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Noise-induced limitations to the scalability of distributed integral control

Tegling, Emma LU and Sandberg, Henrik LU (2019) In Systems and Control Letters 130. p.23-31
Abstract

We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H2 performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The... (More)

We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H2 performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The noise's impact on performance is shown to decrease with an increased inter-nodal alignment of the local integral states. However, even though the controller can be tuned for acceptable performance for any given network size, performance will degrade as the network grows, limiting the scalability of any such controller tuning. In particular, the requirement for inter-nodal alignment increases with network size. We show that this may in practice imply that very large and sparse networks will require any integral control to be centralized, rather than distributed. In this case, the best-achievable performance scaling, which is shown to be that of proportional feedback control, is retrieved.

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author
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publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fundamental limitations, Large-scale systems, Networked control systems
in
Systems and Control Letters
volume
130
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:85068851331
ISSN
0167-6911
DOI
10.1016/j.sysconle.2019.06.005
language
English
LU publication?
no
additional info
Publisher Copyright: © 2019
id
36e086fa-07a3-4d0c-afc0-c00ce8e28dd1
date added to LUP
2021-11-24 09:52:27
date last changed
2022-04-27 06:05:43
@article{36e086fa-07a3-4d0c-afc0-c00ce8e28dd1,
  abstract     = {{<p>We study performance limitations of distributed feedback control in large-scale networked dynamical systems. Specifically, we address the question of how the performance of distributed integral control is affected by measurement noise. We consider second-order consensus-like problems modeled over a toric lattice network, and study asymptotic scalings (in network size) of H<sub>2</sub> performance metrics that quantify the variance of nodal state fluctuations. While previous studies have shown that distributed integral control fundamentally improves these performance scalings compared to distributed proportional feedback control, our results show that an explicit inclusion of measurement noise leads to the opposite conclusion. The noise's impact on performance is shown to decrease with an increased inter-nodal alignment of the local integral states. However, even though the controller can be tuned for acceptable performance for any given network size, performance will degrade as the network grows, limiting the scalability of any such controller tuning. In particular, the requirement for inter-nodal alignment increases with network size. We show that this may in practice imply that very large and sparse networks will require any integral control to be centralized, rather than distributed. In this case, the best-achievable performance scaling, which is shown to be that of proportional feedback control, is retrieved.</p>}},
  author       = {{Tegling, Emma and Sandberg, Henrik}},
  issn         = {{0167-6911}},
  keywords     = {{Fundamental limitations; Large-scale systems; Networked control systems}},
  language     = {{eng}},
  pages        = {{23--31}},
  publisher    = {{Elsevier}},
  series       = {{Systems and Control Letters}},
  title        = {{Noise-induced limitations to the scalability of distributed integral control}},
  url          = {{http://dx.doi.org/10.1016/j.sysconle.2019.06.005}},
  doi          = {{10.1016/j.sysconle.2019.06.005}},
  volume       = {{130}},
  year         = {{2019}},
}