Authors: Roberts, Clive; Goodall, R.M.

Abstract: The paper provides an overview related to condition monitoring on railways, starting with a summary of key political and social trends for railways worldwide leading on to an identification of the parts of the railway for which efficient and effective monitoring is becoming an increasingly important issue. Railway condition monitoring has become a "hot topic" within the last 5 years in particular, although in the early days enormous amounts of data were collected without a proper understanding of how to extract useful knowledge from the data and how business processes needed to be adapted to take advantage of the monitoring information. Examples from within the railway industry of current good practice and appropriate application of advanced techniques are used to highlight developments that are currently being exploited. Some of the current research work on monitoring that has been undertaken by the authors and their colleagues will be used to illustrate the kind of advanced techniques that may become commonplace on railways in the future. Overall the paper reveals the principal trends for monitoring in railways, the associated research challenges and a future vision for monitoring systems and technology applied to railways.

Keywords: Other applications

Identifier: 10.3182/20090630-4-ES-2003.00123

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Gelso, Esteban R.; Blanke, Mogens

Abstract: Isolability of faults is a key issue in fault diagnosis whether the aim is maintenance or active fault-tolerant control. It is often encountered that while faults are detectable, they are only group-wise isolable from a usual diagnostic point of view. However, active injection of test signals on system inputs can considerably enhance fault isolability. This paper investigates this possibility of active fault isolation from a structural point of view. While such extension of the structural analysis approach was suggested earlier, algorithms and case studies were needed to explore this theory. The paper develops algorithms for investigation of the possibilities of active structural isolation and it offers illustrative examples and a larger case study to explore the properties of active structural isolability ideas.

Keywords: Structural analysis

Identifier: 10.3182/20090630-4-ES-2003.00099

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Aaslund, Jan; Frisk, Erik

Abstract: Structural analysis is a standard tool to identify submodels that can be used to design model based diagnostic tests. Structural approaches typically operate on models described by a set of equations. This work extends such methods to be able to handle models with constraints, e.g. inequality constraints on state variables. The objective is to improve isolability properties of a diagnosis system by extending the class of redundancy relations. An algorithm is developed that identifies which are the constraints and equations that can be used together to derive a new test that can not be found using previous approaches.

Keywords: Structural analysis

Identifier: 10.3182/20090630-4-ES-2003.00064

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Saeed, Kashif; Mechbal, Nazih; Coffignal, Gerard; Vergé, Michel

Abstract: In this paper, an Artificial Neural Network (ANN) based approach using a new non-parametric residual is presented for damage diagnosis. The residual is associated with Observability null-space of the system and is generated by using a parity matrix obtained from covariance driven output-only Subspace Identification (SubID) algorithm. Training of ANN is established using residuals generated from Finite Element (FE) model of the structure under consideration for different defect cases. This trained ANN is in turn used to identify the predefined defect types, in semi-real time, on the actual structure. The proposed methodology is applied to an active composite beam structure and its effectiveness to identify damage is studied by testing a trained ANN with data obtained from both simulation and experimentation. Promising results were obtained showing that, it was possible to distinguish between healthy and damaged states with good accuracy and repeatability.

Keywords: Neuro-fuzzy methods; Signal and identification-based methods; Structural analysis

Identifier: 10.3182/20090630-4-ES-2003.00025

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Yang, Quan; Aitouche, Abdel; Ould Bouamama, Belkacem

Abstract: The fuel cell stack system (FCSS) is a complex system because of coupling of several energies. Use of bond graph tool as a multidisciplinary approach is well suited for modeling of such process. The innovative interest in the presented paper is the use of obtained bond graph model not only for simulation but for monitorability (ability to detect and isolate faults) of the FCSS because of structural and causal properties of bond graph model with no need for any numerical calculation. Based on the formal dynamic bond graph model of the fuel cell and it’s environment (including chemical, electrochemical, electrical and hydraulic phenomena) and it’s instrumentation architecture, it will be shown (before industrial design) which faults can be detected and or isolated and how to make them mentionable adding additional sensors. Copyright © 2009 IFAC.

