Showing papers presented at "AUTOTESTCON in 2005"

Integrated diagnosis and prognosis architecture for fleet vehicles using dynamic case-based reasoning

Abstract: This paper presents a hybrid reasoning architecture for integrated fault diagnosis and health maintenance of fleet vehicles. The aim of this architecture is to research, develop and test advanced diagnostic and decision support tools for maintenance of complex machinery. Artificial intelligence based diagnostic approach has been proposed with particular reference to dynamic case-based reasoning (DCBR). This system refines an asynchronous stream of symptom and repair actions into a compound case structure and efficiently organizes the relevant information into the case memory. Diagnosis is carried out into two steps for fast and efficient solution generation. First the situation is analyzed based on observed symptoms (textual descriptions) to propose initial diagnosis and generate corresponding explanation hypothesis. Next, based on the generated hypothesis relevant sensor data is collected and corresponding data analysis modules are activated for data-driven diagnosis. This approach reduces the computational demands to enable fast experience transfer and more reliable and informed testing. This system also tracks the success rates of all possible hypotheses for a given diagnosis and ranks them based on statistical evaluation criteria to improve the efficiency of future situations. Since the system can interact with multiple vehicles it learns about several operating environments resulting in a rich accumulation of experiences in relatively very short time. A distributed and generic architecture of this system is outlined from technical implementation point of view which can be used for widespread applications where both qualitative and quantitative observations can be gathered. Further, a concept of expanding this architecture for carrying out prognostic tasks is introduced.

Electronic prognostics - a case study using Global Positioning System (GPS)

Abstract: Prognostic health management (PHM) of electronic systems presents challenges traditionally viewed as either insurmountable or otherwise not worth the cost of pursuit. Recent changes in weapons platform acquisition and support requirements has spurred renewed interest in electronics PHM, revealing possible applications, accessible data sources, and previously unexplored predictive techniques. The approach, development, and validation of electronic prognostics for a radiofrequency (RF) system are discussed in this paper. Conventional PHM concepts are refined to develop a three-tier failure mode and effects analysis (FMEA). The proposed method identifies prognostic features by performing device, circuit, and system-level modeling. Accelerated failure testing validates the identified diagnostic features. The results of the accelerated failure tests accurately predict the remaining useful life of a COTS GPS receiver to within plusmn5 thermal cycles. The solution has applicability to a broad class of mixed digital/analog circuitry, including radar and software defined radio

Bayesian diagnosis and prognosis using instrument uncertainty

Abstract: How can diagnosis and prognosis systems be improved in the presence of uncertainty in test results? How can these uncertainties be identified and modeled? Can diagnosis be improved as a result of understanding these uncertainties? These questions represent the core problems to be explored in this paper. Specifically, we explore the process by which instrument uncertainty can be used to determine conditional probabilities of potential diagnoses given test results generated by these instruments. We then use that information to construct "Bayesian belief networks" with specific goal of maximizing diagnostic accuracy while minimizing construction complexity, and computational complexity. We then extend the ideas presented for Bayesian diagnosis to the prognostic, or predictive diagnostic problem

Return-on-investment (ROI) for electronic prognostics in mil/aero systems

Abstract: This paper describes a methodology for quantifying the return-on-investment (ROI) for the adoption of electronic prognostics in mil/aero systems. An example using the methodology will be taken from publicly-available data on switch-mode power supplies for the Eurofighter but the principles described are extensible to other mil/aero systems

A model-based approach to sequential fault diagnosis

Abstract: Fault diagnosis is crucial for the reduction of test & integration time and down-time of complex systems. In this paper, we present a model-based approach to derive tests and test sequences for sequential fault diagnosis. This approach offers advantages over methods that are based on test coverage of explicit fault states, represented in matrix form. Functional models are more easily adapted to design changes and constitute a complete information source for test selection on a given abstraction level. We introduce our approach and implementation with a theoretic example. We demonstrate the practical use in three case studies and obtain cost reductions of up to 59% compared to the matrix-based approach

