第一篇文献展示教学课件.ppt

4- PHM Challenge of PHM methods Fleet-level PHM for the modern complex systems Distributed PHM for considering different degrees of uncertainty A distributed intelligent dynamic maintenance management system Agents at different system levels must be defined Different types of degradation or fault should be included Optimization for different objectives and constraints Two strategic problems Evaluation for adopting advanced maintenance policies ROI (the return on investment) Choice of Best PHM method： 4- PHM Illustrations: The practicing fields include Boeing 737 display、medical devices 、commercial aircraft、wind power system、LED lighting systems、airline industry. LCC of Unscheduled maintenance LCC of Adopting PHM Investment cost of PHM Investment cost of PHM 4- PHM Gaps for existing approaches to evaluate the ROI of a PHM methods Specific applications Without considering the impact of PHM performance on the economic benefit Without taking into account the uncertainties of the model parameters A more general framework to calculate the ROI of a PHM approach The investment costs The avoided cost A set of PPIs : is needed for the comparative analysis of the different models leading to the choice of the one to be implemented. 4- PHM The prognostic models are classified into : Directly from the raw data Indirectly on the basis of a Health Index (Being monotonic and with defined trend) RUL-based models Degradation-based models 4- PHM The PPIs can be primarily classified into: Accuracy -- Precision -- Stability -- Spill-over -- The closeness between the model output and the true data The spread of the model output The sensitivity of the model The effects of varying the inputs on the models performance CO: The aggregation technique is needed to intuitively grasp the meaning of the results provided by the PPIs and must deliver a clear suggestion for the prognostic model to be chosen among the available ones. 4- PHM The precision index PI where is a measure