Publication Date: 2016-10
• Subjects: Subspace system identification -- Optimization -- Structural constraints -- Innovation state space models; Automatic control -- Periodicals; Automation -- Periodicals; 629.805
• DOI: 10.1016/j.automatica.2016.05.021
• Languages: English
• ISSNs: 0005-1098

Abstract

Abstract: The identification of multivariable state space models in innovation form is solved in a subspace identification framework using convex nuclear norm optimization. The convex optimization approach allows to include constraints on the unknown matrices in the data-equation characterizing subspace identification methods, such as the lower triangular block-Toeplitz of weighting matrices constructed from the Markov parameters of the unknown observer. The classical use of instrumental variables to remove the influence of the innovation term on the data equation in subspace identification is avoided. The avoidance of the instrumental variable projection step has the potential to improve the accuracy of the estimated model predictions, especially for short data length sequences.