Designing for health: a methodology for integrated diagnostics/prognostics

Abstract: A critical element of system readiness is the effectiveness of integrated diagnostics and prognostics. Errors in detection and isolation of failures cause unnecessary maintenance actions requiring additional troubleshooting time and replacement of could not duplicates (CNDs). Integrated diagnostics/prognostics is achieved through a systems engineering closed loop process from start to finish. Every step from conceptual phase through program shut down thrives on an integrated approach to insure maximum coverage of faults and unambiguous isolation while minimizing false alarms and re-test okays (RTOKs). An integrated health management system (HMS) methodology, proposed in this paper, connects functionality, failure modes and diagnostics/prognostics under one umbrella providing a conduit for tight traceability from requirements through design, analysis, integration, verification and validation, factory testing, and fielding while encouraging maturation through data collection. This framework minimizes errors between diagnostic/prognostic analyses and actual performance, maximizes test vertically, and paves the way for a lower risk fielded product. Iterative analyses and trade studies during the concept and development phases optimize diagnostic/prognostics approaches and architecture. Analyses and simulations during the development phase optimize health sensor selection, sensor placement, test effectiveness, and test strategies (i.e. embedded vs. external, test flow, test type etc.). Analyses and test data provide the foundation for the fidelity and accuracy of a diagnostic/prognostic reasoner, which selects test sequence, filters information and reports faults and their location. A data collection system facilitates diagnostic/prognostic effectiveness trending and identifies target areas for improvement as a function of maturation during the deployment, operations and support phases. This paper describes how all these segments weave together to create a seamless closed loop diagnostic/prognostic process that fits into the new DoD 5000.2 instruction: integrated defense acquisition, technology and logistics life cycle management framework

Graphical models for diagnosis knowledge representation and inference

Abstract: One popular approach for fault diagnosis is based on reasoning about the behavior of a system in failure space. Diagnosis is performed by considering a set of observations (or symptoms) and by explaining it in terms of a set of root causes. There are many modeling methods to capture the system's faulty behavior, such as behavioral Petri nets, multi-signal flow graphs, and Bayesian networks. In this paper, we will investigate the equivalence of these three modeling formalism by way of application to a car engine diagnosis problem, and discuss the advantages and disadvantages of each method

Attacking "bad actor" and "no fault found" electronic boxes

Abstract: A the percentage of what are termed "bad actor" and no fault found (NFF) electronic box in military weapon systems is steadily growing. These are boxes that fail during operation, but test NFF during back shop testing, or, that fail during back shop testing and then test NFF at the depot repair facility. During operation, an electronic box is stressed by various environmental conditions which are normally absent on a test bench. If there are cold or cracked solder joints, corroded or dirty connector contacts, loose crimp joints, hairline cracks in a ribbon cable trace, or other intermittent conditions, the intermittency can occur while the box is under stress conditions, yet seldom occur while the box is on a test bench at room temperature. Very little concerted effort is currently focused on detecting, isolating and repairing these intermittent problems. Virtually all testing activity simply tests the unit for normal operation, one function, one circuit, or one set of circuits at a time. If an intermittent circuit is not displaying its intermittent nature at the instant it is being tested, the intermittency remains undetected. A three-pronged effort is currently underway to attack and repair bad actor and NFF electronic boxes. The first is to collect detailed repair data to identify which boxes are bad actor and NFF units. The second is to collect test data to determine which units yield inconsistent test results between back shop testing and depot testing, and why. The third is to employ a system that detects and isolates electronic box intermittent circuits. This paper describes the success realized to date by employing each of the three techniques described above, and how they are now effectively being employed together to reduce maintenance costs and improve avionics reliability for the F-16 weapon system.

Implementing IEEE 1641 - a demonstration of portability

Abstract: For some years now, the Standards Technical Working Group for Automatic Test (STWGAT) has been developing the signal & test definition (STD) standard under the designation of IEEE 1641. In the year that 1641 has been formally released, a UK Ministry of Defence (MoD) sponsored study into the uses of the standard has been undertaken; producing a 1641 compliant test program set (TPS) and proving its portability across multiple, unique automatic test equipment (ATE) platforms. IEEE 1641 may be expressed in many commercial off-the-shelf (COTS) languages, including visual basic (VB), extendable mark-up language (XML) or C++. Two test program sets (TPS) have been produced, one in VB and one in XML (based on automatic test mark-up language (ATML) -test description). Through reference to the 1641 standard, these two test programs are identical and unambiguous in functionality. Just as tests can be described using 1641, so, too, can test resources. 1641 based resource descriptions have been produced for each of the ATE platforms used in this study. Resource management and allocation can be achieved automatically based upon a match of test signal requirements and resource signal descriptions.

