Arquitectura PXI multiprocesadora para adquisición y procesado de datos en tiempo real : aplicación a diagnósticos en entornos de fusión por confinamiento magnético

La fusión nuclear por confinamiento magnético se ha convertido en las últimas décadas en línea de investigación prioritaria en gran parte de los países desarrollados. La explotación científica de cualquier dispositivo de fusión va orientada a obtener el mayor conocimiento posible de las propiedades físicas del plasma. Para ello se utilizan una amplia variedad de sistemas de medida, denominados diagnósticos en la terminología del entorno. Debido a las altas temperaturas existentes en el interior del plasma, la gran mayoría de los resultados se obtienen por métodos indirectos, convirtiendo las magnitudes físicas en señales eléctricas. Los diferentes diagnósticos asociados a los dispositivos de fusión incorporan de forma genérica medios hardware y software para la digitalización de señales, lectura e integración de datos en bases de datos y aplicaciones para el análisis de los resultados obtenidos. Todos los dispositivos existentes en la actualidad son dispositivos "pulsados", es decir, se produce un "pulso", de una duración determinada, durante el cual se aplica al dispositivo energía suficiente como para lograr confinar el plasma en su interior. La aplicación de esta energía es también conocida en la terminología del entorno como descarga. Los pulsos de la mayoría de los dispositivos son de corta duración (del orden de segundos o fracciones de segundos), aunque existen algunos dispositivos en los que la descarga tiene una duración superior (del orden de centenas de segundos). En este sentido, los objetivos de la comunidad internacional se centran en aunar esfuerzos que permitan aumentar la duración de las descargas. Fruto de ese esfuerzo ha sido la génesis de ITER, una gran instalación de fusión proyectada por los principales países, cuyo objetivo principal será demostrar la viabilidad científica y tecnológica de la fusión nuclear como fuente de energía. Ese aumento del tiempo de descarga obligará a un cambio en el ciclo clásico de operación en fusión. Mientras en los dispositivos de pulso corto es posible realizar la adquisición y el almacenamiento de los datos durante la descarga, para su procesado off-line posterior, se necesitarán soluciones de adquisición y procesado de datos on-line para pulsos largos y, en último extremo, para estado estacionario. La realización de esta tesis doctoral se centra en la definición y el desarrollo de una arquitectura PXI multiprocesadora orientada a la adquisición y el procesado de datos en tiempo real en entornos de fusión por confinamiento magnético. Esta arquitectura debe permitir escalar la capacidad de procesado de los sistemas PXI en función del diagnóstico al que se dedique cada sistema. Esto permitirá aplicar esta solución en dispositivos de fusión con experimentos de larga duración y permitirá aproximarse a una solución válida para el estado estacionario. Además, se pretende aplicar la nueva arquitectura desarrollada al diagnóstico de bolometría del TJ-II (CIEMAT), de forma que la adquisición de los datos relativos al mismo y su procesado pueda hacerse en paralelo, cuestión no resuelta en la actualidad. Actualmente las tecnologías basadas en PXI que se comercializan no son capaces de soportar el volúmen de procesamiento necesario para estas aplicaciones, ya que la capacidad de procesado que presenta el sistema está restringida a la del propior controlador del mismo. La solución que se propone en esta tesis pasa por insertar en los chasis PXI estándar una o varias tarjetas procesadoras y por desarrollar los mecanismos necesarios para que, desde el controlador del sistema, se pueda distribuir el procesado de los diferentes canales adquiridos entre el propio controlador y las tarjetas procesadoras adicionales. Esta arquitectura es totalmente innovadora ya que permite el escalado en la capacidad de procesado global que puede presentar un sistema PXI. Por otro lado, se persigue facilitar la participación remota en entornos de fusión. Para ello, se pretende desarrollar un sistema de procesado dinámico de datos que permita a los usuarios, locales o remotos, gestionar on-line la ejecución de algoritmos de procesado de datos codificados en un lenguaje de alto nivel (LabVIEW) sobre el sistema desarrollado

Test-bed of a real time detection system for L/H and H/L transitions implemented with the ITMS platform

A basic requirement of the data acquisition systems used in long pulse fusion experiments is to detect events of interest in the acquired signals in real time. Developing such applications is usually a complex task, so it is necessary to develop a set of hardware and software tools that simplify their implementation. An example of these tools is the Intelligent Test and Measurement System (ITMS), which offers distributed data acquisition, distribution and real time processing capabilities with advanced, but easy to use, software tools that simplify application development and system setup. This paper presents the application of the ITMS platform to solve the problem of detecting L/H and H/L transitions in real time based on the use of efficient pattern recognition algorithms

