| 1. |
- Frisk, Erik, 1971-, et al.
(författare)
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A toolbox for design of diagnosis systems
- 2006
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Ingår i: IFAC Safeprocess06,2006. - Beijing, China : IFAC. ; , s. 703-
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Konferensbidrag (refereegranskat)abstract
- Design of diagnosis systems is a complex task that involves many different steps. Full understanding of all different parts of the design procedure requires deep knowledge on theory from a wide variety of subjects. Thus, to encourage the use of results from diagnosis research it is highly desirable to have software support in the design process. This paper describes ongoing work for determining an architecture for such a toolbox. The paper also describes software solutions in the toolbox. In industry as well as in universities, Matlab is probably the most widespread tool used by control engineers. Therefore the toolbox is primarily based upon Matlab but also some computer algebraic tools such as Mathematica and Maple are used.
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| 2. |
- Krysander, Mattias, 1977-, et al.
(författare)
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An Efficient Algorithm for Finding Minimal Overconstrained Subsystems for Model-Based Diagnosis
- 2008
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Ingår i: IEEE transactions on systems, man and cybernetics. Part A. Systems and humans. - 1083-4427 .- 1558-2426. ; 38:1, s. 197-206
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Tidskriftsartikel (refereegranskat)abstract
- In model based diagnosis, the diagnostic system construction is based on a model of the technical system to be diagnosed. To handle large differential algebraic models and to achieve fault isolation, a common strategy is to pick out small over-constrained parts of the model and to test these separately against measured signals. A new algorithm for computing all minimal over-constrained sub-systems in a model is proposed. For complexity comparison, previous algorithms are recalled. It is shown that the time complexity under certain conditions is much better for the new algorithm. This is illustrated using a truck engine model.
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| 3. |
- Krysander, Mattias, 1977-, et al.
(författare)
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An Efficient Algorithm for Finding Over-constrained Sub-systems for Construction of Diagnostic Tests
- 2005
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Ingår i: 16th International Workshop on Principles of Diagnosis DX-05,2005. - Pacific Grove, California, USA. ; , s. 55-60
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Konferensbidrag (refereegranskat)abstract
- In this paper, a new algorithm for computing all minimal over-constrained sub-systems in a structural model is proposed. To handle large differential algebraic models in diagnosis, systematic structural approaches to find testable sub-systems have been suggested. It is shown how the algorithm can be incorporated and improve some of them. Previous algorithms are recalled and it is shown that the new algorithm is 14000 times faster when applied to a Scania truck engine model.
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| 4. |
- Krysander, Mattias, 1977-, et al.
(författare)
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Fault Isolability Prediction of Diagnostic Models
- 2005
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Ingår i: 16th International Workshop on Principles of Diagnosis DX-05,2005. - Pacific Grove, California, USA. ; , s. 163-168
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Konferensbidrag (refereegranskat)abstract
- Fault isolability plays a significant role and could be critical with respect to many aspects such as safety and maintenance for a process to be diagnosed. In the development of processes including diagnosis, design decisions are taken, e.g. sensor configuration selection, which affects the fault isolability possibilities. In this paper an algorithm for predicting fault isolability possibilities using a structural model describing the process is proposed. Since only a structural model is needed as input, the algorithm can easily predict fault isolability possibilities of different design concepts. In contrast to previous algorithms using structural models no assumption is imposed on the model. The algorithm computes faults that cannot be distinguished from other faults, which can be used to exclude design alternatives with insufficient isolability possibility.
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| 5. |
- Krysander, Mattias, 1977-, et al.
(författare)
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Statistical Properties and Design Criterions for Fault Isolation in Noisy Systems
- 2008
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Ingår i: 19th International Workshop on Principles of Diagnosis, DX,2008. - Sydney, Australia : DX.
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Konferensbidrag (refereegranskat)abstract
- Fault diagnosis in the presence of noise and model errors is of fundamental importance. In the paper, the meaning of fault isolation performance is formalized by using the established notion of coverage and false coverage from the field of statistics. Then formal relations describing the relationship between fault isolation performance and the residual related design parameters are derived. For small faults, the measures coverage and false coverage are not applicable so therefore, a different performance criteria, called sub-coverage, is proposed. The performance of different AI-based fault isolation schemes is evaluated and it is notably shown that the well known principle of minimal cardinality diagnosis gives a bad performance. Finally, some general design guidelines that guarantee and maximize the fault isolation performance are proposed.
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| 6. |
- Krysander, Mattias, 1977-, et al.