Integrating PXI with VXI, GPIB, USB, and LXI instrumentation

Abstract: For large test systems, it is rare to find 100% coverage of all instrumentation needs in a single platform, making integration of multiple platforms an absolute necessity. This paper and presentation covers the common hardware and software techniques used to integrate PXI systems with VXI, GPIB, USB, and Ethernet/LXI instrumentation platforms. Considerations will include implications of bus interface selection, software driver models such as VISA and IVI, and hardware synchronization options between platforms

Anatomy of the next generation of ATE

Abstract: This paper provides an overview of several initiatives leading to the next generation of ATE and notes that the single biggest problem in ATE today is not the incorporation of advancing technology to achieve ever higher test capabilities in newly fielded ATE, rather it is the management of legacy and new ATE over a twenty year or more life cycle This paper discusses the benefit of creation of logistically compatible testers Logistics compatibility is obtained by identifying common test capabilities of current unique testers and consolidating those test requirements into common test resources Adding to the common test resources is the savings/benefits through the implementation of an evolving Institute of Electrical and Electronics Engineers (IEEE) standard which allows multiple sized interface test adapters (ITAs) to work with different ATE The IEEE-PI 505 receiver-fixture interface2 directly supports a compatible family of testers concept The paper notes there are several enabling technologies evolving in the industry that facilitate the common instrument approach such as virtual or synthetic instruments (SI), programmable bus emulators or bus simulators These have the flexibility to consolidate large numbers of obsolete, unique communications cards into a single test equipment asset This paper also discusses the advances in software technology that will become prevalent in future ATE Maintenance of test programs can be complicated and costly when using multiple operating systems and multiple test languages Consolidation of the test language and operating system into an easy-to-use, COTS-based software development environment reduces recurring maintenance and training costs Network-centric ATE approaches are also considered in this paper with the benefits provided The use of network and Web-based management of tester software and TPSs is noted as a great benefit in the reduction of software maintenance costs Use of a network connection and even the Internet allows software and on-line manuals to be managed in one location and provides for automatic updates, guaranteeing the use of the latest official versions of manuals and software The paper also discusses that Network and Web-based testers allow for information flow in the other direction, thus facilitating a centralized database to collect UUT failure data for tracking repair piece parts and for determining high failure rate issues and/or UUT repair history The final factor noted in this paper is the use of standards that provide for interfaces that are common and inter-operable across the industry All the concepts presented form the anatomy of viable future ATE systems If these concepts are not implemented in ATE designs, we as tax payers will continue to foot the bill for costly band-aid solutions in support of the war fighter

Introduction to the next generation automatic test system (NGATS)

Abstract: The next generation automatic test system (NGATS) is the latest addition to the integrated family of test equipment (IFTE), developed and managed by product manager, test, measurement and diagnostic equipment (PM TMDE). The NGATS, commonly known as the base shop test facility (V)6, joins the other BSTFs developed by the off platform, automatic test system program. NGATS is a highly mobile, rapidly deployable, general-purpose, reconfigurable automatic test system. The system is designed to support the testing and screening of all army weapon systems to maintain their readiness to shoot, move and communicate. Benefits of the NGATS include helping facilitate the standardization of army automatic test equipment, increasing weapon system availability and facilitating MOS consolidation. Additionally, it reduces repair parts inventory, increases mobility, deployability, affordability and supportability, reduces footprint of automated test equipment and screens for no evidence of failure (NEOF). NGATS assures compliance with joint NxTest architecture. NGATS will support the agile rapid global combat support (ARGCS) advanced concept technology demonstration (ACTD) by using a common framework for DoD automatic test systems (ATS). Spiral development of this system will ultimately modernize and replace three existing systems, direct support electronic systems test set (DSESTS), BSTF (V)3, and BSTF (V)5. The NGATS will not only support legacy systems but will also support new systems.