Real time plasma disruptions detection in JET implemented with the ITMS platform using FPGA based IDAQ

The use of FPGAs in data acquisition cards for processing purposes allows an efficient real time pattern recognition algorithm implementation. Using 13 JETs database waveforms an algorithm for detecting incoming plasma disruptions has been implemented. This algorithm is written in MATLAB using floating point representation. In this work we show the methodology used to implement the real time version of the algorithm using Intelligent Data Acquisition Cards (IDAQ), DAQ devices with field programmable gate array (FPGA) for local processing. This methodology is based on the translation of the MATLAB code to LabVIEW and the final coding of specific pieces of code in LabVIEW for FPGA in fixed point format. The whole system for evaluating the real time disruption detection (RTDD) has been implemented using the Intelligent Test and Measurement System (ITMS) platform. ITMS offers distributed data acquisition, distribution and real time processing capabilities with advanced, but easy to use, software tools that simplify application development and system setup. The RTDD implementation uses a standard PXI/PXIe architecture. Two 8 channel analog output cards play JETs database signals, two 8 channel DAQ with FPGA acquire signals and computes a feature vector based in FFT analysis. Finally the vector acquired is used by the system CPU to execute a pattern recognition algorithm to estimate an incoming disruption

Exploiting graphic processing units parallelism to improve intelligent data acquisition system performance in JET's correlation reflectometer

The performance of intelligent data acquisition systems relies heavily on their processing capabilities and local bus bandwidth, especially in applications with high sample rates or high number of channels. This is the case of the self adaptive sampling rate data acquisition system installed as a pilot experiment in KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. In order to do so it must transfer acquired data to a memory buffer in the host processor and run heavy computational algorithms for each data block. The processing capabilities of the host CPU and the bandwidth of the PXI bus limit the maximum sample rate that can be achieved, therefore limiting the maximum bandwidth of the phenomena that can be studied. Graphic processing units (GPU) are becoming an alternative for speeding up compute intensive kernels of scientific, imaging and simulation applications. However, integrating this technology into data acquisition systems is not a straight forward step, not to mention exploiting their parallelism efficiently. This paper discusses the use of GPUs with new high speed data bus interfaces to improve the performance of the self adaptive sampling rate data acquisition system installed on JET. Integration issues are discussed and performance evaluations are presente

Implementation of local area network extension for instrumentation standard trigger capabilities in advanced data acquisition platforms

Synchronization mechanisms are an essential part of the real-time distributed data acquisition systems (DASs) used in fusion experiments. Traditionally, they have been based on the use of digital signals. The approach known as local area network extension for instrumentation (LXI) provides a set of very powerful synchronization and trigger mechanisms. The Intelligent Test Measurement System (ITMS) is a new platform designed to implement distributed data acquisition and fast data processing for fusion experiments. It is based on COMPATPCI technology and its extension to instrumentation (PXI). Hardware and software elements have been developed to include LXI trigger and synchronization mechanisms in this platform in order to obtain a class A LXI instrument. This paper describes the implementation of such a system, involving the following components: commercial hardware running a Linux operating system; a real-time extension to an operating system and network (RTAI and RTNET), which implements a software precision time protocol (PTP) using IEEE1588; an ad hoc PXI module to support hardware implementation of PTP-IEEE 1588; and the multipoint, low-voltage differential signaling hardware LXI trigger bus. ©2008 American Institute of Physic

Integrated electronic system for ultrasonic structural health monitoring

A fully integrated on-board electronic system that can perform in-situ structural health monitoring (SHM) of aircraft?s structures using specifically designed equipment for SHM based on guided wave ultrasonic method or Lamb waves? method is introduced. This equipment is called Phased Array Monitoring for Enhanced Life Assessment (PAMELA III) and is an essential part of overall PAMELA SHM? system. PAMELA III can generate any kind of excitation signals, acquire the response signals that propagate throughout the structure being tested, and perform the signal processing for damage detection directly on the structure without need to send the huge amount of raw signals but only the final SHM maps. It monitors the structure by means of an array of integrated Phased Array (PhA) transducers preferably bonded onto the host structure. The PAMELA III hardware for SHM mapping has been designed, built and subjected to laboratory tests, using aluminum and CFRP structures. The 12 channel system has been designed to be low weight (265 grams only), to have a small form factor, to be directly mounted above the integrated PhA transducers without need for cables and to be EMI protected so that the equipment can be taken on board an aircraft to perform required SHM analyses by use of embedded SHM algorithms. Moreover, the autonomous, automatic and on real-time working procedure makes it suitable for the avionic field, sending the corresponding alerts, maps and reports to external equipment

Configuration and supervision of advanced distribuited data adquisition and processing systems for long pulse experiments using JINI technology.

