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Optimal Control Design under Structured Model Information Limitation Using Adaptive Algorithms
KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.ORCID iD: 0000-0001-9940-5929
2012 (English)Article in journal (Refereed) Submitted
Abstract [en]

Networked control strategies based on limited information about the plant model usually results in worse closed-loop performance than optimal centralized control with full plant model information. Recently, this fact has been established by utilizing the concept of competitive ratio, which is defined as the worst case ratio of the cost of a control design with limited model information to the cost of the optimal control design with full model information. In this paper, we show that with an adaptive networked controller with limited plant model information, it is indeed possible to achieve a competitive ratio equal to one. We show that an adaptive controller introduced by Campi and Kumar asymptotically achieves closed-loop performance equal to the optimal centralized controller with full model information. The plant model considered in the paper belongs to a compact set of stochastic linear time-invariant systems and the closed loop performance measure is the ergodic mean of a quadratic function of the state and control input. We illustrate the applicability of the results numerically on a vehicle platooning problem.

Place, publisher, year, edition, pages
Keyword [en]
Interconnected systems, Adaptive Control, Optimal Control, Structural Constraints
National Category
Control Engineering
URN: urn:nbn:se:kth:diva-141486OAI: diva2:697236

QS 2015

Available from: 2014-02-17 Created: 2014-02-17 Last updated: 2015-03-27Bibliographically approved
In thesis
1. Decentralized Control of Networked Systems: Information Asymmetries and Limitations
Open this publication in new window or tab >>Decentralized Control of Networked Systems: Information Asymmetries and Limitations
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Designing local controllers for networked systems is challenging, because in these systems each local controller can often access only part of the overall information on system parameters and sensor measurements. Traditional control design cannot be easily applied due to the unconventional information patterns, communication network imperfections, and design procedure complexities. How to control large-scale systems is of immediate societal importance as they appear in many emerging applications, such as intelligent transportation systems, smart grids, and energy-efficient buildings. In this thesis, we make three contributions to the problem of designing networked controller under information asymmetries and limitations.

In the first contribution, we investigate how to design local controllers to optimize a cost function using only partial knowledge of the model governing the system. Specifically, we derive some fundamental limitations in the closed-loop performance when the design of each controller only relies on local plant model information. Results are characterized in the structure of the networked system as well as in the available model information. Both deterministic and stochastic formulations are considered for the closed-loop performance and the available information. In the second contribution of the thesis, we study decision making in transportation systems using heterogeneous routing and congestion games. It is shown that a desirable global behavior can emerge from simple local strategies used by the drivers to choose departure times and routes. Finally, the third contribution is a novel stochastic sensor scheduling policy for ad-hoc networked systems, where a varying number of control loops are active at any given time. It is shown that the policy provides stochastic guarantees for the network resources dynamically allocated to each loop.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xii, 84 p.
TRITA-EE, ISSN 1653-5146 ; 2014:003
Networked Control Systems, Decentralized Control, Limited Model Information, Transportation Systems, Sensor Scheduling
National Category
Control Engineering Transport Systems and Logistics Communication Systems
urn:nbn:se:kth:diva-141492 (URN)978-91-7595-021-1 (ISBN)
Public defence
2014-03-21, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20140221

Available from: 2014-02-21 Created: 2014-02-17 Last updated: 2014-02-21Bibliographically approved

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