(författare)
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Structural Analysis for Fault Diagnosis of DAE Systems Utilizing Graph Theory and MSS Sets
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- When designing model-based fault-diagnostic systems, the use of consistency relations (also called e.g. parity relations) is a common choice. Different consistency relations are sensitive to different subsets of faults, and thereby isolation can be achieved. This report presents an algorithm for finding a small set of submodels that can be used to derive consistency relations with highest possible diagnosis capability. The algorithm handles differential-algebraic models and is based on graph theoretical reasoning about the structure of the model. An important step towards finding these submodels, and therefore also towards finding consistency relations, is to find all minimal structurally singular (MSS) sets of equations. These sets characterize the fault diagnosability. The algorithm is applied to a large nonlinear industrial example, a part of a paper plant. In spite of the complexity of this process, a small set of consistency relations with high diagnosis capability is successfully derived.
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| 7. |
- Nyberg, Mattias, 1970-, et al.
(författare)
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Statistical Properties and Design Criterions for AI-Based Fault Isolation
- 2008
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Ingår i: IFAC World Congress,2008. - Seoul, Korea : IFAC.
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Konferensbidrag (refereegranskat)abstract
- Fault diagnosis in the presence of noise and model errors is of fundamental importance. In the paper, the meaning of fault isolation performance is formalized by using the established notion of coverage and false coverage from the field of statistics. Then formal relations describing the relationship between fault isolation performance and the residual related design parameters are derived. For small faults, the measures coverage and false coverage are not applicable so therefore, a different performance criteria, called sub-coverage, is proposed. The performance of different AI-based fault isolation schemes is evaluated and it is shown that the well known principle of minimal cardinality diagnosis gives a very bad performance. Finally, some general design guidelines that guarantee and maximize the fault isolation performance are proposed.
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| 8. |
- Biteus, Jonas, 1977-, et al.
(författare)
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An algorithm for computing the diagnoses with minimal cardinality in a distributed system
- 2008
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 21:2, s. 269-276
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Tidskriftsartikel (refereegranskat)abstract
- In fault diagnosis, the set of minimal diagnoses is commonly calculated. However, due to for example limited computation resources, the search for the set of minimal diagnoses is in some applications focused on to the smaller set of diagnoses with minimal cardinality. The key contribution in this paper is an algorithm that calculates the diagnoses with minimal cardinality in a distributed system. The algorithm is constructed such that the computationally intensive tasks are distributed to the different units in the distributed system, and thereby reduces the need for a powerful central diagnostic unit. © 2007 Elsevier Ltd. All rights reserved.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Biteus, Jonas, 1977-, et al.
(författare)
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Determining the Fault Status of a Component and its Readiness, with a Distributed Automotive Application
- 2009
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Ingår i: Engineering applications of artificial intelligence. - : Elsevier BV. - 0952-1976 .- 1873-6769. ; 22:3, s. 363-373
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Tidskriftsartikel (refereegranskat)abstract
- In systems using only single-component tests, the fault status of a component is ready if a test only supervising the component has been evaluated. However, if plausibility tests that supervise multiple components are used, then a component can be ready before all tests supervising the component have been evaluated. Based on test results, this paper contributes with conditions on when a component is ready. The conditions on readiness are given for both centralized and distributed systems and are here applied to the distributed diagnostic system in an automotive vehicle.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Frisk, Erik, 1971-, et al.
(författare)
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Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-Algebraic Equations (revised)
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Linear residual generation for DAE systems has been considered. In all results derived, no distinction between input and output signals is done. A complete characterization and parameterization of all residual generators is presented. Further, a condition for fault detectability in DAE systems is given. Based on the characterization of all residual generators, a design strategy for residual generators for DAE systems is presented. Given that a set of faults are detectable, the design strategy will result in a residual generator sensitive to all the detectable faults. Further the residual generator is guaranteed to be of lowest possible order. Special care has been devoted to assure this property also for non-controllable systems.
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| 18. |
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| 19. |
- Frisk, Erik, 1971-, et al.
(författare)
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Using Minimal Polynomial Bases for Model-Based Fault Diagnosis : A Demonstration Document for PolyX, Ltd
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This document is a demonstration document, demonstrating the use of the Polynomial Toolbox for Matlab when designing residual generators for fault diagnosis. A brief introduction to the residual generation problem for fault diagnosis in linear systems is given and a solution based on polynomial methods are outlined. Also, a design example, complete with \sc Matlab code illustrates how the Polynomial Toolbox can be used in the design of residual generators.
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| 20. |
- Nielsen, Lars, 1955-, et al.
(författare)
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Issues in Diagnosis, Supervision, and Safety
- 1996
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Issues concerning diagnosis, supervision and saftey are found in many technologically advanced products. There is now a trend to extend the functionality of diagnosis and supervision systems to handle more advanced situations. This report collects some of the initiatives taking place in research and some of the developments taking place in the industry.
