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Publications (10 of 176) Show all publications
Milosevic, J., Sandberg, H. & Johansson, K. H. (2019). A Security Index for Actuators Based on Perfect Undetectability: Properties and Approximation. In: 2018 56th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2018: . Paper presented at 56th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2018, 2 October 2018 through 5 October 2018 (pp. 235-241). Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>A Security Index for Actuators Based on Perfect Undetectability: Properties and Approximation
2019 (English)In: 2018 56th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2018, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 235-241Conference paper, Published paper (Refereed)
Abstract [en]

A novel security index based on the definition of perfect undetectability is proposed. The index is a tool that can help a control system operator to localize the most vulnerable actuators in the network. In particular, the security index of actuator i represents the minimal number of sensors and actuators that needs to be compromised in addition to i, such that a perfectly undetectable attack is possible. A method for computing this index for small scale systems is derived, and difficulties with the index once the system is of large scale are outlined. An upper bound for the index that overcomes these difficulties is then proposed. The theoretical developments are illustrated on a numerical example. 

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2019
Keywords
Computer programming, Computer science, Control engineering, Security indices, Sensors and actuators, Small-scale systems, System operator, Theoretical development, Upper Bound, Actuators
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-252077 (URN)10.1109/ALLERTON.2018.8635906 (DOI)000461021200034 ()2-s2.0-85062843906 (Scopus ID)
Conference
56th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2018, 2 October 2018 through 5 October 2018
Note

QC 20190801

Available from: 2019-08-01 Created: 2019-08-01 Last updated: 2019-08-01Bibliographically approved
Farokhi, F. & Sandberg, H. (2019). Ensuring privacy with constrained additive noise by minimizing Fisher information. Paper presented at 56th IEEE Annual Conference on Decision and Control (CDC), DEC 12-15, 2017, Melbourne, AUSTRALIA, ARKE BS, 1990, IEEE TRANSACTIONS ON INFORMATION THEORY, V36, P453. Automatica, 99, 275-288
Open this publication in new window or tab >>Ensuring privacy with constrained additive noise by minimizing Fisher information
2019 (English)In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 99, p. 275-288Article in journal (Refereed) Published
Abstract [en]

The problem of preserving the privacy of individual entries of a database when responding to linear or nonlinear queries with constrained additive noise is considered. For privacy protection, the response to the query is systematically corrupted with an additive random noise whose support is a subset or equal to a pre-defined constraint set. A measure of privacy using the inverse of the trace of the Fisher information matrix is developed. The Cramer-Rao bound relates the variance of any estimator of the database entries to the introduced privacy measure. The probability density that minimizes the trace of the Fisher information (as a proxy for maximizing the measure of privacy) is computed. An extension to dynamic problems is also presented. Finally, the results are compared to the differential privacy methodology. Crown Copyright

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Privacy, Additive constrained noise, Fisher information
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-242254 (URN)10.1016/j.automatica.2018.10.012 (DOI)000454965300031 ()2-s2.0-85056467557 (Scopus ID)
Conference
56th IEEE Annual Conference on Decision and Control (CDC), DEC 12-15, 2017, Melbourne, AUSTRALIA, ARKE BS, 1990, IEEE TRANSACTIONS ON INFORMATION THEORY, V36, P453
Note

QC 20190225

Available from: 2019-01-31 Created: 2019-01-31 Last updated: 2019-02-25Bibliographically approved
Wei, J., Yi, X., Sandberg, H. & Johansson, K. H. (2019). Nonlinear Consensus Protocols With Applications to Quantized Communication and Actuation. IEEE Transactions on Big Data, 6(2), 598-608
Open this publication in new window or tab >>Nonlinear Consensus Protocols With Applications to Quantized Communication and Actuation
2019 (English)In: IEEE Transactions on Big Data, ISSN 2325-5870, E-ISSN 2168-6750, Vol. 6, no 2, p. 598-608Article in journal (Refereed) Published
Abstract [en]