Pros and cons of using COTS products

Abstract: In recent years, there has been a general trend in the automated test industry to migrate to commercial off the shelf (COTS) software and hardware. This has created a lot of controversy. The drive to incorporate COTS software and hardware is often based on incomplete or inaccurate information. Using COTS products does offer many advantages; however there are also disadvantages, many of which are not readily apparent. For instance, many experienced engineers are reluctant to move to COTS, if for no other reason than a general resistance to change. Many "seasoned" engineers have the "not invented here" mentality that generates a general distrust for COTS products in general. Although it is generally a good idea not to accept something without verifying its capabilities, it is also not a good idea to reject something on general principle. The author believes that if COTS products are incorporated giving proper regard to the issues discussed in this paper, the pros are emphasized and the cons minimized. For example, recently our team convinced one of its customers, (via demonstrations) to make a significant modification to their TPS approach (from an in house solution to a COTS-based solution). The team demonstrated that by exploiting a COTS product's built-in capabilities, the customer's functional interface layer and database (a large amount of C++ code, a year in the making) was not required. Not only did this reduce the amount of code required to be under CM control, but more importantly, greatly simplified the development and debug environment for the test developer. This paper discusses the advantages and disadvantages (pros and cons) of using COTS software and hardware for some of the major areas of interest related to automated test solutions

XVIML: an extensible virtual instrument markup language

Abstract: In this paper, an assembling mechanism of virtual instrument and an extensible virtual instrument markup language are proposed. Using the Unix pipe mechanism, the virtual instrument application is separated into a group of pipeline components, which are connected together by pipelines. When the measurement data flow through connected pipeline components, the data are processed step by step until the end of pipelines. In the base of pipeline components, the assembling mechanism of virtual instrument is proposed. And a script language is proposed to define the assembling of virtual instrument. The language is created in the base of XML and is composed of XML tags that are used to describe the building interfaces of pipeline components. The language has an open XML structure. New pipeline components and their XML tags can be easily added to the language. To let the virtual instrument platform identify new XML tags automatically, a dynamic script interpreter is also proposed

Self-evolution in knowledge bases

Abstract: From the volumes of data that can be obtained today, information extraction has been a very challenging task. An organized set of information such that it can be considered as knowledge is yet another level of abstraction that puts these pieces of information in place, in space and time, so that when combined, they make sense, thus forming what is commonly known as a Knowledgebase (KB). A 'self-evolution' process in a KB is meant to handle such information related issues as incorrect information, missing information, and incomplete information. Other maintenance issues are related to data organization that results in incorrect or inefficient information retrieval, and removal of unnecessary data. The concepts presented in this paper are inspired by the overall vision for an asset readiness decision-making system

Supporting hardware independence in the next generation of automatic test equipment

Abstract: Hardware independence enables the replacement of obsolete instruments and the execution of TPSs on different hardware platforms. The emergence of new software technologies creates opportunities for developing more maintainable and interoperable ATS software. In this context, it is important to recognize the valuable characteristics of existing software solutions that support hardware independence and to preserve these characteristics while migrating to newer technologies. The paper contains a comparative analysis of existing software solutions that support hardware independence, including SCPI, IVI, ATLAS and IEEE 1641. The principle of signal-based, UUT-oriented specification of test behavior, combined with the use of general-purpose programming languages appears today as the most effective path for achieving a high degree of instrument independence in software solutions based on modern software technologies. The paper recommends a set of architectural and functional characteristics for the design of such solutions

Can you make one size fit all? [synthetic instrument]

Abstract: With the contract award of the ARGCS (agile rapid global combat support) ACTD (advanced concept technology demonstration) last September, the DoD is making great advances toward a more cost efficient and coordinated military support organization. One attribute of ARGCS is to develop and demonstrate a synthetic instrument as a possible replacement of the growing plethora of general-purpose and customized test equipment currently deployed in the military's most widely used automatic test systems (ATS). This paper describes an ideal synthetic instrument (SI), technology trends that make the ideal SI possible, trade-offs instrument manufacturers are making based on available technology, ramifications to test systems integrators and users based on these trade-offs.

Exploring LXI's advanced capabilities

Abstract: The proposed LXI (LAN extensions for instrumentation) specification defines a rich collection of capabilities that allow LAN-connected instruments to perform sophisticated test and measurement functions. This paper describes a prototype test system that demonstrates the power and flexibility of combining LXI with embedded test script processing. It demonstrates the use of LXI LAN triggering and other LXI features; it also includes performance data and optimization tips

