Locating Multiple Soft Faults in Wire Networks Using An Alternative DORT Implementation

International audienceDecomposition of the time reversal operator (DORT) was recently applied to the problem of detection and location of soft faults in wire networks and proved effectual when dealing with a single fault, even in the case of complex network configurations. In this paper, the case of location of multiple faults is addressed, first proving that the standard DORT formulation does not allow to take a clear decision about the individual position of each fault. An alternative version of the DORT, based on an updating procedure, is presented and demonstrated to enable accurate and selective location of multiple soft faults. The proposed procedure is also shown to allow estimating the reflection coefficient of each fault, thus giving access to their severity

Imaging Techniques for soft fault detection and location in wiring networks

Les câbles électriques sont partout dans de nombreux domaines où le transfert d'énergie et de l'information est nécessaire pour garantir une bonne performance d'un système. Un jour ou l'autre, un câble dans un réseau va montrer des signes de faiblesse qui conduit à l'apparition de défauts soit francs ou non francs. Malgré le fait que plusieurs méthodes de diagnostic de fil électriques et non-électriques ont été étudiés et mis au point au cours des dernières décennies, les techniques basées réflectométrie ont fourni des résultats efficaces avec des défauts difficiles, mais ont montré moins fiables à chaque fois que des erreurs légères sont traitées.Basé sur un concept radicalement différent, la méthode DORT, développé à l'origine en acoustique a récemment été transposée à la propagation à ondes guidées, par exemple, les réseaux de fils, et montré pour détecter avec précision et localiser les défauts mous simples même dans les configurations de réseau complexes. D'autre part, plusieurs défauts ne peuvent être résolus séparément. Désormais une formulation alternative du DORT basée sur un système de mise à jour est proposée. Notamment, cette nouvelle approche, appelée EDORT, a permis de localiser plusieurs défauts non francs dans différents réseaux de câblage et a permis l'extraction de l'intensité de chaque défaut uniquement. D'autre part, ces méthodes dans le domaine temporel comptent sur la disponibilité de potentiellement importantes largeurs de bande, afin de créer les conditions pour la résolution spatiale. Retournement temporel (TR) classement de signaux multiples, également connu sous le TR-MUSIC, assurée sous-longueur d'onde résolution spatiale des emplacements des défauts tout en travaillant sur une base mono-fréquence. TR-MUSIC a montré une bonne performance dans la localisation unique, ainsi que de multiples défauts non francs dans différentes configurations de réseau. Il a également montré pour permettre la récupération du coefficient de réflexion de chaque défaut séparément.Electrical cables are everywhere in many fields where the transfer of energy and information is necessary to guarantee a good performance of a system. One day or another, a cable in a network will show signs of weakness leading to the appearance of either hard or soft faults. Despite the fact that several electric and non-electric wire diagnosis methods have been studied and developed throughout the last few decades, reflectometrybased techniques have been providing effective results with hard faults, but have shown to be less reliable whenever soft faults are addressed. Based on a radically different concept, the DORT method, originally developed in acoustics was recently transposed to guided-wave propagation, e.g., wire networks, and shown to precisely detect and locate single soft faults even within complex network configurations. On the other hand, multiple faults cannot be resolved separately. Henceforth an alternative formulation of the DORT based on an updating scheme is proposed. Notably, this novel approach, referred to as EDORT, allowed locating multiple soft faults in different wiring networks and enabled extracting the intensity of each fault solely. On the other hand, such time domain methods rely on the availability of potentially large bandwidths, in order to create the conditions for spatial resolution. Time-reversal (TR) multiple signal classification, also known as TR-MUSIC, ensured sub-wavelength spatial resolution of the faults’ locations while working on a single-frequency basis. TR-MUSIC has shown a good performance in locating single as well as multiple soft faults in different network configurations. It has also shown to allow retrieving the reflection coefficient of each fault separately

Techniques d'imagerie pour la détection et la localisation de défauts non francs dans les réseaux de câblage

