A Bayesian network for diagnosis of networked mobile robots

International audienceThe network of communicating mobile vehicles is a subclass of Wireless Networked Control Systems (WNCS) characterized by wireless communications and mobile nodes. The integration of the wireless network into control loop, given the stochastic aspects of wireless communication and mobility of its communicating entities, can lead to problems that affect system performances. In other words, the system quality of control QoC depends on the wireless network quality of service QoS state. A diagnosis method is essential to monitor, diagnose and maintain the system in an operational state. The present paper proposes a modular multi-layer Bayesian network model for diagnosis taking into account the network failures. Results regarding the system performance are presented to illustrate the relevance of the developed Bayesian Network BN to decisions making in order to lead the system to its final goal

Diagnostic des Systèmes Mobiles Communicants

International audienceLes systèmes commandés en réseau, comme les robots mobiles communicant avec une station distante, sont une nouvelle génération de systèmes distribués où la communication entre les actionneurs, les capteurs et le contrôleur est assurée par un réseau de communication. Mais l'intégration du réseau dans la boucle de commande engendre des problèmes au niveau de la performance du système d'où la nécessité d'avoir une méthode de diagnostic et de prise de décision, pour localiser les défaillances. Ce papier présente une méthode de diagnostic utilisant l'approche bayésienne

A generic simulation model to assess the performance of sterilization services in health establishments

International audienceThe work presented here is with a view to improving performance of sterilization services in hospitals. We carried out a survey in a large number of health establishments in the Rhône-Alpes region in France. Based on the results of this survey and a detailed study of a specific service, we have built a generic model. The generic nature of the model relies on a common structure with a high level of detail. This model can be used to improve the performance of a specific sterilization service and / or to dimension its resources. It can also serve for quantitative comparison of performance indicators of various sterilization services

Diagnosis architecture reconfiguration for a networked mobile robot

International audienceWireless networked robots are mobile systems communicating to a control station via a wireless network. These robots move in a distributed infrastructure while receiving orders from control stations to reach their target. A distributed and collaborative diagnosis architecture is a good solution to monitor and diagnose the different components behavior of such distributed system due to the unreliability of wireless networks. Modular Bayesian Network (MBN), as a distributed Bayesian Network, can manage causal uncertain factors (stochastic failures dependencies) and infer information coming from different environments and from devices having memory and calculation limitations. MBN was proposed in our previous work for distributed and collaborative diagnosis. However, the robots can receive orders to switch to autonomous operating mode or to a good performing network (a new control station) to avoid system performance degradation. The robot is no more connected to the station of origin. The diagnosis strategy must consequently be updated. This paper proposes a procedure to reconfigure the diagnosis architecture and the MBN when the mobile robot changes its operating mode i.e, switching from embedded controller to distant controller

Application de techniques de synthèse en ingénierie d'automatisation

National audienceLes techniques de synthèse de la commande proposent des algorithmes permettant de définir automatiquement un modèle de contrôle et de commande, à partir de modèles formels de la dynamique d'un procédé à commander et des objectifs comportementaux qui lui sont assignés. L'utilisation de ces techniques en ingénierie d'automatisation requiert la définition d'un cadre méthodologique permettant de couvrir les phases amont et avale à la synthèse, en particulier, la phase de modélisation de processus industriels complexes et la phase d'implantation du superviseur synthétisé sur une architecture de commande industrielle. L'objectif de ce papier est de démontrer la faisabilité d'une approche méthodologique, qui intègre les techniques de synthèse, basée sur la réutilisation de modules fonctionnels d'automatisation. Son intérêt réside dans la structuration des modèles du procédé et des spécifications comportementales, ce qui constitue une aide méthodologique à la modélisation de systèmes complexes, mais également dans la modularité des superviseurs synthétisés, ce qui facilite leur implantation dans des langages de programmation à base de blocs fonctionnels tels que ceux de la norme IEC 61131-3

A pragmatic approach for modular control synthesis and implementation

ISSN 0020-7543International audienceWithin the framework of Supervisory Control Theory, synthesis algorithms enable automatic generation of control rules from behavioural models of the process to be controlled and of goals to be achieved. This paper talks about a pragmatic use of these algorithms within an automation engineering context and focuses on two key issues: process and goals modelling and supervisory controller implementation. In this way, the approach presented in this paper combines the synthesis techniques and algorithms with an object-oriented automation method that supplies guidelines for the analysis, the design and the implementation of a modular control system. This pragmatic approach is applied to the synthesis and implementation of the control of an assembly station. It highlights the difficulties of the modelling step and its great influence on the synthesis result itself but also demonstrates the feasibility of our synthesis approach through a successful implementation in conformance with the IEC 61131-3 standard

