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1

Iterative learning fault-tolerant control for the networked control systems with initial state disturbance

Xingjian Fu, Qianjun Zhao

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 3

art. no. e140934

EN

The iterative learning fault-tolerant control strategies with non-strict repetitive initial state disturbances are studied for the linear discrete networked control systems (NCSs) and the nonlinear discrete NCSs. In order to reduce the influence of the initial state disturbance in iteration, for the linear NCSs, considering the external disturbance and actuator failure, the iterative learning fault-tolerant control strategy with impulse function is proposed. For the nonlinear NCSs, the external disturbance, packet loss and actuator failure are considered, the iterative learning fault-tolerant control strategy with random Bernoulli sequence is provided. Finally, the proposed control strategies are used for simulation research for the linear NCSs and the nonlinear NCSs. The results show that both strategies can reduce the influence of the initial state disturbance on the tracking effect, which verifies the effectiveness of the given method.

2

Design of decoupled pi controllers for two-input two-output networked control systems with intrinsic and network-induced time delays

Mohamed-Vall Ould Mohamed

Acta Mechanica et Automatica

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2021

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Vol. 15, no. 4

201--208

EN

Proportional integral controller design for two-input two-output (TITO) networked control systems (NCSs) with intrinsic and network-induced time delays is studied in this paper. The TITO NCS consists of two delayed sub-systems coupled in a 1-1/2-2 pairing mode. In order to simplify the controller design, a decoupling method is first applied to obtain a decoupled system. Then, the controllers are designed based on the transfer function matrix of the obtained decoupled system and using the boundary locus method for determining the stability region and the well-known Mikhailov criterion for the stability test. A comparative analysis of the designed controllers and other controllers proposed in previous literature works is thereafter carried out. To demonstrate the validity and efficacy of the proposed method and to show that it achieves better results than other methods proposed in earlier literature works, the implementation in simulation of Wood–Berry distillation column model (methanol–water separation), a well-known benchmark for TITO systems, is carried out.

3

Secure web access to mini distributed control system

Rzońca D., Stec A., Trybus B.

Automatyka / Automatics

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2012

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Vol. 16, no. 2

155-164

EN

Small distributed control systems with remote web access are becoming fairly common. Sooner or later, security of such systems will become a precondition for some critical applications. However, limited computational power will reąuire some non-standard solutions. The paper describes secure web access to a prototype of small distributed control system programmed according to IEC 61131-3 standard. Security is provided by challenge-response authentication of web client and symmetric cryptographic primitives. Communication latency is analysed by means of a Timed Petri Net model.

PL

Niewielkie rozproszone systemy sterowania ze zdalnym dostępem przez stronę www stają się coraz bardziej powszechne. Wcześniej bądź później w istotnych zastosowaniach będą wymagane zabezpieczenia takich systemów. Ograniczona moc obliczeniowa wymusza jednakże opracowanie niestandardowych rozwiązań. Artykuł opisuje bezpieczny dostęp internetowy do prototypowego niewielkiego rozproszonego systemu sterowania, programowalnego zgodnie z normą IEC 61131-3. Bezpieczeństwo oparte jest na uwierzytelnianiu challenge-response klienta webowego i kryptografii symetrycznej. Opóźnienie komunikacji zostało przeanalizowane bazując na modelu w czasowych sieciach Petriego.

4

Approach to the design of robust networked control systems

Morawski M., Zajączkowski A. M.

International Journal of Applied Mathematics and Computer Science

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2010

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Vol. 20, no 4

689-698

EN

The paper describes the application of the traffic engineering framework together with application layer procedures as mechanisms for the reduction of network latency lags. These mechanisms allow using standard and inexpensive hardware and software technologies typically applied for office networking as a means of realising networked control systems (NCSs) with high dynamic control plants, where a high dynamic control plant is the one that requires the sampling period several times shorter than communication lags induced by a network. The general discussion is illustrated by experimental results obtained in a laboratory NCS with the magnetic levitation system (MLS), which is an example of a structurally unstable plant of high dynamics.

5

Fault diagnosis of networked control systems

Aubrun C., Sauter D., Yamé J.

International Journal of Applied Mathematics and Computer Science

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2008

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Vol. 18, no 4

525-537

EN

Networked Control Systems (NCSs) deal with feedback control systems with loops closed via data communication networks. Control over a network has many advantages compared with traditionally controlled systems, such as a lower implementation cost, reduced wiring, simpler installation and maintenance and higher reliability. Nevertheless, the network-induced delay, packet dropout, asynchronous behavior and other specificities of networks will degrade the performance of closed-loop systems. In this context, it is necessary to develop a new theory for systems that operate in a distributed and asynchronous environment. Research on Fault Detection and Isolation (FDI) for NCSs has received increasing attention in recent years. This paper reviews the state of the art in this topic.