Electrical cables are everywhere in many fields where the transfer of energy and information is necessary to guarantee a good performance of a system. One day or another, a cable in a network will show signs of weakness leading to the appearance of either hard or soft faults. Despite the fact that several electric and non-electric wire diagnosis methods have been studied and developed throughout the last few decades, reflectometrybased techniques have been providing effective results with hard faults, but have shown to be less reliable whenever soft faults are addressed. Based on a radically different concept, the DORT method, originally developed in acoustics was recently transposed to guided-wave propagation, e.g., wire networks, and shown to precisely detect and locate single soft faults even within complex network configurations. On the other hand, multiple faults cannot be resolved separately. Henceforth an alternative formulation of the DORT based on an updating scheme is proposed. Notably, this novel approach, referred to as EDORT, allowed locating multiple soft faults in different wiring networks and enabled extracting the intensity of each fault solely. On the other hand, such time domain methods rely on the availability of potentially large bandwidths, in order to create the conditions for spatial resolution. Time-reversal (TR) multiple signal classification, also known as TR-MUSIC, ensured sub-wavelength spatial resolution of the faults’ locations while working on a single-frequency basis. TR-MUSIC has shown a good performance in locating single as well as multiple soft faults in different network configurations. It has also shown to allow retrieving the reflection coefficient of each fault separately.Les câbles électriques sont partout dans de nombreux domaines où le transfert d'énergie et de l'information est nécessaire pour garantir une bonne performance d'un système. Un jour ou l'autre, un câble dans un réseau va montrer des signes de faiblesse qui conduit à l'apparition de défauts soit francs ou non francs. Malgré le fait que plusieurs méthodes de diagnostic de fil électriques et non-électriques ont été étudiés et mis au point au cours des dernières décennies, les techniques basées réflectométrie ont fourni des résultats efficaces avec des défauts difficiles, mais ont montré moins fiables à chaque fois que des erreurs légères sont traitées.Basé sur un concept radicalement différent, la méthode DORT, développé à l'origine en acoustique a récemment été transposée à la propagation à ondes guidées, par exemple, les réseaux de fils, et montré pour détecter avec précision et localiser les défauts mous simples même dans les configurations de réseau complexes. D'autre part, plusieurs défauts ne peuvent être résolus séparément. Désormais une formulation alternative du DORT basée sur un système de mise à jour est proposée. Notamment, cette nouvelle approche, appelée EDORT, a permis de localiser plusieurs défauts non francs dans différents réseaux de câblage et a permis l'extraction de l'intensité de chaque défaut uniquement. D'autre part, ces méthodes dans le domaine temporel comptent sur la disponibilité de potentiellement importantes largeurs de bande, afin de créer les conditions pour la résolution spatiale. Retournement temporel (TR) classement de signaux multiples, également connu sous le TR-MUSIC, assurée sous-longueur d'onde résolution spatiale des emplacements des défauts tout en travaillant sur une base mono-fréquence. TR-MUSIC a montré une bonne performance dans la localisation unique, ainsi que de multiples défauts non francs dans différentes configurations de réseau. Il a également montré pour permettre la récupération du coefficient de réflexion de chaque défaut séparément

Multi-Frequency TR-MUSIC Processing to Locate Soft Faults in Cables Subject to Noise

International audienceTime-Reversal multiple signal classification (TR-MUSIC) has recently been shown to be an effective technique to locate multiple soft faults in wire networks, thanks to its sub-millimeter location accuracy. TR-MUSIC processes transmission and reflection data measured at a single frequency into a function of space, the pseudo spectrum, expected to present singularities only at a fault position. At frequencies high enough, the spatial periodicity that comes with the propagation of harmonic signals leads to multiples such singularities, of which only one represents the fault position, while the remaining are ghosts faults. TR-MUSIC was therefore introduced using a single continuous-wave excitation at frequencies low enough to avoid ghosts, an approach suitable only to noiseless configurations. This paper explores the effects of noise on TR-MUSIC fault location by first highlighting its high sensitivity to noise at low frequency. A potentially lower sensitivity is shown to exist at high frequencies, where ghosts positions are found. A multi-frequency processing is introduced, allowing at the same time to solve the ambiguity in the fault position and to effectively control the impact of noise on its location accuracy. The proposed processing is shown to reinstate precise super-resolved estimates of fault locations even for signal-to-noise ratios as low as 5 dB, without requiring to the use of wide-band signals. Index Terms-Fault detection, fault location, soft faults, complex wire networks, additive noise

