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I
Instrumentation and Measurement Concepts
1 Measurements, Instrumentation, and Sensors Halit Eren
Introduction
Measurements
1.3 Instruments
Analog and Digital Instruments
Sensors and Transducers
Instrumentation and Networks
Software Support for Sensors and Instruments
Application Examples
Bibliography
Partial List of Vendors and Suppliers
2 Characteristics of Instrumentation John R. Hansman, Jr.
Simple Instrument Model
Bibliography
3 Operational Modes of Instrumentation Richard S. Figliola
Null Instrument
Deflection Instrument
Analog and Digital Sensors
Analog and Digital Readout Instruments
Input Impedance
Defining Terms
Further Information
5 Measurement Accuracy Ronald H. Dieck
Error: The Normal Distribution and the Uniform Distribution
Measurement Uncertainty Model
Calculation of Expanded Uncertainty
Summary
Defining Terms
References
Further Information
6 Development of Standards Halit Eren
Introduction
Standard Organizations
Development of Standards
Obtaining and Using Standards
Examples of Standards
Software Standards
Bibliography
7 Measurement Standards DeWayne B. Sharp
Historical Perspective
What Are Standards?
Conceptual Basis of Measurements
Need for Standards
Types of Standards
Numbers, Dimensions, and Units
Multiplication Factors
Conversions of Units
Examples of Defining Terms
Bibliography
8 Calibrations in Instrumentation and Measurements Halit Eren
Introduction
Errors and Uncertainties in Calibrations
Benefits of Calibrations
Calibration Procedure and Personnel
Calibration Methods
Laboratories and Institutions
Calibration Software Support
Cost of Calibrations
Trends in Calibrations
Calibration Examples
Bibliography
Partial List of Calibration Service and Software Providers
9 Intelligent Sensors and Instruments Halit Eren Introduction
Intelligent Sensors
The IEEE 1451 Standard
Communications of Intelligent Sensors
Plug-and-Play Capability
Applications and Examples of Intelligent Sensors
Intelligent Instruments
Examples of Intelligent Instruments
References
Bibliography
Partial List of Manufacturers/Suppliers
10 Virtual Instruments David Potter and Halit Eren
Introduction
Virtual Instrument Architecture
Virtual Instrument Software
Supervisory Control and Data Acquisition
Conclusions
Bibliography
Partial List of Suppliers
11 Fail-Safe Instruments and Devices Davide Quatrini, Giuseppe Fazio, Mauro Giaconi, and Adelio Salsano
Introduction
Fail-Safe Realization: Relevant Features
Fail-Safe Realization: In-Depth Example
Case Study: Level 1 ERTMS
Summary
References
12 Dynamic Error Measurements of Force Sensors Akihiro Takita, Jin Tao, and Yusaku Fujii
Introduction
Problems and Solutions of Dynamic Calibrations
Evaluation of Dynamic Characteristics of Force Sensors
Impulse Response
Oscillation Response
Conclusions
References
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1
Measurements, Instrumentation, and Sensors
Halit Eren
Curtin University
1.1 Introduction
1.2 Measurements
1.3 Instruments
Design of Instruments
Testing and Use of Instruments
Response and Drift
Accuracy and Errors
Error Reduction
Calibration of Instruments
1.4 Analog and Digital Instruments
Analog Instruments
Digital Instruments
1.5 Sensors and Transducers
Smart Sensors
Wireless and Autonomous Sensors and Instruments
1.6 Instrumentation and Networks
1.7 Software Support for Sensors and Instruments
1.8 Application Examples
Bibliography
Partial List of Vendors and Suppliers
1.1 Introduction
Measurement is a process of gathering information from a physical world and comparing this information with agreed standards. As highlighted in this chapter and discussed in detail in this book, measurements are essential activities for observing and testing scientific and technological investigations.
Measurements are carried out by using instruments, which are designed and manufactured to fulfill specific tasks. Sensors are used as the primary elements in instruments to respond to the physical variable under investigation. In this book, a diverse range of sensors and instruments are discussed; the advances and the recent developments in measurements, instrumentation, and sensors are introduced in the proceeding sections and chapters.
In many applications, many sensors and instruments are used to collect information about the process under investigation. These instruments are connected together using wired, optical, or wireless networks. The details of the supporting hardware and software technologies behind these networks are discussed extensively.
1.2 Measurements
If the behavior of the physical variable is known, its performance can be monitored and assessed by means of suitable methods of sensing, signal conditioning, and termination. The applications of instruments range from laboratory conditions to arduous environments such as inside nuclear reactors or remote locations such as satellite systems and spaceships.
The sensor-output signals of the majority of modern instruments are in electric form. This is due to electric signals being easy to process, display, store, and transmit. Once converted to electric forms, the relation between the sensor signals and the physical variations can be expressed in the form of transfer functions. The transfer function is a mathematical model between the sensor signal and the physical variable. In a continuous system, the transfer function may be linear or nonlinear. A linear relationship may be expressed by the following equation:
where
y is the electric signal
x is the physical stimulus
a is the intercept on the y-axis, which gives the output signal for a zero input
b is the slope that is also known as the sensitivity
In ideal cases, this relationship should be consistent without any errors, nonlinearity, or deviation.
However, in measurements, there may be many sources of errors; therefore, it is important to identify these sources and draw up an error budget by considering factors, such as
Imperfections in electric and mechanical components (e.g., high tolerances and noise or offset voltages)
Changes in component performances (e.g., shift in gains, changes in chemistry, aging, and drifts in offsets)
External and ambient influences (e.g., temperature, pressure, and humidity)
Inherent physical fundamental laws (e.g., thermal and other electric noises, Brownian motion in materials, and radiation)
Once the measurements are made, various forms of data analysis may be used to extract useful information about the measurements and draw conclusions. Data a...
