Wyniki wyszukiwania - BazTech

1

Study and analysis of discrete event-driven autonomous system with a case study for a robotics task

Raj Ravi, Kos Andrzej

Przegląd Elektrotechniczny

|

2023

|

R. 99, nr 9

50--56

EN

Highly probabilistic, potential, and dynamic domains are only relatively known to contribute classical techniques for complex system establishment impossible. Currently available technologies and strategies do not adequately address these novel needs. Thus, by enabling autonomous systems to adapt, decision-making and learning abilities, we can empower them with sufficient and appropriate expertise to recognize and address such issues. To address these requirements, discrete event-driven systems (DEDS) have been developed. This system can help the technologists of future autonomous systems by simulating the effect of auxiliary designs on the performance of the autonomous system. For modeling regular feedback of performance that is influenced by traditional techniques and depends on trust, the discrete event-driven method is most suited. This paper describes the DEDS system, the modeling of this system, and as well as the supervisory control system by explaining the supervisor, and partial supervisor. A comprehensive literature survey has been carried out in this article to explain the controllability, diagnosability, and observability potential of the DEDS system for various applications. Some of the major areas of applications such as healthcare, logistics, robotics, and banking sectors, have been discussed. Also, we have explained this system with the help of modeling a discrete event system for a queuing problem associated with robotics tasks as an example by the simulation with MATLAB 2022a. Lastly, the possible future research directions in the DEDS advancement have been provided.

PL

Wysoce probabilistyczne, potencjalne i dynamiczne domeny są znane z tego, że niemożliwe jest wniesienie klasycznych technik do tworzenia złożonych systemów. Obecnie dostępne technologie i strategie nie zaspokajają odpowiednio tych nowych potrzeb. Zatem, umożliwiając autonomicznym systemom adaptację, podejmowanie decyzji i zdolność uczenia się, możemy wyposażyć je w wystarczającą i odpowiednią wiedzę fachową, aby rozpoznawać i rozwiązywać takie problemy. Aby spełnić te wymagania, opracowano dyskretne systemy sterowane zdarzeniami (DEDS). System ten może pomóc technologom przyszłych systemów autonomicznych, symulując wpływ podsystemów pomocniczych na wydajność systemu autonomicznego. Do modelowania regularnych informacji zwrotnych na temat wyników, na które wpływają tradycyjne techniki i które zależą od zaufania, najbardziej odpowiednia jest metoda dyskretnych zdarzeń. W artykule opisano system DEDS, modelowanie tego systemu, a także system kontroli nadzorczej poprzez opisanie nadzorcy i kierownika częściowego. W tym artykule przeprowadzono obszerny przegląd literatury w celu wyjaśnienia sterowalności, diagnozowalności i potencjału obserwowalności systemu DEDS w różnych zastosowaniach. Omówiono niektóre z głównych obszarów zastosowań, takich jak sektor opieki zdrowotnej, logistyki, robotyki i bankowości. Wyjaśniliśmy również ten system za pomocą modelowania systemu zdarzeń dyskretnych dla problemu kolejkowania związanego z zadaniami robotyki na przykładzie symulacji z MATLAB 2022a. Na koniec przedstawiono możliwe przyszłe kierunki badań w zakresie rozwoju DEDS.

2

A feasible schedule for parallel assembly tasks in flexible manufacturing systems

Majdzik Paweł

International Journal of Applied Mathematics and Computer Science

|

2022

|

Vol. 32, no. 1

51--63

EN

The paper concerns the design of a framework for implementing fault-tolerant control of hybrid assembly systems that connect human operators and fully automated technical systems. The main difficulty in such systems is related to delays that result from objective factors influencing human operators’ work, e.g., fatigue, experience, etc. As the battery assembly system can be considered a firm real-time one, these delays are treated as faults. The presented approach guarantees real-time compensation of delays, and the fully automated part of the system is responsible for this compensation. The paper begins with a detailed description of a battery assembly system in which two cooperating parts can be distinguished: fully automatic and semi-automatic. The latter, nonderministic in nature, is the main focus of this paper. To describe and analyze the states of the battery assembly system, instead of the most commonly used simulation, the classic max-plus algebra with an extension allowing one to express non-deterministic human operators’ work is used. In order to synchronize tasks and schedule (according to the reference schedule) automated and human operators’ tasks, it is proposed to use a wireless IoT platform called KIS.ME. As a result, it allows a reference model of human performance to be defined using fuzzy logic. Having such a model, predictive delays tolerant planning is proposed. The final part of the paper presents the achieved results, which clearly indicate the potential benefits that can be obtained by combining the wireless KIS.ME architecture (allocated in the semi-automatic part of the system) with wired standard production networks.

