GREAT: Grassmannian REcursive Algorithm for Tracking & Online System Identification

Fuente: arXiv
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Main Authors: Sasfi, András, Padoan, Alberto, Markovsky, Ivan, Dörfler, Florian
Format: Preprint
Published: 2024
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author Sasfi, András
Padoan, Alberto
Markovsky, Ivan
Dörfler, Florian
author_facet Sasfi, András
Padoan, Alberto
Markovsky, Ivan
Dörfler, Florian
contents This paper introduces an online approach for identifying time-varying subspaces defined by linear dynamical systems. The approach of representing linear systems by non-parametric subspace models has received significant interest in the field of data-driven control recently. This system representation enables us to provide rigorous guarantees for linear time-varying systems, which are difficult to obtain for parametric system models. The proposed method leverages optimization on the Grassmann manifold leading to the Grassmannian Recursive Algorithm for Tracking (GREAT). We view subspaces as points on the Grassmann manifold and adapt the estimate based on online data by performing optimization on the manifold. At each time step, a single measurement from the current subspace corrupted by a bounded error is available. The subspace estimate is updated online using Grassmannian gradient descent on a cost function incorporating a window of the most recent data. Under suitable assumptions on the signal-to-noise ratio of the online data and the subspace's rate of change, we establish theoretical guarantees for the resulting algorithm. More specifically, we prove an exponential convergence rate and provide an uncertainty quantification of the estimates in terms of an upper bound on their distance to the true subspace. The applicability of the proposed algorithm is demonstrated by means of numerical examples.
format Preprint
id arxiv_https___arxiv_org_abs_2412_09052
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle GREAT: Grassmannian REcursive Algorithm for Tracking & Online System Identification
Sasfi, András
Padoan, Alberto
Markovsky, Ivan
Dörfler, Florian
Systems and Control
Optimization and Control
This paper introduces an online approach for identifying time-varying subspaces defined by linear dynamical systems. The approach of representing linear systems by non-parametric subspace models has received significant interest in the field of data-driven control recently. This system representation enables us to provide rigorous guarantees for linear time-varying systems, which are difficult to obtain for parametric system models. The proposed method leverages optimization on the Grassmann manifold leading to the Grassmannian Recursive Algorithm for Tracking (GREAT). We view subspaces as points on the Grassmann manifold and adapt the estimate based on online data by performing optimization on the manifold. At each time step, a single measurement from the current subspace corrupted by a bounded error is available. The subspace estimate is updated online using Grassmannian gradient descent on a cost function incorporating a window of the most recent data. Under suitable assumptions on the signal-to-noise ratio of the online data and the subspace's rate of change, we establish theoretical guarantees for the resulting algorithm. More specifically, we prove an exponential convergence rate and provide an uncertainty quantification of the estimates in terms of an upper bound on their distance to the true subspace. The applicability of the proposed algorithm is demonstrated by means of numerical examples.
title GREAT: Grassmannian REcursive Algorithm for Tracking & Online System Identification
topic Systems and Control
Optimization and Control
url https://arxiv.org/abs/2412.09052