Keywords: Structural analysis; Chemical applications; Power systems applications

Identifier: 10.3182/20090630-4-ES-2003.00121

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Henry, David; Falcoz, Alexandre; Zolghadri, Ali

Abstract: In this paper, a method is presented to design robust fault detection and isolation filters for Linear Parameter Varying (LPV) systems modeled in a Linear Fractional Representation (LFR) fashion. It consists in designing an optimal FDI filter that minimizes the influence of unknown inputs on the residuals, in the Hinfty-norm sense and simultaneously maximizes fault sensitivity performance, in the H- index sense for LPV systems. The design problem is formulated so that all free parameters are optimized via Linear Matrix Inequality techniques. Computational aspects are discussed and it is shown that the proposed solution is structurally well-defined. An illustrative example demonstrates the potential of the proposed method.

Keywords: Sensor and actuator faults; Linear and robust methods

Identifier: 10.3182/20090630-4-ES-2003.00070

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Dong, Jianfei; Kulcsar, Balazs; Verhaegen, Michel

Abstract: This paper presents a new Fault detection and Identification approach Connected to Subspace Identification (FICSI) for a special class of nonlinear system casted to Linear but Parametrically Varying (LPV) form. The model based algorithm utilizes the specific nonlinear nature of the LPV system along the past horizon to construct the output predictor. Similar with its LTI counterpart in a companion paper ([Dong and Verhaegen (2008)]), the FICSI-LPV avoids projecting the residual vector onto the parity space of the extended observability matrix, and hence produces residuals more sensitive to faults than the parity space approach (PSA) for LPV systems does. Asymptotically unbiased condition and algorithm are also proposed for fault estimation. The difference of FICSI from the existing fault detection and estimation approaches based on PSA or moving horizon estimation (MHE) can also be attributed to the fact that FICSI does not require an LPV state space model, but a sequence of Markov parameters mapping the I/O measurements and the scheduling parameters to the residual, which can be estimated in closed-loop.

Keywords: Signal and identification-based methods; Nonlinear methods; Statistical methods

Identifier: 10.3182/20090630-4-ES-2003.00056

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Dong, Jianfei; Verhaegen, Michel

Abstract: This paper presents a new Fault detection and Identification approach Connected to Subspace Identification (FICSI) for LTI systems with additive faults. FICSI parameterizes the influence of initial states on residuals by past I/O measurements, and hence avoids projecting a residual vector onto the left null space of the extended observability matrix. It is proved that FICSI produces residuals more sensitive to faults than the classic parity space approach (PSA) does. Another novelty of this contribution is the unbiased fault estimation algorithm developed in the framework of FICSI, which is not possible in PSA without restricting the nature of faults. The difference of FICSI from the existing fault detection and estimation approaches based on PSA or moving window estimation (MHE) can also be attributed to the fact that FICSI does not require a state space model, but a sequence of Markov parameters mapping the I/O measurements to the residual, which can be estimated in closed-loop.

Keywords: Signal and identification-based methods; Sensor and actuator faults; Statistical methods

Identifier: 10.3182/20090630-4-ES-2003.00055

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Naik, Amol; Ding, Steven X.; Yin, Shen

Abstract: A subspace identification technique based design of observer is developed in this paper. In recent attempts a subspace algorithm to identify state space matrices for LTI system with nonlinearity on the output side, or the so called Wiener systems. The results were based on Bussgang's theorem on crosscorrelation functions of amplitude distorted Gaussian signals. We have combined these two important results in order to develop an observer based fault detection system that is identified directly from the test data generated by nonlinear dynamic systems.

Keywords: Nonlinear methods; Statistical methods; Sensor and actuator faults

Identifier: 10.3182/20090630-4-ES-2003.00053

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Codas, Andrés; Ordonez, Bernardo; Moreno, Ubirajara F.