3

A Unified Method to Decentralized State Detection and Fault Diagnosis/prediction of Discrete-event Systems

Zhang Kuize

Fundamenta Informaticae

|

2021

|

Vol. 181, nr 4

339--371

EN

The state detection problem and fault diagnosis/prediction problem are fundamental topics in many areas. In this paper, we consider discrete-event systems (DESs) modeled by finite-state automata (FSAs). There exist plenty of results on decentralized versions of the latter problem but there is almost no result for a decentralized version of the former problem. In this paper, we propose a decentralized version of strong detectability called co-detectability which means that if a system satisfies this property, for each generated infinite-length event sequence, in at least one location the current and subsequent states can be determined by observations in the location after a common observation time delay. We prove that the problem of verifying co-detectability of deterministic FSAs is coNP-hard. Moreover, we use a unified concurrent-composition method to give PSPACE verification algorithms for co-detectability, co-diagnosability, and co-predictability of FSAs, without any assumption on or modification of the FSAs under consideration, where co-diagnosability is first studied by [Debouk & Lafortune & Teneketzis 2000], co-predictability is first studied by [Kumar & Takai 2010]. By our proposed unified method, one can see that in order to verify co-detectability, more technical difficulties will be met compared with verifying the other two properties, because in co-detectability, generated outputs are counted, but in the latter two properties, only occurrences of events are counted. For example, when one output was generated, any number of unobservable events could have occurred. PSPACE-hardness of verifying co-diagnosability is already known in the literature. In this paper, we prove PSPACE-hardness of verifying co-predictability.

4

Lyapunov-based anomaly detection in preferential attachment networks

Ruiz Diego, Finke Jorge

International Journal of Applied Mathematics and Computer Science

|

2019

|

Vol. 29, no. 2

363--373

EN

Network models aim to explain patterns of empirical relationships based on mechanisms that operate under various principles for establishing and removing links. The principle of preferential attachment forms a basis for the well-known Barabási–Albert model, which describes a stochastic preferential attachment process where newly added nodes tend to connect to the more highly connected ones. Previous work has shown that a wide class of such models are able to recreate power law degree distributions. This paper characterizes the cumulative degree distribution of the Barabási–Albert model as an invariant set and shows that this set is not only a global attractor, but it is also stable in the sense of Lyapunov. Stability in this context means that, for all initial configurations, the cumulative degree distributions of subsequent networks remain, for all time, close to the limit distribution. We use the stability properties of the distribution to design a semi-supervised technique for the problem of anomalous event detection on networks.

5

Max-plus algebra as a tool to modelling and performance analysis of manufacturing systems

Stańczyk J.

Operations Research and Decisions

|

2018

|

Vol. 28, No. 3

77--97

EN

This contribution discusses the usefulness of (max, +) algebra as a mathematical framework for a class of manufacturing systems. This class can be described as dynamic and asynchronous, where the state transitions are initiated by events that occur at di screte instants of time. An event corresponds to the start or the end of an activity. Such systems are known as discrete event systems (DES). An overview of the concepts of modelling and analysis using the (max, +) algebra approach to DES has been given. Also, examples of manufacturing systems have been provided to illustrate the potential of this approach. The type of production process used, such as serial line, assembly line, etc., influences the modelling of different basic manufacturing systems. We have also presented the impact of the capacity of interoperable buffers. Based on an analytical model, effectiveness and performance indexes have been evaluated.

6

On-the-fly diagnosability analysis of bounded and unbounded labeled Petri nets using verifier nets

Li B., Khlif-Bouassida M., Toguéyni A.