Tradeoffs in synthetic instrument design and application

Abstract: There are efforts underway within industry to develop synthetic instrumentation (SI) as a complement to traditional monolithic instrumentation designs. This provides flexibility in the selection of SI components to match the performance level required and to also overcome obsolescence issues. The synthetic instrument concept is attractive because signal processing and generation can be handled by platform independent software routines. The capability of an instrument can be changed or extended by simply down loading a new program or upgrading a driver. Common programming standards such as IVI can simplify transitioning to replacement hardware and software when obsolescence becomes an issue. With the explosion in personal computer development, processing power has become an inexpensive commodity. A/D and D/A converters are becoming commodities as well, with increasing speed and resolution every year. Signal conditioning remains a custom element as it usually must be tailored for specific applications. Leveraging COTS hardware and software can reduce cost and shorten system development times. As with any new concept, application of synthetic instrument raises issues that must be considered. Synthetic instruments impact overall test system architecture. The impact depends on the complexity of synthetic instrument function and where the signal processing functionality (software) is located. Emulation of legacy instrumentation is another issue. Since the SI measurement processes used are typically different from the legacy instrument, the synthetic instrument may not perfectly emulate the legacy device. For military test systems where longevity and user maintainability are prime requirements, the logistics tail must be considered. Development cycles for military test equipment are long by commercial standards. The world of COTS changes rapidly and it is not uncommon for COTS technology to be obsolete before the system is fielded. Another concern is environmental standards. Military systems typically have stringent requirements for shock, vibration, temperature, humidity, EMI/EMC, and other environmental requirements that commercial systems are not required to meet. This paper examines some of these issues related to synthetic instrumentation. As always with engineering, there is no perfect answer, there are only tradeoffs to be optimized

Automated test equipment synthetic instrumentation

Abstract: When the USAF's F-15 became operational in the mid-1970s, intermediate avionics test support was provided by specific test stations designed to support technology workload groups, ranging from controls and displays to communications/navigation equipment, with many of the test packages requiring complex interface test adapters (ITAs). These testers are quickly becoming obsolete and more difficult and costly to maintain because replacement parts are no longer available. Alternative technical solutions are required to ensure fielded avionics test equipment technology maintains pace with fielded systems and operational requirements, ensuring the availability of mission critical avionics assets. In order to demonstrate a solution to these growing issues, Boeing is tailoring an emerging F-15 support system by inserting agile rapid global combat support (ARGCS) technologies including synthetic instrumentation (SI), to reduce the use of traditional COTS (commercial-off-the-shelf) instruments. This type of arrangement highlights the potential benefits of SI, which include the use of non-active (wire only) ITAs to the USAF. During the past decade the USAF has expressed a desire for this passive ITA hardware design, since it facilitates reduced development time, increases equipment reliability/availability and decreases long-term sustainment cost compared to the existing specialized complex active hardware design approach. During this 12-month program, SI is being integrated into the selected ATE platform to provide analog, serial bus test and video capability by replacing existing VXI-based instruments. Several F-15 line replaceable unit (LRU) test program sets (TPS) are being integrated and/or adapted to use the Sl-equipped support system, demonstrating the ability to rapidly prototype TPSs. By utilizing parallel testing capabilities of the latest technology synthetic instruments, a significant reduction in test times is also expected. This paper discusses the engineering effort required to integrate SI into the selected ATE platform including the hardware and software design approaches employed, as well as the methodology used to re-engineer TPS designs to leverage SI and the benefits realized during the project as well as potential applications to DoD customers

Using XML transactions to perform closed-loop diagnostics in network centric support environments

Abstract: Extensible markup language (XML) transactions offer a methodology for defining standard communication interfaces as a means of promoting interoperability between network centric support (NCS) environments with the purpose of performing closed-loop diagnostics. Interoperability is established through the use of standardized XML schemas that define common XML constructs and then give these constructs context sensitive meaning via the use of an XML transaction. The core ideology behind an XML transaction is the creation of a standardized dialect to be used by two or more parties during instances of information exchange within which the XML transaction type contains the information related to the context of the exchange. The XML transaction methodology not only provides for the creation of a common dialect to be used by two or more parties during instances of information exchanges, it also reduces the complexity of maintaining individual schemas for each type of data exchange; it readily supports required field data validation via the direct application of the XML schema against an XML instance document instead of performing this function programmatically; it reduces the complexity on system integrators by allowing them to only gain familiarity of the required transactions; it readily supports both synchronous and asynchronous communication; and it provides a placeholder for standardized header information which is needed within every transaction. XML transactions are currently being investigated by the automatic test markup language (ATML) working group as a standardized way to establish connectivity between maintenance systems in NCS environments. While the ATML XML transaction specifications are still in draft format, they have been utilized on the Smart TPS project to perform closed-loop diagnostics in a network centric environment. Initial results from the Smart TPS project have proven that the use of XML transactions is a viable method for performing closed-loop diagnostics in network centric environments. Given the aforementioned benefits of XML transactions, one can see that they readily yield themselves as an emerging technology for enabling closed-loop diagnostics in a NCS environment. The XML transaction concept gives every node within the closed- loop diagnostic environment a language specification that defines the grammar with which that node can communicate with any other node. Furthermore, the XML transaction methodology takes the concept a step further through the definition of the types of transactions that exist for nodes interested in performing closed-loop diagnostics