Nonlinearities are present in all real applications. Two types of general nonlinear consensus protocols are considered in this paper, namely, the systems with nonlinear communication and actuator constraints. The solutions of the systems are understood in the sense of Filippov to handle the possible discontinuity of the controllers. For each case, we prove the asymptotic stability of the systems with minimal assumptions on the nonlinearity, for both directed and undirected graphs. These results extend the literature to more general nonlinear dynamics and topologies. As applications of established theorems, we interpret the results on quantized consensus protocols.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2019
Keywords
Networks of autonomous agents, nonlinear systems, nonsmooth analysis, stability
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-254088 (URN)10.1109/TCNS.2018.2860461 (DOI)000469874200012 ()2-s2.0-85050615718 (Scopus ID)
Note

QC 20190625

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-06-25Bibliographically approved
Wiese, M., Oechtering, T. J., Johansson, K. H., Papadimitratos, P., Sandberg, H. & Skoglund, M. (2019). Secure Estimation and Zero-Error Secrecy Capacity. IEEE Transactions on Automatic Control, 64(3), 1047-1062
Open this publication in new window or tab >>Secure Estimation and Zero-Error Secrecy Capacity
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2019 (English)In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 64, no 3, p. 1047-1062Article in journal (Refereed) Published
Abstract [en]

We study the problem of securely estimating the states of an unstable dynamical system subject to non-stochastic disturbances. The estimator obtains all its information through an uncertain channel, which is subject to nonstochastic disturbances as well, and an eavesdropper obtains a disturbed version of the channel inputs through a second uncertain channel. An encoder observes and block encodes the states in such a way that, upon sending the generated codeword, the estimator's error is bounded and a security criterion is satisfied, thereby ensuring that the eavesdropper obtains as little state information as possible. Two security criteria are considered and discussed with the help of a numerical example. A sufficient condition on the uncertain wiretap channel, i.e., the pair formed by the uncertain channel from the encoder to the estimator and the uncertain channel from the encoder to the eavesdropper is derived, which ensures that a bounded estimation error and security are achieved. This condition is also shown to be necessary for a subclass of uncertain wiretap channels. To formulate the condition, the zero-error secrecy capacity of uncertain wiretap channels is introduced, i.e., the maximal rate at which data can be transmitted from the encoder to the estimator in such a way that the eavesdropper is unable to reconstruct the transmitted data. Finally, the zero-error secrecy capacity of uncertain wiretap channels is studied.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2019
Keywords
Secure state estimation, uncertain wiretap channel, zero-error secrecy capacity
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-247828 (URN)10.1109/TAC.2018.2849620 (DOI)000460415600012 ()2-s2.0-85048871914 (Scopus ID)
Note

QC 20190326

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-03-26Bibliographically approved
Umsonst, D. & Sandberg, H. (2018). A game-theoretic approach for choosing a detector tuning under stealthy sensor data attacks. In: 2018 IEEE CONFERENCE ON DECISION AND CONTROL (CDC): . Paper presented at 57th IEEE Conference on Decision and Control, CDC 2018; Centre of the Fontainebleau in Miami Beach Miami; United States; 17 December 2018 through 19 December 2018 (pp. 5975-5981). IEEE
Open this publication in new window or tab >>A game-theoretic approach for choosing a detector tuning under stealthy sensor data attacks
2018 (English)In: 2018 IEEE CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2018, p. 5975-5981Conference paper, Published paper (Refereed)
Abstract [en]

A Stackelberg game framework is presented to choose the detector tuning for a general detector class under stealthy sensor attacks. In this framework, the defender acts as a leader and chooses a detector tuning, while the attacker will follow with a stealthy attack adjusted to this tuning. The tuning chosen is optimal with respect to the cost induced by the false alarms and the attack impact. We can show that under some practical assumptions the Stackelberg game always has a solution and we state two different sufficient conditions for the uniqueness of the solution. Interestingly, these conditions show that the attack impact does not have to be a convex function. An illustrative attack scenario of a false-data injection attack shows how one can use the Stackelberg game to find the optimal detector tuning.

