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On-line model-based fault detection and isolation for PEM fuel cell stack systems Rosich, Albert ; ; in Applied Mathematical Modelling (in press) Efficient and reliable operation of Polymer Electrolyte Membrane (PEM) fuel cells are key requirements for their successful commercialization and application. The use of diagnostic techniques enables the ... [more ▼] Efficient and reliable operation of Polymer Electrolyte Membrane (PEM) fuel cells are key requirements for their successful commercialization and application. The use of diagnostic techniques enables the achievement of these requirements. This paper focuses on model-based fault detection and isolation (FDI) for PEM fuel cell stack systems. The work consists in designing and selecting a subset of consistency relations such that a set of predefined faults can be detected and isolated. Despite a nonlinear model of the PEM fuel cell stack system will be used, consistency relations that are easily implemented by a variable back substitution method will be selected. The paper also shows the significance of structural models to solve diagnosis issues in complex systems. [less ▲] Detailed reference viewed: 182 (14 UL)Design and Simulation of a Real-Time Implementable Energy-Efficient Model-Predictive Cruise Controller for Electric Vehicles Schwickart, Tim Klemens ; Voos, Holger ; Minaglou, Jean-Régis et al in Journal of the Franklin Institute (2015), 352(2), 603-625 This paper presents the design of a novel energy-efficient model-predictive cruise controller for electric vehicles as well a simulation model of the longitudinal vehicle dynamics and its energy ... [more ▼] This paper presents the design of a novel energy-efficient model-predictive cruise controller for electric vehicles as well a simulation model of the longitudinal vehicle dynamics and its energy consumption. Both, the controller and the dynamic model are designed to meet the properties of a series-production electric vehicle whose characteristics are identified and verified by measurements. A predictive eco-cruise controller involves the minimisation of a compromise between terms related to driving speed and energy consumption which are in general both described by nonlinear differential equations. Considering the nonlinearities is essential for a proper prediction of the system states over the prediction horizon to achieve the desired energy-saving behaviour. In this work, the vehicle motion equation is reformulated in terms of the kinetic energy of the moving vehicle which leads to a linear differential equation without loss of information. The energy consumption is modeled implicitly by exploiting the special form of the optimisation problem. The reformulations finally lead to a model-predictive control approach with quadratic cost function, linear prediction model and linear constraints that corresponds to a piecewise linear system behaviour and allows a fast real-time implementation with guaranteed convergence. Simulation results of the MPC controller and the simulation model in closed-loop operation finally provide a proof of concept. [less ▲] Detailed reference viewed: 263 (24 UL)A model predictive approach for cyber-attack detection and mitigation in control systems Rosich, Albert ; Voos, Holger ; et al in 52nd IEEE Conference on Decision and Control CDC 2013, Florence, Italy, Dec. 2013 (2013, December 13) The paper presents a new approach for control security. Specifically, cyber-attacks on the controller are investigated by means of optimization techniques in order to determine the worst-case scenario ... [more ▼] The paper presents a new approach for control security. Specifically, cyber-attacks on the controller are investigated by means of optimization techniques in order to determine the worst-case scenario. Then, a novel attack detector based on limit checking is introduced. The particularity of this detector is that no specific controller knowledge is necessary. Hence, the vulnerability of the detector can be reduced since no reconfiguration is required (limited accessibility). Finally, the paper shows that the effect of the attacks on the system can be significantly mitigated by applying proper optimal control laws. [less ▲] Detailed reference viewed: 127 (19 UL)Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms ; ; et al in 2nd International Conference on Control and Fault-Tolerant Systems (2013) In this paper, a new approach for sensor placement in water distribution networks (WDN) is proposed. The sensor placement problem is formulated as an integer optimization problem. The optimization ... [more ▼] In this paper, a new approach for sensor placement in water distribution networks (WDN) is proposed. The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the non-linear integer and large-scale nature of the resulting optimization problem, genetic algorithms (GA) are used as solution approach. To validate the results obtained, they are compared with exhaustive search methods with higher computational cost proving that GA allow to find near-optimal solutions with less computational load. The proposed sensor placement algorithm is combined with a projection-based isolation scheme. However, the proposed methodology does not depend on the isolation method chosen by the user and it could be easily adapted to any other isolation scheme. Experiments on a real network allow to evaluate the performance of such approach. [less ▲] Detailed reference viewed: 80 (10 UL)Optimal Sensor Placement for Leak Location in Water