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Measurement uncertainty estimation using statistical methods


Technical University of Denmark


General course objectives:
Statement of uncertainty is mandatory by current quality standards, starting from ISO 9001 and, more specifically, ISO 17025, that governs management of testing and measurement laboratories. A fundamental reference text on this topic has been published by ISO: “Guide to the expression of Uncertainty in Measurement”, currently referred to as “The GUM” and embodied into the ENV 13005 European standard. Statistical procedures dictated by GUM cover a broad range of applications. Besides definition of such a delicate undertaking as evaluation of measurement uncertainty with a clear set of rules accepted worldwide, they cater for planning measurement and testing work aimed at specific levels of uncertainty, in order to avoid failure to reach required accuracy, and costly overdesign. These methods - covering both specific metrological work, such as e.g. calibration of sensors and instrument systems, and generic testing work –also deal with applications in the activities of design and planning of production processes. The objectives of this course are to describe the main methods to be adopted and to present some applications in the field of measurement, design and production engineering.

Learning objectives:
A student who has met the objectives of the course will be able to:
  • Describe the relevance of uncertainty in measurement
  • Recognise the main factors affecting the uncertainty of a measurement
  • Describe the international approach to expressing the uncertainty of measurement
  • Apply the uncertainty evaluation technique proposed by GUM
  • Analyse the uncertainty budget connected with a measurement procedure
  • Produce an uncertainty budget for a given engineering application
  • Manage the problems connected with mechanical design in statistical way
  • Manage the problems connected with production engineering in statistical way

Contents:
1 Basic concepts Introduction. Why it is necessary to evaluate uncertainty: requirements of Quality Standards and transfer of measurement information 1.1 Measurement uncertainty Typical contributes to measurement uncertainty: random and systematic effects and measurement accidents (outliers) 1.2 Metrological characteristics Relationship between uncertainty contributes and instrument characteristics (bias, repeatability, resolution) and measurement complex (reproducibility, considering instrument, operator, ambient conditions and measurand). 2 Stages of uncertainty evaluation Theoretical basis: theorem of the central limit 2.1 Modelling the process Use of theoretical or empirical models to identify the measurement procedure: correlation uncertainty (ISO GPS Standards) 2.2 Evaluation of uncertainty Type A and Type B uncertainty contributes (ISO GUM) 2.3 Determining expanded uncertainty Uncertainty propagation and relevant degrees of freedom 2.4 Critical points Independent variables correlation, non linearity, asymmetry of probability distributions 3 Uncertainty table Practical method for evaluating uncertainty 4 Typical examples Applications to case studies on measurement, mechanical design and production process planning

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Course organizer
Guido
Place/Venue
Anker Engelunds Vej 1
City
2800 Kgs. Lyngby
Country
Denmark
Workload
2.5
Link
http://kurser.dtu.dk/course/41792