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| 21. |
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| 22. |
- Nyberg, Mattias, 1970-
(författare)
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Model Based Fault Diagnosis : Methods, Theory, and Automotive Engine Applications
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Model based fault diagnosis is to perform fault diagnosis by means of models. An important question is how to use the models to construct a diagnosis system. To develop a general theory for this, useful in real applications, is the topic of the first part of this thesis. The second part deals with design of linear residual generators and fault detectability analysis.A general framework, for describing and analyzing diagnosis problems, is proposed. Within this framework a diagnosis method structured hypothesis tests is developed. It is based on general hypothesis testing and the task of diagnosis is transferred to the task of validating a set of different models with respect to the measured data. The procedure of deriving the diagnosis statement, i.e. the output from the diagnosis system, is in this method formalized and described by logic.Arbitrary types of faults, including multiple faults, can be handled, both in the general framework and also in the method structured hypothesis tests. It is shown how well known methods for fault diagnosis fit into the general framework. Common methods such as residual generation, parameter estimation, and statistically based methods can be seen as different methods to generate test quantities within the method structured hypothesis tests.Based on the general framework, a method for evaluating and comparing diagnosis systems is developed. Concepts from decision theory and statistics are used to define a performance measure, which reflects the probability of e.g. false alarm and missed detection. Based on the evaluation method, a procedure for automatic design of diagnosis systems is developed.Within the framework, diagnosis systems for the air-intake system of automotive engines are designed. In one case, the procedure for automatic design is used. Also the methods for evaluation of diagnosis systems are applied. The whole design chain is described, including the modeling of the engine. All diagnosis systems are validated in experiments using data from a real engine. This application highlights the strengths of the method structured hypothesis tests, since a large variety of different faults need to be diagnosed. To the authors knowledge, the same problem can not be solved using previous methods.In the second part of the thesis, linear residual generation is investigated by using a notion of polynomial bases for residual generators. It is shown that the order of such a basis doesn't need to be larger than the system order. Fault detectability, seen as a system property, is investigated. New criterions for fault detectability, and especially strong fault detectability, are given.A new design method, the minimal polynomial basis approach, is presented. This method is capable of generating all residual generators, explicitly those of minimal order. Since the method is based on established theory for polynomial matrices, standard numerically efficient design tools are available. Also, the link to the well known Chow-Willsky scheme is investigated. It is concluded that in its original version, it has not the nice properties of the minimal polynomial basis approach.
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| 23. |
- Nyberg, Mattias, 1970-, et al.
(författare)
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Parity Functions as Universal Residual Generators and Tool for Fault Detectability Analysis
- 1997
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Konferensbidrag (refereegranskat)abstract
- The Chow-Willsky scheme is a design method for residual generation. Here an extension to the Chow-Willsky scheme, called the ULPE scheme, is presented. The ULPE scheme is shown to be able to generate all possible residual generators for both discrete and continuous linear systems. It is also shown that previous extensions to the Chow-Willsky scheme do not have this capability. Two new straightforward conditions on the process for fault detectability and strong fault detectability are presented. A general condition for strong fault detectability has not been presented elsewhere. It is shown that fault detectability and strong fault detectability can be seen as system properties rather than properties of the residual generator.
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| 24. |
- Nyberg, Mattias, 1970-, et al.
(författare)
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Residual generation for fault diagnosis of systems described by linear differential-algebraic equations
- 2006
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Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 51:12, s. 1995-2000
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Tidskriftsartikel (refereegranskat)abstract
- Linear residual generation for differential-algebraic equation (DAE) systems is considered within a polynomial framework where a complete characterization and parameterization of all residual generators is presented. Further, a condition for fault detectability in DAE systems is given. Based on the characterization of all residual generators, a design strategy for residual generators for DAE systems is presented. The design strategy guarantees that the resulting residual generator is sensitive to all the detectable faults and also that the residual generator is of lowest possible order. In all results derived, no assumption about observability or controllability is needed. In particular, special care has been devoted to assure the lowest-order property also for non-controllable systems. © 2006 IEEE.
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| 25. |
- Nyberg, Mattias, 1970-
(författare)
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The Polybox Example using the Framework of Structured Hypothesis Tests
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The POLYBOX example is a standard example within the AI-field of model-based diagnosis research. Here, this example is discussed in the perspective of structured hypothesis tests (SHT). Even though the SHT framework was primarily developed for handling systems with noise, it has here been shown that it can perform very well in also noise-free systems. In the POLYBOX example, it manage to always give a complete and logically sound diagnosis statement, i.e. a complete and correct list of the possible fault modes. On the contrary, the established FDI framework (i.e. structured residuals) only manage to give a subset of the possible fault modes.
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