Learning objectives
At the end of the course the student is expected to be able to:
- correctly express a measurement;
- know the International System of Units;
- estimate the measurement uncertainty;
- know the objectives and procedures of static and dynamic calibration of measurement instruments;
- know the main metrological characteristics influencing the performance of a measurement instrument;
- know the concept of transfer function of a measurement instrument and how to estimate the characteristics;
- know the chain of acquisition for Analog-to-Digital conversion of signals and the connected problems;
- know the basic principles of sensors and measurement systems for the measurement of the following physical quantitities: temperature, displacement (relatve and absolute), acceleration, strain, load and pressure.
Prerequisites
Course unit content
Introduction to Metrology. Measurement process. Intensive and extensive quantities. Measurement methods: deviation/zeroing, direct/indirect. Measurement model. Expression of a measurement. Significant digits. Error and uncertainty. Compatibility of measurements. International System of measurement units. Evaluation of uncertainty according to GUM (Guide to the expression of Uncertainty in Measurement). Standard uncertainty (Type A or B), combined uncertainty, extended uncertainty. Monte Carlo Methods for the estimation of uncertainty. Elements of statistics. Static calibration and static properties of measurement instruments. Dynamic properties of measurement instruments. Simple signals and sinusoids. Transfer function. Fourier analysis and frequency domain. Dynamic calibration. Zero order systems, first order systems, second order systems. Acquisition chain of signals. Analog-to-digital conversion. Sampling of signals and aliasing. Quantization of a signal. Filters (ideal and real) and their transfer functions. Configuration of system for single channel and multiple channel acquisition. Trigger: characteristic parameters and its use in the acquisition process. Elements of temperature scales (relative and absolute). Temperature measurements. Thermal expansion methods (bimetallics, liquid-in-glass, pressure). Thermocopules, electrical-resistance sensors, thermistors. Fundamentals of thermal radiation. Broadband radiation thermometers (Pyrometers). Relative displacement sensors. Resistive potentiometers, LVDT, optical encoders (incremental and absolute), capacitance pickups, eddy-current transducers, laser triangulation sensor. Seismic sensors: seismometer and accelerometers. Piezoelectric accelerometers. Strain measuements. Definition of stress and strain in mono-axial case. Resistance strain gauges. Rosette strain gauges. Application of strain gauges. Wheatstoone bridge. Applications: normal stress and bending stress. Temperature effects on strain gauges. Force measurements. Basic methods of force measurements. Elastic force transducers. Bonded strain gauge transducers (load cells): compression, bending and torque. Piezoelectric load cells. Impact hammer with load cell. Pressure measurements. Definition of relative and absolute pressure. Liquid column manometer. Elastic pressure transducers: Bourdon tube, diaphragms and bellows. Membrane with strain gauges pressure transducers. Piezoelectric pressure transducers. Measurement of dynamic pressure.
Full programme
Bibliography
E.O. Doebelin : Measurement Systems: Application and Design Mc Graw Hill
https://www.ceinorme.it/it/normazione-it/vim.html
https://www.bipm.org/en/publications/guides
Teaching methods
Didactic activities are lectures regarding theoretical basis of metrology and basic principles of measurement instruments. Theoretical lessons are supported by guided practice, analysis and visualization of data with MATLAB. Slides as support for lectures will be weekly uploaded on Elly platform. To download the slides, enrolment to the course is mandatory. Slides are considered part od didactic material. It is worth remembering to non-frequenting students to check information and materials provided on Elly. The professor is available for clarifications about the lectures by appointment (via email).
Assessment methods and criteria
The exam is written and consists of a series of closed or open questions. The duration of the test is 1,5 hours. The evaluation is done with the scale 0-30. The honor is assigned if the maximum score is obtained in all the questions. Online registration to the exam is MANDATORY. For possible partial tests a list will be opened on Elly.
Other information