A Heuristic Approach Applied to Time Reversal MUSIC Method for Soft Fault Location in Noisy Transmission Line Networks

http://piers.org/piers2019Xiamen/International audienceTime-Reversal multiple signal classification (TR-MUSIC) has emerged as a promising technique to locate multiple soft faults in complex wire networks, thanks to its location accuracy and sub-millimeter resolution. The surprising ability to operate using continuous wave excitations even at low frequencies makes its readily adaptable to live wire testing. However, real-life networks are always surrounded by different sources of noise, an issue which is rarely addressed in the domain of fault detection and location. Intrinsically, TR-MUSIC capable of resolving multiple scatterers in open media has shown resolution degrading problems in the presence of perturbations. Accordingly, we will study in this paper the effect noise can bring on the fault location accuracy in different complex wire networks. This will be followed by proposing a heuristic clustering approach which will enable returning good estimates of the fault location at signal to noise ratio (SNR) well below 5 dB

Blind diagnosis of a black-boxed fully-loaded wiring network for configuration structuring and fault monitoring

International audienceAlthough enormous efforts have been exerted to limit the extensive reckoning on wired networks amid nowadays wirefree revolution, dispensing cables is still out of reach. Accordingly, guaranteeing a trustworthy and reliable usage of cables is necessary. Despite the fact that many techniques have been deployed for this sake, several restrictions hindered their proper application. In fact, a prior knowledge of the network's topology, disconnecting loads, and controlled measurement setups are among many other conditions that can greatly affect the performance of monitoring the cable health. On the other hand, the promising non-destructive testing abilities of reflectometry methods emphasized exploring helpful means to bypass the afore-mentioned restrictions. In this paper, we will propose an approach based on the standard reflectometry technique jointly integrated with the graph theory and the particle swarm optimization tool in order locate defects in a fully-loaded unknown-topology transmission line network. Practical experimental results are accomplished to validate the suggested method

A joint reflectometry-optimization algorithm for mapping the topology of an unknown wire network

Conference of 16th IEEE SENSORS Conference, ICSENS 2017 Conference Code:132067International audienceDespite the fact that wireless systems are overwhelming most of nowadays applications, wiring networks are still forming a pivotal anchor in many controls and security units. Thus, ensuring the reliable operation of such networks necessitates investing in techniques dedicated for their protection. A vast majority of such methods rely on the presence of a reference model of the network. In this paper, we propose a nondestructive testing approach based on the tenets of reflectometry methods and genetic algorithms to retrieve the topology and load impedances of unknown embedded complex wiring networks

Locating Faults with High Resolution Using Single-Frequency TR-MUSIC Processing

International audienceTime-Reversal multiple signal classification (TR-MUSIC) is here applied to testing cable networks in order to detect and locate soft faults. TR-MUSIC is shown to provide spatial resolution in the millimeter range while using continuous-wave (CW) test signals, even at frequencies with guided wavelengths much larger than cables length. State of the art time-domain reflectometry (TDR) methods would require bandwidths in the order of hundreds of MHz for a similar performance. As opposed to TDR, TR-MUSIC does not suffer from the ambiguity created by the existence of multiple echoes in cable networks, which can be easily misinterpreted as multiple faults, leading to false alarms. TR-MUSIC is intrinsically adapted to dealing with multiple faults, handing a direct estimate of the number of faults found in a network under test. Furthermore, the detection capabilities of TR-MUSIC are insensitive to the severity of a fault, as faults are not detected based on the intensity of their echoes as done in TDR techniques, but on a sub-space approach mostly dependent on phase patterns. Accurate identification of faults from CW signals points to the possibility of designing simpler test systems, not requiring pulse generators and fast electronics. TR-MUSIC accuracy is demonstrated experimentally for locating both single as well as multiple soft faults in two cable networks. The proposed method also gives access to the reflection coefficient of each fault, thus enabling an estimate of its severity

On the phase analysis of multi-carrier signals for high-precision fault detection by reflectometry

Conference of 16th IEEE SENSORS, ICSENS 2017 ; Conference Date: 30 October 2017 Through 1 November 2017; Conference Code:132067International audienceElectronic systems are becoming always more complex and consequently more subject to defect. For safety, security and integrity reasons, wire diagnosis is crucial. The emerging of sensor networks and connected objects has created the need for embedded and non invasive fault diagnosis solutions. Actual systems rely on multi-carrier reflectometry to locate upcoming defects on wires, though their precision stays within the physical limits of their components, especially the sampling frequency of their analog parts. We propose a new approach combining multi-carrier reflectometry and phase analysis to overcome this limit, in order to improve the precision of the localization of the defects on electrical wires. Based on an FPGA implementation, our novel method and the resulting system has proven a five-times better accuracy than state-of-the-art methods on the same platform