Distribution Networks Using Genetic Algorithms ; ; et al in Sensors (2013), 13(11), 14984-15005 This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization ... [more ▼] This paper proposes a new sensor placement approach for leak location in water distribution networks (WDNs). The sensor placement problem is formulated as an integer optimization problem. The optimization criterion consists in minimizing the number of non-isolable leaks according to the isolability criteria introduced. Because of the large size and non-linear integer nature of the resulting optimization problem, genetic algorithms (GAs) are used as the solution approach. The obtained results are compared with a semi-exhaustive search method with higher computational effort, proving that GA allows one to find near-optimal solutions with less computational load. Moreover, three ways of increasing the robustness of the GA-based sensor placement method have been proposed using a time horizon analysis, a distance-based scoring and considering different leaks sizes. A great advantage of the proposed methodology is that it does not depend on the isolation method chosen by the user, as long as it is based on leak sensitivity analysis. Experiments in two networks allow us to evaluate the performance of the proposed approach. [less ▲] Detailed reference viewed: 76 (6 UL)Model-based Leakage Localization in Drinking Water Distribution Networks using Structured Residuals Rosich, Albert ; in European Control Conference (ECC), 2013 (2013) In this paper, a new model based approach to leakage localization in drinking water networks is proposed based on generating a set of structured residuals. The residual evaluation is based on a numerical ... [more ▼] In this paper, a new model based approach to leakage localization in drinking water networks is proposed based on generating a set of structured residuals. The residual evaluation is based on a numerical method based on an enhanced Newton-Raphson algorithm. The proposed method is suitable for water network systems because the non-linearities of the model make impossible to derive analytical residuals. Furthermore, the computed residuals are designed so that leaks are decoupled, which improves the localization of leaks with respect to other existing methods. Finally, the Hanoi water network benchmark is used to illustrate the results of the proposed approach. [less ▲] Detailed reference viewed: 104 (22 UL)Sensor Placement for Fault Diagnosis Performance Maximization under Budgetary Constraints ; ; Rosich, Albert in 2nd International Conference on Systems and Control (2012) This paper presents a strategy based on fault diagnosability maximization to optimally locate sensors in complex systems. The goal is to characterize and determine a sensor configuration that guarantees a ... [more ▼] This paper presents a strategy based on fault diagnosability maximization to optimally locate sensors in complex systems. The goal is to characterize and determine a sensor configuration that guarantees a maximum degree of diagnosability and does not exceed a maximum sensor configuration cost. The strategy is based on the structural system model. Structural analysis is a powerful tool for dealing with complex nonlinear systems. The proposed approach is successfully applied to a Fuel Cell Stack System. [less ▲] Detailed reference viewed: 50 (9 UL)Sensor Placement for Fault Detection and Isolation based on Structural Models Rosich, Albert in Fault Detection, Supervision and Safety of Technical Processes, Volume# 8 | Part# 1 (2012) This work develops a methodology to solve the sensor placement problem for fault detection and isolation. The proposed methodology is suitable to handle highly non-linear and large scale systems since it ... [more ▼] This work develops a methodology to solve the sensor placement problem for fault detection and isolation. The proposed methodology is suitable to handle highly non-linear and large scale systems since it is based on structural models. Furthermore, causality is assigned in those variable-equation relations that the variable can be computed from the equation in order to guarantee the computability of the unknown variables in the residual generation design. Finally, the developed methodology is applied on an air compressor model. [less ▲] Detailed reference viewed: 58 (9 UL)Model-based Optimal Sensor Placement Approaches to Fuel Cell Stack System Fault Diagnosis ; ; Rosich, Albert in Fault Detection, Supervision and Safety of Technical Processes, Volume# 8 | Part# 1 (2012) The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre-established set of FDI ... [more ▼] The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre-established set of FDI specifications for a given set of faults. This paper recalls three model-based optimal sensor location approaches: an Incremental search, a Heuristic search and a Binary Integer Linear Programming (BILP) formulation. The main contribution of this paper is a comparative study that addresses efficiency, flexibility and other issues. The performance of the approaches is demonstrated by an application to a fuel cell stack system. [less ▲] Detailed reference viewed: 64 (13 UL)Optimal Sensor Placement for Leakage Detection and Isolation in Water Distribution Networks Rosich, Albert ; ; in Fault Detection, Supervision and Safety of Technical Processes, Volume# 8 | Part# 1 (2012) In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural ... [more ▼] In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural models and thus it is suitable to handle