| 1. |
- Andersson, G., et al.
(författare)
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Cyber-security of SCADA systems
- 2012
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Ingår i: 2012 IEEE PES Innovative Smart Grid Technologies, ISGT 2012. - : IEEE. - 9781457721588 ; , s. 6175543-
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Konferensbidrag (refereegranskat)abstract
- After a general introduction of the VIKING EU FP7 project two specific cyber-attack mechanisms, which have been analyzed in the VIKING project, will be discussed in more detail. Firstly an attack and its consequences on the Automatic Generation Control (AGC) in a power system are investigated, and secondly the cyber security of State Estimators in SCADA systems is scrutinized.
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| 2. |
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| 3. |
- D'Innocenzo, A., et al.
(författare)
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Scalable scheduling algorithms for wireless networked control systems
- 2009
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Ingår i: 2009 IEEE INTERNATIONAL CONFERENCE ON AUTOMATION SCIENCE AND ENGINEERING. - : IEEE. - 9781424445783 ; , s. 409-414
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Konferensbidrag (refereegranskat)abstract
- In this paper, we address the problem of designing scalable scheduling and routing policies over a time-triggered multi-hop control network, when closing a considerable number of control loops on the same network. The key idea is to formally define by means of regular languages the set of schedules for each control loop that satisfy a given control specification, and to exploit operators on regular languages to compute the set of schedules for the whole system. In order to test our methodology, we address a mineral floatation control problem derived from the Boliden (a swedish mining company) mine in Garpenberg, and propose a scheduling solution that can be implemented on systems compliant with communication protocols for wireless networks (e.g. the WirelessHART specification).
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| 4. |
- Ishizaki, T., et al.
(författare)
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Structured model reduction of interconnected linear systems based on singular perturbation
- 2013
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Ingår i: Proceedings of the American Control Conference 2013. - : American Automatic Control Council. - 9781479901777 ; , s. 5524-5529
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a singular perturbation approximation that preserves system passivity and an interconnection topology among subsystems. In the first half of this paper, we develop a singular perturbation approximation valid for stable linear systems. Using the relation between the singular perturbation and the reciprocal transformation, we derive a tractable expression of the error system in the Laplace domain, which provides a novel insight to regulate the approximating quality of reduced models. Then in the second half, we develop a structured singular perturbation approximation that focuses on a class of interconnected systems. This structured approximation provides a reduced model that not only possesses fine approximating quality, but also preserves the original interconnection topology and system passivity.
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| 5. |
- Ishizakiy, T., et al.
(författare)
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Singular perturbation approximation of semistable linear systems
- 2013
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Ingår i: 2013 European Control Conference, ECC 2013. - : IEEE. - 9783033039629 ; , s. 4508-4513
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a singular perturbation approximation for semistable linear systems. In particular, we derive a novel expression of error systems in the Laplace domain. As a result, we obtain an h2-error bound in terms of the sum of eigenvalues of an index matrix, which coincides with a controllability gramian of the state-derivative. Furthermore, we show that the singular perturbation model appropriately preserves the semistability of the original system and also guarantees the stability of the error system. The efficiency of the proposed method is shown through a numerical example of a Markov chain model approximation.
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| 6. |
- Johansson, Alexander, et al.
(författare)
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Optimization of the H∞-norm of Dynamic Flow Networks
- 2018
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Ingår i: 2018 Annual American Control Conference (ACC). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1280-1285
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study the H∞-norm of linear systems over graphs, which is used to model distribution networks. In particular, we aim to minimize the H∞-norm subject to allocation of the weights on the edges. The optimization problem is formulated with LMI (Linear-Matrix-Inequality) constraints. For distribution networks with one port, i.e., SISO systems, we show that the H∞-norm coincides with the effective resistance between the nodes in the port. Moreover, we derive an upper bound of the H∞-norm, which is in terms of the algebraic connectivity of the graph on which the distribution network is defined.
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| 7. |
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| 8. |
- Sadamoto, T., et al.
(författare)
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Weak resilience of networked control systems
- 2017
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Ingår i: 2016 European Control Conference, ECC 2016. - : IEEE. - 9781509025916 ; , s. 977-982
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a method to establish a networked control system that maintains its stability in the presence of certain undesirable incidents on local controllers. We call such networked control systems weakly resilient. We first derive a necessary and sufficient condition for the weak resilience of networked systems. Networked systems do not generally satisfy this condition. Therefore, we provide a method for designing a compensator which ensures the weak resilience of the compensated system. Finally, we illustrate the efficiency of the proposed method by a power system example based on the IEEE 14-bus test system.
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| 9. |
- Wei, Jieqiang, et al.
(författare)
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Asymptotic and finite-time almost global attitude tracking : Representations free approach
- 2018
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Ingår i: 2018 European Control Conference, ECC 2018. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426982 ; , s. 3126-3131
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Konferensbidrag (refereegranskat)abstract
- In this paper, the attitude tracking problem is considered using the rotation matrices. Due to the inherent topological restriction, it is impossible to achieve global attractivity with any continuous attitude control system on SO(3). Hence in this work, we propose some control protocols achieving almost global tracking asymptotically and in finite time, respectively. In these protocols, no world frame is needed and only relative state information are requested. For finitetime tracking case, Filippov solutions and non-smooth analysis techniques are adopted to handle the discontinuities. Simulation examples are provided to verify the performances of the control protocols designed in this paper.
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| 10. |
- Wiese, Moritz, et al.
(författare)
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Secure Estimation for Unstable Systems
- 2016
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Ingår i: 2016 IEEE 55th Conference on Decision and Control, CDC 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509018376 ; , s. 5059-5064
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Konferensbidrag (refereegranskat)abstract
- We assume that the states of an unstable dynamical system are encoded and sent to an estimator through an uncertain channel, which is a channel disturbing its inputs in a nonstochastic manner. The encoder's codeword is also fed into another uncertain channel, at whose output an eavesdropper is listening. The estimator should obtain a uniformly bounded system state estimation error, whereas the eavesdropper's information about the system states should be subject to a security constraint. We find a condition on the relation between the uncertain channel from encoder to estimator and the uncertain channel from encoder to eavesdropper which if satisfied allows for at least one of the two following security criteria to hold: The volume of the set of states possible acccording to the eavesdropper's information tends to infinity at exponential speed-by itself (strong security) or if divided by the volume of the set of states possible according to the estimator's information (weak security).
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