International Journal of Applied Mathematics and Computer Science

|

2018

|

Vol. 28, no. 2

269--281

EN

This paper considers the problem of diagnosability analysis of discrete event systems modeled by labeled Petri nets (LPNs). We assume that the LPN can be bounded or unbounded with no deadlock after firing any fault transition. Our approach is novel and presents the on-the-fly diagnosability analysis using verifier nets. For a given LPN model, the verifier net and its reachability graph (for a bounded LPN) or coverability graph (for an unbounded LPN) are built on-the-fly and in parallel for diagnosability analysis. As soon as a diagnosability decision is established, the construction is stopped. This approach achieves a compromise between computation limitations due to efficiency and combinatorial explosion and it is useful to implement an engineering approach to the diagnosability analysis of complex systems.

7

Synthesis of controller for railway – level crossing devices using Petri nets and state machine

Mielnik R.

Czasopismo Techniczne. Elektrotechnika

|

2016

|

Y. 113, iss. 1-E

101--112

EN

The design of modern digital measurement-control systems applied in such fields as nuclear and power, chemical, air and rail transport as well as military requires a special approach to the philosophy of design, manufacture and the use of such systems. Therefore, attention should be focused on safeguarding the required level of reliability and safety of working conditions of such systems. On an example of a controller for an automatic railway crossing devices is presented synthesis of this controller. In this fact were used Petri nets – to modeling this controller and state machine – to make programming application.

PL

Projektowanie cyfrowych systemów pomiarowo-sterujących stosowanych w takich obszarach jak: energetyka jądrowa, przemysł chemiczny, transport powietrzny i kolejowy oraz zastosowania militarne wymaga specjalnego podejścia do filozofii projektowania, produkcji i eksploatacji tego typu. Systemy te wymagają zapewnienia odpowiedniego poziomu niezawodności i bezpieczeństwa. Na przykładzie sterownika samoczynnej sygnalizacji przejazdowej przedstawiono jego syntezę z wykorzystaniem sieci Petriego – do modelowania funkcji kontrolera, oraz maszyny stanów – do wykonania oprogramowania.

8

Event monitoring of parallel computations

Gruzlikov A. M., Kolesov N. V., Tolmacheva M. V.

International Journal of Applied Mathematics and Computer Science

|

2015

|

Vol. 25, no. 2

311--321

EN

The paper considers the monitoring of parallel computations for detection of abnormal events. It is assumed that computations are organized according to an event model, and monitoring is based on specific test sequences.

9

Implementacja biblioteki modelowania układów zdarzeń dyskretnych opartej na języku CSL, z wykorzystaniem platformy .NET

Wyciślik Ł., Wiejak P.

Studia Informatica

|

2013

|

Vol. 34, nr 2B

275--282

PL

Artykuł przedstawia bibliotekę służącą do modelowania układów zdarzeń dyskretnych według koncepcji wyboru działania, opartą na języku CSL. Cechą charakterystyczną rozwiązania jest zastosowanie platformy .NET oraz języka C#. Duża popularność tych technologii sprawia, że budowa modeli jest możliwa już przy minimalnym nakładzie związanym z zapoznaniem się z API samej biblioteki.

EN

The article presents the library used to discrete events systems modeling based on CSL language. The key point of this implementation is involving of .NET platform and C# language. Big popularity of these technologies makes that building of models is possible with minimal effort related to study of library API.

10

FDI(R) for satellites: how to deal with high availability and robustness in the space domain?

Olive X.