non-linear and large scale systems. A drawback of this technique arises when costs are assigned uniformly. A main contribution of this paper is the proposal of an iterative methodology that focuses on identifying essential sensors which ultimately leads to an improvement of the optimal search efficiency. The algorithm presented in this work is successfully applied to a District Metered Area (DMA) in the Barcelona water distribution network. [less ▲] Detailed reference viewed: 65 (6 UL)Sensor Placement for Fault Diagnosis Performance Maximization in Distribution Networks ; ; Rosich, Albert in Control & Automation (MED), 2012 20th Mediterranean Conference on (2012) The success of any diagnosis strategy critically depends on the sensors measuring process variables. This paper presents a strategy based on diagnosability maximization for optimally locating sensors in ... [more ▼] The success of any diagnosis strategy critically depends on the sensors measuring process variables. This paper presents a strategy based on diagnosability maximization for optimally locating sensors in distribution networks. The goal is to characterize and determine the set of sensors that guarantees a maximum degree of diagnosability taking into account a given sensor configuration cardinality constraint. The strategy is based on the structural model of the system under consideration. Structural analysis is a powerful tool for determining diagnosis possibilities and evaluating whether the number and the location of sensors are adequate in order to meet some diagnosis specifications. The proposed approach is successfully applied to leakage detection in a Drinking Water Distribution Network. [less ▲] Detailed reference viewed: 32 (3 UL)Fault Diagnosis Based On Causal Computations Rosich, Albert ; ; et al in IEEE Transactions on Systems, Man & Cybernetics : Part A (2011), 42(2), 371-381 This paper focuses on residual generation for model-based fault diagnosis. Specifically, a methodology to derive residual generators when nonlinear equations are present in the model is developed. A main ... [more ▼] This paper focuses on residual generation for model-based fault diagnosis. Specifically, a methodology to derive residual generators when nonlinear equations are present in the model is developed. A main result is the characterization of computation sequences that are particularly easy to implement as residual generators and that take causal information into account. An efficient algorithm, based on the model structure only, which finds all such computation sequences, is derived. Furthermore, fault detectability and isolability performances depend on the sensor configuration. Therefore, another contribution is an algorithm, also based on the model structure, that places sensors with respect to the class of residual generators that take causal information into account. The algorithms are evaluated on a complex highly nonlinear model of a fuel cell stack system. A number of residual generators that are, by construction, easy to implement are computed and provide full diagnosability performance predicted by the model. [less ▲] Detailed reference viewed: 39 (6 UL)An Optimal Sensor Placement Algorithm taking into account Diagnosability Specifications ; Rosich, Albert ; in Automation Quality and Testing Robotics (AQTR), 2010 IEEE International Conference on (Volume:2 (2010) Suitable installed sensors in a industrial process is a necessary condition for fault diagnosis. Sensor placement for diagnosis purposes is to study which process variables have to be measured to satisfy ... [more ▼] Suitable installed sensors in a industrial process is a necessary condition for fault diagnosis. Sensor placement for diagnosis purposes is to study which process variables have to be measured to satisfy diagnosis specifications (detectability, dis-criminability and diagnosability). This paper presents a method based on the study of the structural model properties and the Dulmage-Mendelsohn decomposition. Due to the use of structural models, the proposed approach can be applied to a wide variety of system (linear, algebraic, dynamics, etc.). Assuming that the cost of placing a sensor for each possible variable is defined, this method finds the minimal cost sensor configuration according to the diagnosability criteria. This method does not require the computation of testable subsystems [less ▲] Detailed reference viewed: 111 (4 UL)Optimal Sensor Placement For Fuel Cell System Diagnosis using BILP Formulation ; ; Rosich, Albert in Control & Automation (MED), 2010 18th Mediterranean Conference on (2010) This paper presents the application of a new methodology for Fault Detection and Isolation (FDI) to a Fuel Cell System. The work is devoted to find an optimal set of sensors for model-based FDI. The ... [more ▼] This paper presents the application of a new methodology for Fault Detection and Isolation (FDI) to a Fuel Cell System. The work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that binary integer linear programming (BILP) is used in the optimization formulation, leading to a reformulation of the detectability and isolability specifications as linear inequality constraints. The approach has been successfully applied to a Fuel Cell System. [less ▲] Detailed reference viewed: 48 (4 UL)Efficient Optimal Sensor Placement for Structural Model Based Diagnosis Rosich, Albert ; ; in 21st Annual Workshop Proceedings (2010) This work aims to study which sensors are required to be installed in a process in order to improve certain fault diagnosis