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE Conference on Decision and Control, ISSN 0743-1546
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-245009 (URN)10.1109/CDC.2018.8619338 (DOI)000458114805087 ()2-s2.0-85062180415 (Scopus ID)978-1-5386-1395-5 (ISBN)
Conference
57th IEEE Conference on Decision and Control, CDC 2018; Centre of the Fontainebleau in Miami Beach Miami; United States; 17 December 2018 through 19 December 2018
Projects
CERCES
Note

QC 20190305

Available from: 2019-03-05 Created: 2019-03-05 Last updated: 2019-04-04Bibliographically approved
Müller, M. I., Milosevic, J., Sandberg, H. & Rojas, C. R. (2018). A Risk-Theoretical Approach to H2-Optimal Control under Covert Attacks. In: 57th IEEE Conference on Decision and Control: . Paper presented at 57th IEEE Conference on Decision and Control (pp. 4553-4558). IEEE
Open this publication in new window or tab >>A Risk-Theoretical Approach to H2-Optimal Control under Covert Attacks
2018 (English)In: 57th IEEE Conference on Decision and Control, IEEE , 2018, p. 4553-4558Conference paper, Published paper (Refereed)
Abstract [en]

We consider the control design problem of optimizing the H-2 performance of a closed-loop system despite the presence of a malicious covert attacker. It is assumed that the attacker has incomplete knowledge on the true process we are controlling. To account for this uncertainty, we employ different measures of risk from the so called family of coherent measures of risk. In particular, we compare the closed-loop performance when a nominal value is used, with three different measures of risk: average risk, worst-case scenario and conditional valueat- risk (CVaR). Additionally, applying the approach from a previous work, we derive a convex formulation for the control design problem when CVaR is employed to quantify the risk. A numerical example illustrates the advantages of our approach.

Place, publisher, year, edition, pages
IEEE, 2018
Series
IEEE Conference on Decision and Control, ISSN 0743-1546
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-245006 (URN)10.1109/CDC.2018.8618886 (DOI)000458114804034 ()2-s2.0-85062181179 (Scopus ID)978-1-5386-1395-5 (ISBN)
Conference
57th IEEE Conference on Decision and Control
Projects
CERCES
Note

QC 20190305

Available from: 2019-03-05 Created: 2019-03-05 Last updated: 2019-08-20
Umsonst, D. & Sandberg, H. (2018). Anomaly Detector Metrics for Sensor Data Attacks in Control Systems. In: 2018 Annual American Control Conference (ACC): . Paper presented at 2018 Annual American Control Conference, ACC 2018, Wisconsin Center / Hilton Milwauke City Center, Milwauke, United States, 27 June 2018 through 29 June 2018 (pp. 153-158). Institute of Electrical and Electronics Engineers (IEEE), Article ID 8431798.
Open this publication in new window or tab >>Anomaly Detector Metrics for Sensor Data Attacks in Control Systems
2018 (English)In: 2018 Annual American Control Conference (ACC), Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 153-158, article id 8431798Conference paper, Published paper (Refereed)
Abstract [en]

We investigate worst-case impacts of stealthy full sensor attacks against linear control systems under a general class of anomaly detectors. We show that the worst-case impact scales with a parameter that is solely determined by the number of sensors in the plant, the detector used, and its tuning. Therefore, we obtain a general metric to compare the performance of detectors of this class of detectors under the investigated sensor attack, which is independent of the plant dynamics and applies to all linear systems with the same number of sensors.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Series
Proceedings of the American Control Conference, ISSN 0743-1619
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-234707 (URN)10.23919/ACC.2018.8431798 (DOI)2-s2.0-85052590291 (Scopus ID)9781538654286 (ISBN)
Conference
2018 Annual American Control Conference, ACC 2018, Wisconsin Center / Hilton Milwauke City Center, Milwauke, United States, 27 June 2018 through 29 June 2018
Projects
CERCES
Note

QC 20180910

Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-10-01Bibliographically approved
Wei, J., Verginis, C., Wu, J., Dimarogonas, D. V., Sandberg, H. & Johansson, K. H. (2018). Asymptotic and finite-time almost global attitude tracking: Representations free approach. In: 2018 European Control Conference, ECC 2018: . Paper presented at 16th European Control Conference, ECC 2018, Limassol, Cyprus, 12 June 2018 through 15 June 201816th European Control Conference, ECC 2018, Limassol, Cyprus, 12 June 2018 through 15 June 2018 (pp. 3126-3131). Institute of Electrical and Electronics Engineers (IEEE), Article ID 8550190.
Open this publication in new window or tab >>Asymptotic and finite-time almost global attitude tracking: Representations free approach
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2018 (English)In: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 3126-3131, article id 8550190Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Agents and autonomous systems, Attitude tracking, Nonlinear systems
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-241405 (URN)10.23919/ECC.2018.8550190 (DOI)2-s2.0-85059823976 (Scopus ID)9783952426982 (ISBN)
Conference
16th European Control Conference, ECC 2018, Limassol, Cyprus, 12 June 2018 through 15 June 201816th European Control Conference, ECC 2018, Limassol, Cyprus, 12 June 2018 through 15 June 2018
Note

