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Introduction toMeasurement Systems

References: Measurement Systems

Application and Design 5th EditionErnest O.Doebelin Department of Mechanical Engineering The

Ohio State UniversityPublished by McGraw-Hill

New York, USA. 2004

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Measurement is the operation of

determining the value of a quantity.

Measurement/instrumentation system is themeans used to carry out a measurement.

The field of measurements is rapidly

changing where new Standards,Sensors ,Requirements andMeasurement

systemsare continually being devised

Measurement and Measurement System

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Measurementis an act of assigning a specific value

to a physical variable detected by asensor.

A Measurement sys temincludes all the components

necessary for producing a measurement.

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Measurement system

Measures a physical quantity

Displays result to an operator

and/or

Records result

and/or

Transmits to another system (e.g. a

control system)

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The base of Measurement objectives is from

common language for various systems.

Process _______ Qualitity(Variable)

(event)

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Purpose of measurement system:

MONITORING OF PROCESSES ANDOPERATIONS

CONTROL OF PROCESSES AND

OPERATIONS If you can not measure it,you can not control it .

EXPERIMENTAL ENGINEERING

ANALYSIS COMPUTER-AIDED MACHINES AND

PROCESSES

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Measured objects

Industrial process

Moving objects

One 600,000KW thermal power machine groups:About 800 measurement pointshundreds of instruments

Examples:

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Automobile Electronics

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Normal Car:40-50 sensors

Luxury Car:about 200 sensors

Oil

sensor

Oxygen

sensor

Fuel level

Accelerometer

Seat belt tension

Passenger Occupancy

Wheel speed

Tire pressure monitorRadar sensor

Rain sensor

Parking sensor

Indoor/outdoortemperature sensors

GPS

Water coolant

temperature

Tachometer

SpeedometerOdometer

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ShenZhou Aircraft:near 200 sets of instruments

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Main subjects and topics

Principles of measurement:

Laws and phenomena of natural science:Physics, Chemistry, Biology etc.

for measured variable and measurement methodsone to many

new principles for new sensors developmentMeasurement methods and instruments and equipmentMeasurement engineering

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Measurement Applications

1. Monitoring of processes and operations.

2. Control of processes and operations.3. Experimental engineering analysis

4. Computer-aided machines and processes

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Professional Division:

Metrology():standard, metrical transitivity()

Instrument manufacture

Instrument engineering

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Real-Time Robust

Economy

For Efficiency, Safety, Environmental protection

The eye for production and supervision

Display check, supervision, control and record

New measurement points needed

Multifunctional instrumentation needed

Engineering Measurement

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ScientificMeasurementor Laboratory measurement

Measured objects: studied process orobjects

High precisionspecial variablecombined variables

Display and record

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New trends and applications

Digital instrumentIntelligent or smart instrument

Miniaturized system or micro-system

Networked

Virtual instrument

Multifunctional

Software instrument

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Class Overview /Objectives

Define generalized configurations and descriptions of

measuring systems.

Describe and perform static calibration of numerous

types of measurement devices.

Select and/or design measurement systems to meet

performance specifications.

Describe the principles and characteristics of the most

common measurement systems for the measurement of

motion, forces and torques, pressure, flow, and

temperature.

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Restated Course Objectives

All measurements have an associated uncertainty (which is

not always known in advance). Engineers / scientists need

to know how to assess this uncertainty.

All instruments have a finite range of application. It isimportant to select the best instrument for the task at

hand. (Sensitivity, Bandwidth, Cost, Reliability)

Most real measurements involve determination of multiple

variables, each with its own associated uncertainty.

How do we assess the TOTAL measurement error?

How do we assess the probability of component failure?

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Reference Textbook

Part 1

Part 2

No Part 3

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Summary

Measurement and Measurement systems

Engineering Measurement and Laboratorymeasurement

New Measurement Systems

Courses Objectives

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Assignment

(

Review Ch1 (P3-10)