The development of tools for managing the capabilities and functionalities of distributed data acquisition systems is essential in long pulse fusion experiments. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is a technology that permits implementation of a scalable data acquisition and processing system based on PXI or CompactPCI hardware. Several applications based on JINI technology have been developed to enable use of this platform for extensive implementation of distributed data acquisition and processing systems. JINI provides a framework for developing service-oriented, distributed applications. The applications are based on the paradigm of a JINI federation that supports mechanisms for publication, discovering, subscription, and links to remote services. The model we implemented in the ITMS platform included services in the system CPU (SCPU) and peripheral CPUs (PCPUs). The resulting system demonstrated the following capabilities: (1) setup of the data acquisition and processing to apply to the signals, (2) information about the evolution of the data acquisition, (3) information about the applied data processing and (4) detection and distribution of the events detected by the ITMS software applications. With this approach, software applications running on the ITMS platform can be understood, from the perspective of their implementation details, as a set of dynamic, accessible, and transparent services. The search for services is performed using the publication and subscription mechanisms of the JINI specification. The configuration and supervision applications were developed using remotely accessible (LAN or WAN) objects. The consequence of this approach is a hardware and software architecture that provides a transparent model of remote configuration and supervision, and thereby a means to simplify the implementation of a distributed data acquisition system with scalable and dynamic local processing capability developed in a fusion environment

Self-adaptive sampling rate data acquisition in JET’s correlation reflectometer

Data acquisition systems with self-adaptive sampling rate capabilities have been proposed as a solution to reduce the shear amount of data collected in every discharge of present fusion devices. This paper discusses the design of such a system for its use in the KG8B correlation reflectometer at JET. The system, which is based on the ITMS platform, continuously adapts the sample rate during the acquisition depending on the signal bandwidth. Data are acquired continuously at the expected maximum sample rate and transferred to a memory buffer in the host processor. Thereafter the rest of the process is based on software. Data are read from the memory buffer in blocks and for each block an intelligent decimation algorithm is applied. The decimation algorithm determines the signal bandwidth for each block in order to choose the optimum sample rate for that block, and from there the decimation factor to be used. Memory buffers are used to adapt the throughput of the three main software modules _data acquisition, processing, and storage_ following a typical producer-consumer architecture. The system optimizes the amount of data collected while maintaining the same information. Design issues are discussed and results of performance evaluation are presented

Design of an advanced intelligent instrument with waveform recognition based on the ITMS platform

Searching for similar behavior in previous data plays a key role in fusion research, but can be quite challenging to implement from a practical point of view. This paper describes the design of an intelligent measurement instrument that uses similar waveform recognition systems (SWRS) to extract knowledge from the signals it acquires. The system is perceived as an Ethernet measurement instrument that permits to acquire several waveforms simultaneously and to identity similar behaviors by searching in previous data using distributed SWRS. The implementation is another example of the advantages that local processing capabilities can provide in data acquisition applications

Integrated phased array transducer for on-board structural health monitoring

Permanently bonded onto a structure, an integrated Phased Array (PhA II) transducer that can provide reliable electromechanical connection with corresponding sophisticated miniaturized ?all in one? SHM electronic device installed directly above it, without need for any interface cabling, during all aerospace structure lifecycle phases and for a huge variety of real harsh service environments of structures to be monitored is presented. This integrated PhA II transducer [1], as a key component of the PAMELA SHM? (Phased Array Monitoring for Enhanced Life Assessment) system, has two principal tasks at the same time, reliably transceive elastic waves in real aerospace service environments and serves as a reliable sole carrier or support for associated integrated on-board SHM electronic device attached above. The PhA II transducer successfully accomplished both required task throughout extensive test campaigns which included low to high temperature tests, temperature cycling, mechanical loading, combined thermo- mechanical loading and vibration resistance, etc. both with and without SHM device attached above due to RTCA DO-160F