QC 20190121

Available from: 2019-01-21 Created: 2019-01-21 Last updated: 2019-01-21Bibliographically approved
Sandberg, H. (2018). Control theory for practical cyber-physical security: Extended abstract. In: CPSS 2018 - Proceedings of the 4th ACM Workshop on Cyber-Physical System Security, Co-located with ASIA CCS 2018: . Paper presented at 4th ACM Cyber-Physical System Security Workshop, CPSS 2018, co-located with ACM AsiaCCS 2018, 4 June 2018 (pp. 25-26). Association for Computing Machinery, Inc
Open this publication in new window or tab >>Control theory for practical cyber-physical security: Extended abstract
2018 (English)In: CPSS 2018 - Proceedings of the 4th ACM Workshop on Cyber-Physical System Security, Co-located with ASIA CCS 2018, Association for Computing Machinery, Inc , 2018, p. 25-26Conference paper, Published paper (Refereed)
Abstract [en]

In this talk, we discuss how control theory can contribute to the analysis and design of secure cyber-physical systems. We start by reviewing conditions for undetectable false-data injection attacks on feedback control systems. In particular, we highlight how a physical understanding of the controlled process can guide us in the allocation of protective measures. We show that protecting only a few carefully selected actuators or sensors can give indirect protection to many more components. We then illustrate how such analysis is exploited in the design of a resilient control scheme for a microgrid energy management system.

Place, publisher, year, edition, pages
Association for Computing Machinery, Inc, 2018
Keywords
Anomaly detectors, Cyber-physical threats, Feedback control systems, Impact analysis, Adaptive control systems, Control system analysis, Embedded systems, Energy management systems, Feedback control, Network security, Anomaly detector, Controlled process, Cyber-Physical securities, Extended abstracts, False data injection attacks, Protective measures, Cyber Physical System
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-252264 (URN)10.1145/3198458.3198467 (DOI)000461237800005 ()2-s2.0-85063154826 (Scopus ID)9781450357555 (ISBN)
Conference
4th ACM Cyber-Physical System Security Workshop, CPSS 2018, co-located with ACM AsiaCCS 2018, 4 June 2018
Note

QC20190610

Available from: 2019-06-10 Created: 2019-06-10 Last updated: 2019-06-10Bibliographically approved
Teixeira, A. M. H., Araujo, J., Sandberg, H. & Johansson, K. H. (2018). Distributed Sensor and Actuator Reconfiguration for Fault-Tolerant Networked Control Systems. IEEE Transactions on Control of Network Systems, 5(4), 1517-1528
Open this publication in new window or tab >>Distributed Sensor and Actuator Reconfiguration for Fault-Tolerant Networked Control Systems
2018 (English)In: IEEE Transactions on Control of Network Systems, ISSN 2325-5870, Vol. 5, no 4, p. 1517-1528Article in journal (Refereed) Published
Abstract [en]

In this paper, we address the problem of distributed reconfiguration of networked control systems upon the removal of misbehaving sensors and actuators. In particular, we consider systems with redundant sensors and actuators cooperating to recover from faults. Reconfiguration is performed while minimizing a steady-state estimation error covariance and quadratic control cost. A model-matching condition is imposed on the reconfiguration scheme. It is shown that the reconfiguration and its underlying computation can be distributed. Using an average dwell-time approach, the stability of the distributed reconfiguration scheme under finite-time termination is analyzed. The approach is illustrated in a numerical example.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2018
Keywords
Distributed algorithms, fault-tolerant control, networked control systems
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-241219 (URN)10.1109/TCNS.2017.2732158 (DOI)000454245200002 ()2-s2.0-85028935577 (Scopus ID)
Projects
CERCES
Note

QC 20190117

Available from: 2019-01-17 Created: 2019-01-17 Last updated: 2019-03-14Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1835-2963

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