Self-evolving, advanced test stand reasoning for closed loop diagnostics

Abstract: Advanced test stand reasoning can yield dramatically increased Line Replaceable Unit (LRU) operational availability through reduction of Mean Time to Repair (MTTR) while offering better utilization of related maintenance and test equipment resources However, technical challenges related to development of reasoning systems, typically requiring expert LRU domain knowledge, present hurdles that can be prohibitive Reasoning methods developed using simple pattern recognition and repair instance statistics offer a first order approach that is functional from a proof of concept perspective Unfortunately, the small numbers of statistics available historically provide reduced reasoner reliability and effectiveness when confronted with dynamic and complex avionic systems This paper discusses the issues, trade-offs, and potential benefits to be gained through the application of robust, self-evolving, hybrid reasoning techniques A reasoner that can utilize and leverage the constraints found in typical test stand procedures to provide a best, safe path to diagnosis, while learning and optimizing in-situ, may offer an ideal, scaleable solution for optimizing test stand operations Related information management and diagnostic model visualization techniques are also presented in the context of diagnostic and avionic system evaluation and improvement

LAN-based measurement triggering using LXI instrumentation

Abstract: The LAN Extensions for Instrumentation (LXI) standard introduces new concepts in signal triggering that have the potential to enable new measurement systems and simplify older ones. This paper presents an overview of the LXI triggering model. LXI triggering includes both hardware and LAN-based signals that can be used together to optimize a measurement application. Like VXI and MMS systems before it, LXI systems utilize a standard backplane; but unlike the older systems, LXI uses the ubiquitous Ethernet LAN standard. Triggers can be broadcast over the LAN to multiple devices simultaneously. In addition, the LXI standard includes an optional LXI trigger bus. From the API level, the triggering model for both LAN and the trigger bus are identical. This paper briefly compares the performance specs of LXI triggering with VXI (VME bus) and MMS (MSIB bus) systems. It explains the different types of triggering that can be obtained using the LAN and the LXI trigger bus. A brief description of the triggering API is given, along with a description of the LXI triggering system architecture. Since the characteristics of LAN triggers differ from traditional hardware triggers, tradeoffs between the two types of triggers are discussed

A systems approach to diagnostic ambiguity reduction in naval avionic systems

Abstract: There are inefficiencies in the current United States (U.S.) Navy maintenance system. These inefficiencies waste resources and manpower. Platform-level diagnostics is relegated primarily to built-in-test (BIT). However, BIT is not entirely reliable. Enhanced Organizational level (0-level) diagnostic functionality is needed to reduce ambiguities between multiple weapons Replaceable Assemblies (wRA's) and interconnects; thus markedly reducing rates of "cannot duplicate/no fault found" (A-799) conditions. This paper describes an effort at the Naval Air Systems Command (NAVAIR) Lakehurst to improve avionic diagnostics at both the 0- level and the Intermediate level (I-level) through the bi-directional exchange of information between these maintenance levels and the use of virtual instrumentation at the 0- level. The Integrated Diagnostics and Automated Test Systems (IDATS) team at NAVAIR Lakehurst has established an environment which closely models the 0-level and I-level in terms of dataflow. This environment was used to demonstrate several concepts which can be used to augment BIT, enabling smarter maintenance decisions at both levels of maintenance. These concepts were demonstrated using a data processor from an F-14 Avionics weapons Group 9 (AWG-9) radar system.