specifications. Especially, the present method is based on structural models ... [more ▼] This work aims to study which sensors are required to be installed in a process in order to improve certain fault diagnosis specifications. Especially, the present method is based on structural models. Thus system models involving a wide variety of equations (e.g. linear, non-linear algebraic, dynamics) can be easy handled. The use of structural models permits to define the diagnosis properties from the Dulmage-Mendelsohn decomposition, avoiding in this way the computation of any minimal redundant subsystem. Furthermore, in the present paper, the cost of the sensor configuration is considered. Therefore, the proposed method attempts to find not all the possible solution but the optimal one. The optimal search is efficiently performed by developing an algorithm based on heuristic rules which, in general, allow to significantly reduce the search. [less ▲] Detailed reference viewed: 88 (5 UL)Fuel Cell System Diagnosis based on a Causal Structural Model Rosich, Albert ; ; in Fault Detection, Supervision and Safety of Technical Processes (2009) In this work, a diagnosis system is developed and applied to a fuel cell stack system. The paper shows the significance of structural models to solve diagnosis issues in large scale systems. The diagnosis ... [more ▼] In this work, a diagnosis system is developed and applied to a fuel cell stack system. The paper shows the significance of structural models to solve diagnosis issues in large scale systems. The diagnosis system based on residual generation by means of the computation of causal MSO sets (Minimal Structural Overdetermined) is capable of detecting and isolating faults in the fuel cell system. [less ▲] Detailed reference viewed: 54 (3 UL)Sensor Placement for Fault Diagnosis Based On Causal Computations Rosich, Albert ; ; et al in Fault Detection, Supervision and Safety of Technical Processes (2009) This work develops a methodology to solve the sensor placement problem for fault detection and isolation. The proposed methodology is suitable to handle highly non-linear and large scale systems since it ... [more ▼] This work develops a methodology to solve the sensor placement problem for fault detection and isolation. The proposed methodology is suitable to handle highly non-linear and large scale systems since it is based on structural models. Furthermore, causality is assigned in those variable-equation relations that the variable can be computed from the equation in order to guarantee the computability of the unknown variables in the residual generation design. Finally, the developed methodology is applied on an air compressor model. [less ▲] Detailed reference viewed: 87 (1 UL)Optimal Sensor Placement for FDI using Binary Integer Linear Programming Rosich, Albert ; ; in 20th International Workshop on Principles of Diagnosis (2009) This work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that linary integer linear programming is used in the optimization problem, leading to a formulation of the ... [more ▼] This work is devoted to find an optimal set of sensors for model-based FDI. The novelty is that linary integer linear programming is used in the optimization problem, leading to a formulation of the detectability and isolability specifications as linear inequality constraints. Furthermore, a very detailed system model is not needed since the methodology handles structural models. The approach has been successfully applied to a two-tank system, as an illustrative example. [less ▲] Detailed reference viewed: 85 (3 UL)Optimal Sensor Placement for Model-Based Fault Detection and Isolation ; ; et al in Decision and Control, 2007 46th IEEE Conference on (2007) The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre- established set of FDI ... [more ▼] The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre- established set of FDI specifications for a given set of faults. The main contribution of this paper is to propose an algorithm for model-based FDI sensor placement based on formulating a mixed integer optimization problem. FDI specifications are translated into constraints of the optimization problem considering that the whole set of ARRs has been generated, under the assumption that all candidate sensors are installed. To show the effectiveness of this approach, an application based on a two-tanks system is proposed. [less ▲] Detailed reference viewed: 38 (1 UL)Efficient Optimal Sensor Placement for Model-Based FDI using an Incremental Algorithm Rosich, Albert ; ; et al in Decision and Control, 2007 46th IEEE Conference on (2007) The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre-established set of FDI ... [more ▼] The problem of optimal sensor placement for FDI consists in determining the set of sensors that minimizes a pre-defined cost function satisfying at the same time a pre-established set of FDI specifications for a given set of faults. Existing approaches are mainly based on formulating an optimization problem once the sets of all possible ARRs has been generated, considering all possible candidate sensors installed. However, the associated computational complexity is exponential with the number of possible sensors. The main goal of this paper is to propose an incremental algorithm for FDI sensor placement that tries to avoid the computational burden. To show the effectiveness of this approach, an application based on a fuel-cell system is proposed. [less ▲] Detailed reference viewed: 31 (3 UL) |
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