Abstract: In this paper a framework proposal is presented to the fault detection and isolation system based on principal component analysis for sucker-rod pumping systems using bottom hole pressure and others measurements. The proposed algorithm use signals frequency attributes to generate faults signatures. Hotelling's $T^2$ index and the square prediction error are used to compare process online samples with the signatures. The results were obtained using a sucker-rod pump simulated model.

Keywords: PCA-based methods; Statistical methods

Identifier: 10.3182/20090630-4-ES-2003.00170

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: None

Abstract:

Keywords:

Identifier: 10.3182/20090630-4-ES-2003.90003

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Quevedo, Joseba; Puig, Vicenc; Escobet, Teresa; Nejjari, Fatiha; Sarrate, Ramon; Trave-Massuyes, Louise

Abstract: This paper discusses the use of interval models (LTI models with interval parameters) to represent the dynamics of complex systems in fault detection. Fault detection methods using interval models, such as interval observers and parity equations, will be reviewed and compared. Tools used to implement such algorithms will also be presented. Finally, an overview of the real domain application of these methods and their experimental performance will end the paper.

Keywords: Linear and robust methods

Identifier: 10.3182/20090630-4-ES-2003.00185

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Alcala, Carlos F.; Qin, S. Joe

Abstract: Several diagnosis methods have been proposed for statistical process monitoring. They have been developed from different backgrounds and considerations. In this paper, five existing diagnosis methods are analyzed and compared. It is shown that these methods can be unified into three more general methods, making the original diagnosis methods special cases of the general methods. An analysis of the diagnosability of the general methods shows that some diagnosis methods guarantee correct diagnosis for simple sensor faults with large magnitudes, while others do not. For the case of sensor faults with modest fault magnitudes, a Monte Carlo simulation is used to compare the performance of the diagnosis methods.

Keywords: PCA-based methods; Sensor and actuator faults; Statistical methods

Identifier: 10.3182/20090630-4-ES-2003.00166

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Odgaard, Peter Fogh; Stoustrup, Jakob

Abstract: In order to improve reliability of wind turbines, it is important to detect faults in the turbine as fast as possible to handle them in an optimal way. An important component in modern wind turbines is the converter, which for a wind turbine control point-of-view normally provides the torque acting on the wind turbine generator, as well as measurement of this torque. In this paper an unknown input observer is presented to estimate these faults in the converter and isolate them either to be an actuator fault or a sensor fault. The unknown input observer is used since the speed of wind acting on the wind turbine is assumed unknown, since measurement of it is influenced by the turbulence around the rotor plane. A detection scheme is formed based on these fault estimates. A detail simulation model is used to simulate a wind turbine in which both types of faults are present during the simulation. The detection scheme detects and isolates both faults with in 2 samples of its beginning.

Keywords: Power systems applications; Linear and robust methods; Sensor and actuator faults

Identifier: 10.3182/20090630-4-ES-2003.00027

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Meskin, Nader; Khorasani, Khashayar

Abstract: This paper introduces the notion of unobservability subspaces for continuous-time Markovian Jump System (MJS) with irreducible Markov process. First a geometric property related to the unobservable subspace of a Markovian jump system is presented. A new approach for determining the conditions for weak-observability of MJS systems is then developed. The concept of an unobservability subspace is presented and an algorithm for obtaining it is described. The necessary and sufficient conditions for solvability of the fundamental problem of residual generation (FPRG) for MJS systems are derived by utilizing our introduced unobservability subspaces.

Keywords: Discrete-event and hybrid systems; Networked systems; Linear and robust methods

Identifier: 10.3182/20090630-4-ES-2003.00157

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Hu, Zaijun

Abstract: The development of the functional safety requires safety analysis to verify the safety concepts and deliver the sufficient safety evidences. HAZOP is one of the widely-used safety analysis methods. However the effort of using HAZOP enormously increases with growing complexity of a system. Thus an efficient management of the effort without losing necessary detail becomes a key to successful use of HAZOP. In this paper we will present a novel approach that uses the viewpoint concept recommended by IEEE-1471 to simplify and structure the software failure analysis based on HAZOP. Each viewpoint deals with a set of failures by providing a failure pattern, appropriate documentation approaches, and typical failure control measures in such a way that the effort for HAZOP analysis is controlled to an acceptable range. In this paper we are going to present the key concept and the necessary discussion

