AUTOTESTCON 

Abstract: In this paper, we present a comprehensive methodology for a formal, but intuitive, cause-effect dependency modeling using multi-signal directed graphs that correspond closely to hierarchical system schematics and develop diagnostic strategies to isolate faults in the shortest possible time without making the unrealistic single fault assumption A key feature of our methodology is that our models lend naturally to real-world necessities, such as system integration and hierarchical troubleshooting >

Abstract: Prognostics and health management (PHM) is an approach to system life-cycle support that seeks to reduce/eliminate inspections and time-based maintenance through accurate monitoring, incipient fault detection, and prediction of impending faults. Coupled with autonomic logistics for unprecedented responsiveness, cost effectiveness, and mission availability, PHM is largely automated in its application. Incorporating the principles of condition-based maintenance (CBM) along with the tenets of reliability-centered maintenance (RCM), the PHM paradigm extends these capabilities and provides a robust environment to optimize maintenance and logistics for increased operational availability (A0), and reduced life-cycle costs (LCC) while potentially increasing the reliability and life expectancy of mechanical, structural, and electronic systems. Driven by a demand for greater reliability at reduced cost and fueled by technological advancements, the PHM contribution to an already robust and confounding vocabulary surrounding maintenance and logistics is significant. As adopters of PHM technology attempt to define requirements and performance parameters, difficulties encountered with various non- standardized terminology indicate that the PHM vocabulary merits a lexical review. This paper will provide a compendium of PHM terminology along with definitions and examples, derived from the authors' experience in the implementation of PHM systems. Coalescing existing vocabularies and introducing, formally, the new lexicon of maintenance and logistics, the authors seek to aid in clarification of the emerging dialogue of life-cycle support.

Abstract: Conventional maintenance strategies, such as corrective preventive maintenance, are not adequate to fulfill the needs of expensive and high availability industrial systems. A new strategy based on forecasting of system degradation through a prognostic process is required. The recent advances in model-based design technology have realized significant time savings in product development cycle. These advances facilitate the integration of model-based diagnosis and prognosis of systems, leading to condition-based maintenance and increased availability of systems. With an accurate simulation model of a system, diagnostics and prognostics can be synthesized concurrently with system design. In this paper, we develop an integrated prognostic process based on data collected from model-based simulations under nominal and degraded conditions. Prognostic models are constructed based on different random load conditions (modes). An interacting multiple model (IMM) is used to track the hidden damage. Remaining life prediction is performed by mixing mode-based life predictions via time-averaged mode probabilities. The solution has the potential to be applicable to a variety of systems, ranging from automobiles to aerospace systems.

Abstract: To advance the field of electronics prognostics, the study of transistor fault modes and their precursors is essential. This paper reports on a platform for the aging, characterization, and scenario simulation of gate controlled power transistors. The platform supports thermal cycling, dielectric over-voltage, acute/chronic thermal stress, current overstress and application specific scenario simulation. In addition, the platform supports in-situ transistor state monitoring, including measurements of the steady-state voltages and currents, measurements of electrical transient response, measurement of thermal transients, and extrapolated semiconductor impedances, all conducted at varying gate and drain voltage levels. The aging and characterization platform consists of an acquisition and aging hardware system, an agile software architecture for experiment control and a collection of industry developed test equipment.