Use of ontologies for decision support generation and analysis

Abstract: The purpose of this paper is to illustrate the benefits of using ontologies to generate various artificial intelligence exchange and service tie to all test environments (AI-ESTATE - IEEE Std 1232trade-2002) diagnostic models. One of these benefits is the ability to take engineering information and create multiple models from the same information, thereby reducing the possibility of translation errors. Another benefit offered in the use of an ontology is the ability to determine all possible diagnoses that lead to a particular indictment, thereby making the diagnostic model's coverage explicit. The ontology will be created using the OWL Web ontology language. The generation of the AI-ESTATE diagnostic models will be based on the use of description logic. Description logic will also be used to perform the coverage analysis

Implementing advanced timing and synchronization architectures in PXI systems

Abstract: Mixed-signal and high-channel-count test systems typically require tight synchronization between instrument components. The PXI backplane contains system reference clock, PXI trigger bus, and star trigger bus resources designed for precise and flexible timing and synchronization. Engineers can take advantage of these resources to synchronize instruments across the PXI backplane using numerous synchronization schemes. Additionally, the PXI platform can be used to implement advanced timing and synchronization architectures such as the synchronization of instruments to external timebases such as GPS

Bayesian modeling: an amendment to the AI-ESTATE standard

Abstract: Recent advances in diagnostic technology have resulted in the need to examine these technologies for expanding current work in diagnostic standards. Specifically, the use of Bayesian networks for system diagnosis is becoming more common, thus warranting consideration of a Bayesian modeling within IEEE Std 1232 (AI-ESTATE). In the following, we present a discussion of Bayesian diagnosis as a basis for introducing a new information model to support exchange Bayesian knowledge. We also describe a simple extension to the model to support system prognosis. Finally, we discuss recent initiatives within the IEEE to update their standard exchange mechanisms to support XML as "preferred" medium

PXI Express: extending backplanes to 6 Gbyte/s while maintaining backwards compatibility

Abstract: The PXI Express specification integrates PCI Express signaling into PXI to enable new levels of performance in modular instrumentation systems. By leveraging the commercially available PCI Express industry standard, future PXI systems can benefit from both very high performance as well as high component availability at lower costs. PXI Express maintains backwards compatibility with the PXI specifications in three ways. First, software compatibility is provided inherently in the architecture, as the PCI Express software model is backwards compatible with PCI by design. Second, PXI Express defines slots that accept either a high performance module that uses PCI express for data transfers, or a module designed to the PXI specification using PCI for data transfers. Third, the PXI Express specification allows for chassis with PXI slots that do not have PCI Express signaling. This combination of software and hardware compatibility allows both customers and vendors to preserve their investments in existing systems, modules, software, and designs

Development of a new interchangeable virtual instrument class specification

Abstract: In today's world, rapidly changing technology and high costs associated with developing and maintaining ATE software push the need for reusability and ease of upgrading or replacing components in test systems intended to be used over a long period of time. The interchangeable virtual instrument (IVI) foundation is tackling these issues by: "Promoting specifications for programming test instruments that simplify interchangeability, provide better performance, and reduce program development and maintenance cost". An interchangeable virtual instrument (IVI) class specification defines the base capabilities and extensions for an instrument type (such as a function generator or oscilloscope). This specification defines the application programming interface (API) used to develop an IVI class-compliant driver. Systems & Electronics Inc. and Boeing are jointly chairing an IVI foundation working group to define an IVI class specification for a counter/timer. Based on the experiences of characterizing the counter/timer specification, this paper explores the process of creating a new class specification for an instrument type that does not already have a specification defined. Topics such as steps to effective specification development, obstacles encountered, and how to keep the specification moving forward are discussed

Knowledge base to manage the grading and selection of testability guidelines

Abstract: A management system, called The TestEnablisttrade is introduced which can deal with the large variety of design for testability (DFT) guidelines available in industry. It is a commonly accepted notion that the most effective DFT technique is one that is incorporated during the normal design activity. Designers, however, may have difficulty recognizing where DFT is needed and which of the myriad of guidelines is applicable to a particular circuit or signal. The selected test strategy and mix of inspection, automatic test equipment (ATE) and built-in self test (BIST) utilized also impacts the selection of guidelines. The TestEnablist is tasked with monitoring the design's testability and to recommend only those guidelines, which are applicable to the circuit and are appropriate for the selected test strategy. Designers are then able to choose among applicable DFT guidelines while they are designing. The TestEnablist accomplishes these tasks by utilizing a knowledge base of industry-generated testability guidelines that are indexed to the selected test strategy as well as to specific design criteria and testability attributes. This paper describes the requirements, use and implementation of The TestEnablist