Distributed to Embedded Bayesian Network for Diagnosis of a Networked Robot

International audienceMobile networked robots are distributed systems controlled by a distant station i.e, the controller is implemented on a control station. The main mission of the mobile robot is reaching a target position starting from an initial one while receiving the instructions from the control station via a wireless network. The wireless network is characterized by a stochastic behavior and is sensitive to perturbations. The unreliability of wireless networks does not guarantee data transmission between system components (the robot and the station) which can cause system performance degradation. A distributed Bayesian Network (BN) was proposed in previous work to monitor and diagnose the system performance and to model causal uncertainties between failures. The developed BN is a modular Bayesian Network (MBN) which is composed of three Bayesian modules shared between the robot and the control station. In the case of system performance degradation because of a bad network state, the robot switches to embedded controller implemented on-board (autonomous behavior). The distributed diagnosis architecture must be updated and the diagnosis tool becomes embedded on the robot. A procedure of BNs assembly is described in this work in order to implement one monolithic BN on-board. The obtained monolithic BN is the result of combining two Bayesian modules from the modular Bayesian Network: the control and the operative Bayesian modules

Wireless Network Performance Evaluation for Networked Robots

International audience—The integration of the wireless network into the control loop of Networked Control Systems NCSs, given the stochastic behavior of wireless communication, can degrade the system performance i.e, its Quality of Control (QoC). It is necessary to study the implications of the communication constraints because control systems need a perfect communication medium. The performance of wireless network and its Quality of Service (QoS) must thus be analyzed in order to guarantee a good QoC. The present paper proposes an analysis of QoS performance metrics for networked systems (networked robots) using an analytic model based on Markov chain theory. The Markov model describes the IEEE 802.11 Distributed Coordination Function (DCF) for periodic round trip traffic of Wireless Networked Control System (WNCS)

Etude et amélioration de l'organisation de la production de dispositifs médicaux stériles

Dans les établissements de santé, la stérilisation des dispositifs médicaux occupe une place primordiale dans la lutte contre l'infection. On appelle dispositif médical un instrument de chirurgie ou d'exploration utilisé lors d'une intervention ou d'un examen. Dans cette thèse nous étudions et proposons des améliorations de l'organisation de la production de dispositifs médicaux stériles en appliquant au milieu hospitalier des méthodes habituellement utilisées pour évaluer et améliorer les performances de systèmes de production industriels. Nous avons construit un modèle de simulation spécifique représentant le service de stérilisation du Centre Hospitalier Privé Saint Martin de Caen. Nous montrons les améliorations que nous avons pu obtenir en modifiant certains points de l'organisation. Par la suite nous avons cherché à dégager les spécificités des services de stérilisation de plusieurs établissements hospitaliers, dans le but d'effectuer une comparaison des différents types d'organisation et d'identifier les services les plus performants. Cette comparaison, réalisée à partir de données issues d'une enquête menée auprès d'établissements de la région Rhône-Alpes, repose sur des ratios de comparaison, sur la méthode DEA (Data Envelopment Analysis) et sur un modèle générique de simulation que nous avons élaboré. Dans cette thèse, nous proposons également des pistes pour analyser un service de stérilisation générique en utilisant des méthodes analytiques stochastiques. Nous commençons par dresser un état de l'art sur l'utilisation de modèles stochastiques analytiques pour l'analyse de systèmes de production de soins, puis nous étudions la possibilité d'utiliser une méthode analytique pour analyser notre modèle générique d'un service de stérilisation. Une modélisation par réseau de files d'attente du modèle générique est enfin présentée.In health facilities, the sterilization of medical devices plays a key role in the fight against infections. A medical device is a surgical instrument or an exploration instrument used in operations or examinations. In this thesis we study and propose some improvements of the production organization of medical devices by applying methods commonly used to evaluate and improve the performance of industrial production systems. We elaborated a specific simulation model representing the sterilization service of Private Hospital Saint Martin of Caen. We show improvements obtained by modifying some aspects of the organization. Thereafter we tried to identify the specificities of sterilization services in several hospitals in order to perform a comparison of the different organization types and to identify the most efficient services. This comparison, realized with data obtained from a survey of establishments in region Rhône Alpes, relies on a ratio comparison, on the DEA method (Data Envelopment Analysis) and on a generic simulation model. In this thesis, we also offer tracks to analyze a generic sterilization service by using analytical stochastic methods. First, we present a survey on the use of stochastic models for the analysis of health care systems, then we study the possibility of using an analytical method to analyze our generic model of a sterilization service. Finally a queuing network model of a generic sterilization service is presented.GRENOBLE1-BU Sciences (384212103) / SudocGRENOBLE-GIPSA-lab (384212301) / SudocSudocFranceF

A generic model for the performance evaluation of centralized sterilization services

International audienceIn health establishments, the sterilization of surgical and exploration instruments plays a key role in the fight against infections. We present here the generic model structure of a centralized sterilization service. It is obtained using information provided by a survey we sent to health establishments in the Rhône-Alpes region, in France. This structure is then used to propose a queuing network model for a generic sterilization service, and to build a simulation model. This last model provides some performance parameters, which could not be obtained with the survey, and are useful for the comparison of health establishments performance