International Journal of Applied Mathematics and Computer Science

|

2012

|

Vol. 22, no. 1

99-107

EN

The European leader for satellite systems and at the forefront of orbital infrastructures, Thales Alenia Space, is a joint venture between Thales (67%) and Finmeccanica (33%) and forms with Telespazio a Space Alliance. Thales Alenia Space is a worldwide reference in telecoms, radar and optical Earth observation, defence and security, navigation and science. It has 11 industrial sites in 4 European countries (France, Italy, Spain and Belgium) with over 7200 employees worldwide. Satellite evolution and the wish to design more autonomous missions imply the enhancement of the satellite architecture and special attention paid to fault management (i.e., Fault Detection, Isolation and Recovery, or FDIR, in space). Nevertheless, the constraints on FDIR techniques and strategies remain the same as for standard missions: robustness, reactive detection, quick isolation/identification and validation. This paper gives an introduction to Fault Tolerance (FT) in the space domain and some principles for the coming FT architectures. The current context of FDIR is presented by describing the approach implemented on telecommunication satellites and, more precisely, on one of the most FDIR sensible subsystems: the AOCS (Attitude and Orbit Control System). Following the current state of FDIR in the space domain, some perspectives are given such as a centralized distributed FDIR strategy for the next generation of autonomous satellites as well as some research tracks and hybrid diagnosis.

11

Deadlock freeness supervisor for marked graph

Sioud H., Achour Z., Sava A., Rezg N.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2009

|

Vol. 57, nr 3

281-289

EN

This note presents a control synthesis approach for discrete event systems modeled by marked graphs with uncontrollable transitions. The forbidden behavior is specified by General Mutual Exclusion Constraints (GMEC). We prove that, even if the system to be controlled .s live, the closed loop control may generate deadlock situations. Using the structural proprieties of marked graph we defined the causes of deadlock situations, and we defined a formal method to avoid them.

12

Diagnosis-time assessment in discrete event systems using timed Petri nets

Tabakow I.

Systems Science

|

2008

|

Vol. 34, no 3

17-23

EN

This paper describes a method of diagnosis-time assessment in discrete event systems. Any such system is modelled by a live, bounded, and reversible place-transition Petri net N. There are assumed some deterministically given delays associated with the transitions of N, and hence, N is assumed to be deterministic timed. Without loss of generality, the single place fault model is considered below and the corresponding diagnosis process is assumed to be sequential. The notions of D-partition of the set of places P of a given place-transition net N and net k-distinguishability are first introduced. Then, the corresponding net place invariants are computed. The system k-distinguishability measure is obtained in a unique way from the place-invariant matrix. For a large value of k, the system model is extended by using some set of additional places called test points and at the same time preserving the original net properties. In accordance with the above assumption of sequential fault diagnosis, the process of fault isolation is carried out step by step, where each step depends on the result of the diagnostic experiment at the previous step. Hence, the diagnosis-time assessment is realised by computing the absolute value of the time difference between the minimum cycle time of N and the worst-case fault-isolation time according to the diagnostic tree obtained. The complexity of the method proposed depends on the effectivity of the existing algorithms for computation of the P-cover, i.e., the set of P-invariants covering N. The approach proposed can be extended to higher level Petri nets, e.g., such as coloured ones. Several examples are given.

13

Modular control of large distributed discrete event systems

Komenda J.

Systems Science

|

2004

|

Vol. 30, no 1

51-63

EN

Coalgebra and coinduction provide new results and insights for modular supervisory control of discrete-event systems (DES), where the overall system is composed of subsystems that are combined in synchronous (parallel) product. Modular supervisory control is studied within the coalgebraic framework. Coinduction has been used to define an operation on languages called supervised product, and synchronous product is defined by coinduction. We have shown recently that the supremal controllable sublanguage of a given language can be defined by coinduction as well. We study the commutativity between the synchronous product and supremal controllable and normal sublanguage. The results guarantee that under the conditions derived in the paper control synthesis can be done locally without affecting the optimality of the solution.

14

Dynamic control of a class of discrete event systems using a state reconstruction algorithm

Martinelli F., Nicosia S., Valigi P.

Control and Cybernetics

|

2000

|

Vol. 29, no 1

275-294

EN

The problem of dynamic control of Discrete Event Dynamic Systems (DEDS) is addressed in this paper as a dynamic optimization problem : some resources must be allocated to the system in order to optimize a performance function which is assumed time-varying. The control scheme exploits a state reconstruction algorithm to compute an estimate of the performance for perturbed sample paths. The algorithm is based on the use of data extracted from the observation of the system and allows to accurately reconstruct its state behavior, for resource allocations different from the nominal one. The proposed control scheme is then used for dynamic allocation of buffer capacities in mamlfaeturing systems, such as Kanban systems. A parallel implementation of the whole algorithm is also mentioned.