Sistemes informàtics en temps real

2010/201

Real time diagnosis for a large gas turbine based on a deep model of the controller

The ESPRIT project 6862 TIGER addresses the development of a real-time knowledge based diagnosis system for two gas turbines: a large scale industrial gas turbine and an auxiliary power unit for aviation. The project will combine the qualitative model based with the rule based diagnosis approach. This paper describes the rule based approach taken in the development of a real-time diagnostic system for a large scale gas turbine. Deep models will be automatically extracted from the deterministic knowledge embedded within the controller ladder logic diagrams. Heuristic knowledge will be extracted from the domain expert and engineering manuals.Peer ReviewedPostprint (published version

Health-aware control of an octorotor UAV system based on actuator reliability

A major goal in modern flight control systems is the need of improving the reliability. This work presents a reliable control approach of an octorotor UAV that allows distributing the control effort among the actuators using health actuator information. The octorotor is an over-actuated system where the redundancy of the actuators allows the redistribution of the control effort among the existing actuators according to a given control strategy. The priority is given to each actuator according to the capabilities and reliability of this actuatorPeer ReviewedPostprint (author's final draft

Clustering techniques applied to sensor placement for leak detection and location in water distribution networks

This work presents an optimization strategy that maximizes the leak locatability performance of water distribution networks (WDN). The goal is to characterize and determine a sensor configuration that guarantees a maximum degree of locatability while the sensor configuration cost satisfies a budgetary constraint. The method is based on pressure sensitivity matrix analysis and an exhaustive search strategy. In order to reduce the size and the complexity of the problem the present work proposes to combine this methodology with clustering techniques. The strategy developed in this work is successfully applied to determine the optimal set of pressure sensors that should be installed in a district metered area (DMA) in the Barcelona WDN.Peer ReviewedPostprint (published version

System reliability upper bound assessment for health-aware control of complex systems

Postprint (published version

Hybrid Automaton Incremental Construction for Online Diagnosis

This paper proposes a method to track the system mode and diagnose a hybrid system without building an entire diagnoser off-line. The method is supported by a hybrid automaton model that represents the hybrid system continuous and discrete behavioral dynamics. Diagnosis is performed by interpreting the events and measurements issued by the physical system directly on the hybrid automaton model. This interpretation leads to building the useful parts of the diagnoser incrementally, developing only the branches that are required to explain the occurrence of the incoming events. The resulting diagnoser adapts to the system operational life and is much less demanding in terms of memory storage. The proposed framework subsumes previous works in that it copes with both structural and non-structural faults. The method is validated on an application case study based on the sewer network of the Barcelona city.Peer ReviewedPostprint (author’s final draft

A recursive LMI-based algorithm for efficient vertex reduction in LPV systems

This paper proposes a new algorithm to reduce the number of gains of a polytopic LPV controller considering generic tuples of vertices, for which a common controller gain can be used. The use of Frobenius norm and the inclusion of the input matrix in the LMIs perturbation matrix allows decreasing the conservativeness to select vertices which are combinable, with respect to a previous approach based on Gershgorin circles. A combinability metric that can be applied to an arbitrary partition of the set of vertices is defined. Then, a recursive algorithm finds a lesser-fragmented combinable partition at each iteration by combining together two elements of a partition. The algorithm aims at finding combinable partitions with minimal cardinality in fewer attempts, always preserving the original control performance specifications. The proposed method is validated using numerical examples, a twin rotor MIMO system and a two-link robotic manipulator.This work has been co-financed by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project SCAV (ref. MINECO DPI2017-88403-R), by the European Regional Development Fund of the European Union in the framework of the ERDF Operational Program of Catalonia 2014-2020 (ref. 001-P-001643 Looming Factory) and by the DGR of Generalitat de Catalunya (SAC group ref. 2017/SGR/482).Peer ReviewedPostprint (author's final draft

A methodology for building a fault diagnoser for hybrid systems

In this paper, a design methodology for building diagnosers for hybrid systems is proposed. The design methodology uses as a starting point a hybrid automaton model to represent the hybrid system behaviour by means of the interaction of continuous dynamics and discrete events. Then, a hybrid fault diagnoser is designed using the methodology described in this paper and implemented by means of a discrete event system which carries out the mode recognition and diagnostic tasks, both based on residuals generated using models. Both tasks interact each other since the diagnosis module adapts according to the current mode of the hybrid system. The mode recognition task involves detecting and identifying the mode change by determining the set of residuals that are consistent with the current mode of the hybrid system. On the other hand, the diagnostic task involves detecting and isolating faults by identifying the fault that can explain the set of residuals that are inconsistent. A section of the Barcelona sewer network is used as application case study to illustrate the proposed fault diagnosis for hybrid systems.Peer ReviewedPostprint (author’s final draft

Fault detection and isolation in critical infrastructure systems

Critical infrastructure systems (CIS) are complex large-scale systems which in turn require highly sophisticated supervisory control systems to ensure that high performance can be achieved and maintained under adverse conditions. The global CIS Real-Time Control (RTC) need of operating in adverse conditions involves, with a high probability, sensor and actuator malfunctions (faults). This problem calls for the use of an on-line Fault Detection and Isolation (FDI) system able to detect such faults. This paper proposes a FDI mechanism that extends the classical Boolean fault signature matrix concept taking into account several fault signal properties to isolate faults in CIS. To exemplify the proposed FDI scheme in CIS, the Barcelona drinking water network is used as a case study.Preprin

Health-aware and fault-tolerant control of an octorotor UAV system based on actuator reliability

A major goal in modern flight control systems is the need for improving reliability. This work presents a health-aware and fault-tolerant control approach for an octorotor UAV that allows distributing the control effort among the available actuators based on their health information. However, it is worth mentioning that, in the case of actuator fault occurrence, a reliability improvement can come into conflict with UAV controllability. Therefore, system reliability sensitivity is redefined and modified to prevent uncontrollable situations during the UAV’s mission. The priority given to each actuator is related to its importance in system reliability. Moreover, the proposed approach can reconfigure the controller to compensate actuator faults and improve the overall system reliability or delay maintenance tasks.Peer ReviewedPostprint (published version