Keywords: Fault-tolerant control; Dependability; Structural analysis

Identifier: 10.3182/20090630-4-ES-2003.00248

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Stockmann, Markus; Haber, Robert; Schmitz, Ulrich

Abstract: Static friction (stiction) in control valves is an often unrecognized problem which can lead to oscillating process variables. Therefore it is important to detect stiction at an early stage as the reason for oscillation. This work presents a new and robust method which uses the pattern recognition with principal component analysis for stiction detection.

Keywords: Sensor and actuator faults; PCA-based methods; Statistical methods

Identifier: 10.3182/20090630-4-ES-2003.00234

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Nieto, Juan Pablo; Garza-Castañón, Luis; Rabhi, Abdelhamid; El Hajjaji, Ahmed; Morales-Menendez, Ruben

Abstract: A new fault detection and diagnosis approach to deal with noisy measurements and correlated variables is presented. Using Auto-Associative Neural Networks (AANN) the correlation of the variables is learned from normal operating conditions data. Then, residuals can be computed with this AANN model. By comparing residuals against normal operating conditions thresholds, faults can be detected (and sometimes diagnosed) using a Non-Linear Principal Component Analysis. For noisy variables were previous procedure fails, a second sequential step based on several Adaptive Neuro-Fuzzy Inference Systems (ANFIS) is needed. The performance of the approach was validated with a vehicle model. Early results are promising.

Keywords: Neuro-fuzzy methods; Sensor and actuator faults; Automotive applications

Identifier: 10.3182/20090630-4-ES-2003.00178

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: None

Abstract:

Keywords:

Identifier: 10.3182/20090630-4-ES-2003.90002

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Chihaia, Cristian I.; Bredtmann, Oliver; Goldschmidt, Eberhard; Li, Wei; Ding, Steven X.; Czylwik, Andreas

Abstract: WiNC is an experimentation platform for Wireless Networked Control, built with off-the-shelf hardware and open source software. The platform is composed essentially of an application, a driver and a protocol stack optimized for industrial wireless communication. The protocol stack integrates a simplified addressing scheme with a custom packet structure and robust channel coding techniques, thus ensuring deterministic transmission times. The application integrates the communication functionality of organizing the network access by use of a schedule based on timeslots and tailored to the needs of the control system. It implements several control-specific functionalities including fault diagnosis and monitoring.

Keywords: Networked systems; Fault-tolerant control; Other applications

Identifier: 10.3182/20090630-4-ES-2003.00164

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009

Authors: Tharrault, Yvon; Mourot, Gilles; Ragot, Jose

Abstract: Principal component analysis (PCA) is a powerful fault detection and isolation method. However, the classical PCA which is based on the estimation of the sample mean and variance-covariance matrix of the data is very sensitive to outliers in the training data set. Usually robust principal component analysis was applied to remove the effect of outliers on the PCA model. In this paper, a fast two-step algorithm is proposed. First, the objective was to find a robust PCA. Hence a scale-M estimator is computed using an iterative re-weighted least squares (IRWLS) procedure. This algorithm is initialized from a nearly robust variance-covariance estimate which tends to emphasize the contribution of close observations in comparison with distant observations (outliers). Second, structured residuals are used for multiple fault detection and isolation. These structured residuals are based on the reconstruction principle and the existence condition of such residuals is used to determine the detectable faults and the isolable faults. The proposed scheme avoids the combinatorial explosion of faulty scenarios related to multiple faults to consider. Then, this procedure is successfully applied for sensor fault detection and isolation of the hydraulic part of an activated sludge wastewater treatment plant (WWTP).

Keywords: PCA-based methods; Sensor and actuator faults; Other applications

Identifier: 10.3182/20090630-4-ES-2003.00218

Conference: 7th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes

Location: Sants Hotel, Spain

Start Date: Tue Jun 30 2009 - End Date: Fri Jul 03 2009