Instrumentation for Engineers and Scientists

by Turner, John; Hill, Martyn

• ISBN13: 9780198565178
• ISBN10: 0198565178
• Format: Paperback
• Copyright: 1999-05-27
• Publisher: Oxford University Press

Summary

This book was developed from material prepared for a course in instrumentation for final year mechanical engineering undergraduates. The approach used is to present instrumentation from the viewpoints of both electronics and signal analysis. The sensors and electronic circuits likely to be needed by a final year student project and for postgraduate research, are comprehensively covered. It forms a suitable degree-level text for students of engineering, science or medicine seeking a practical guide to instrumentation. It is also hoped that the book will be of use to practising engineers in general. The authors' aim throughout has been to write a book which guides the reader through the intricacies of specifying and selecting an instrumentation system, acquiring data without corrupting or distorting it in the process, and applying sensible signal analysis techniques. Examples and case studies are used to illustrate the techniques discussed, including many drawn from real-life instrumentation problems encountered by the authors in engineering, physics and medicine. The sequence of chapters follows the flow of data from the primary sensing element, through transduction, signal processing and digital conversion to digital signal analysis techniques. This logical sequence ensures that the design process is undertaken in the correct order, and provides continuity for the reader.

Table of Contents

General design of instrumentation systems---error analysis
Introduction	1	(2)
Generalized instrumentation design	3	(2)
Error analysis and the performance of a measurement system	5	(6)
Random errors	6	(1)
Systematic errors	7	(1)
Indirect measurements	8	(2)
Combining errors on sums, differences, products, and exponentials	10	(1)
Conclusions	11	(1)
Temperature sensors
Introduction	12	(2)
Resistive temperature transducers	14	(4)
Metallic resistive temperature sensors	14	(1)
Thermistors	15	(2)
Resistance temperature sensor bridge circuits	17	(1)
Thermocouples	18	(4)
Thermocouple compensation	19	(2)
Multiple thermocouple arrangements	21	(1)
Bimetallic temperature sensors	22	(1)
PN junction sensors	23	(1)
Liquid crystal temperature sensors	24	(1)
Infra-red emission and pyrometry	25	(1)
Heat flux gauges	26	(1)
References	27	(1)
Displacement sensing
Introduction	28	(1)
Potentiometers	28	(4)
Potentiometer linearity	28	(2)
Potentiometer resolution	30	(1)
Electrical noise problems in potentiometers	31	(1)
Inductive displacement transducers	32	(5)
Variable reluctance transducers	32	(2)
Variable coupling transformers: LDTs and LVDTs	34	(3)
Eddy current displacement transducers	37	(1)
Capacitive displacement transducers	37	(3)
Linearity of capacitive displacement transducers	39	(1)
Optical motion sensors	40	(2)
Angular optical encoders	41	(1)
Translational optical encoders	42	(1)
Ultrasonic displacement transducers	42	(2)
Hall effect motion sensors	44	(3)
Hall probe rotation rate sensors	45	(1)
Hall probe displacement measurement systems	45	(2)
References	47	(1)
Velocity and acceleration transducers
Introduction	48	(1)
Accelerometer and seismometer theory	49	(5)
Seismometers	50	(1)
Accelerometers	51	(1)
Phase distortion in accelerometers	52	(1)
Accelerometer resonance frequencies	53	(1)
Longitudinal velocity sensing	54	(1)
Rotational velocity sensing	55	(1)
Accelerometer designs	55	(16)
Piezoelectric accelerometers	56	(1)
The piezoelectric effect	56	(1)
Piezoelectric accelerometer designs	57	(2)
Frequency response of PE accelerometers	59	(1)
Cross-axis (transverse) sensitivity of PE accelerometers	59	(1)
Piezoresistive accelerometers	60	(1)
Analysis of piezoresistance	61	(1)
Silicon piezoresistive (PR) accelerometers	62	(1)
Resonance frequency	63	(1)
Sensitivity of silicon accelerometers	63	(1)
Off-axis modes and transverse sensitivity	64	(1)
Thick film piezoresistive accelerometers	65	(1)
Capacitive accelerometers	66	(1)
Environmental effects on accelerometers	67	(1)
Thermal sensitivity of accelerometers	68	(1)
Humidity	69	(1)
Acoustic sensitivity of accelerometers	69	(1)
Base strain sensitivity	69	(1)
Electromagnetic interference (EMI) and accelerometers	69	(1)
Accelerometer mounting techniques	70	(1)
Accelerometer connecting cables	70	(1)
References	71	(1)
Strain measurement techniques
Introduction	72	(1)
Wire and foil strain gauges	72	(3)
Semiconductor strain gauges	75	(1)
Thick film strain gauges	75	(1)
Strain gauge transducers	75	(2)
Bridge circuits for strain gauge transducers	77	(12)
Bridge balancing	78	(1)
The quarter bridge	79	(2)
The half bridge	81	(3)
The full bridge	84	(2)
AC bridges	86	(3)
Summary	89	(1)
References	89	(1)
Pressure sensors
Introduction	90	(2)
Elastic pressure sensors	92	(8)
Bourdon tubes	93	(1)
Bellows	94	(1)
Diaphragms and membranes	94	(4)
Diaphragm pressure sensor fabrication techniques	98	(2)
Capacitance pressure sensors	100	(4)
Capacitor microphones	102	(2)
Pressure swiches	104	(1)
Pressure sensor environmental considerations	105	(4)
Chemical attack	105	(2)
Over range effects	107	(1)
Pressure sensor acceleration sensitivity	107	(1)
Thermal sensitivity of pressure sensors	108	(1)
References	109	(1)
Torque and mechanical power measurement
Introduction and definitions	110	(2)
Mechanical methods of torque measurement	112	(3)
Strain gauge torque transducers	115	(2)
Torsion bars	117	(4)
Non-contact magnetic methods	121	(1)
Surface acoustic wave (SAW) torque transducers	122	(1)
References	123	(2)
Flow sensors
Introduction	125	(1)
Vector flow transducers	125	(3)
Hot-wire and hot-film flow transducers	125	(2)
Pitot tube flow sensors	127	(1)
Volume flow sensors	128	(2)
Orifice plates	128	(1)
Turbine flowmeters	129	(1)
Rotameters	129	(1)
Laser Doppler and correlation flow transducers	130	(2)
Ultrasonic flowmeters	132	(1)
Vortex shedding flowmeters	133	(1)
References	134	(1)
Signal conditioning circuits
Introduction	135	(2)
Operational amplifier circuit basics	137	(1)
Analysing operational amplifier circuits	138	(4)
Example use of op-amp rules	139	(1)
Example 2	140	(1)
Example 3	141	(1)
Frequency response and gain-bandwidth product	142	(1)
The op-amp's departures from idea behaviour	143	(4)
Common-mode interference	144	(1)
Voltage supply rejection ratio (VSRR)	145	(1)
Input offset voltage (IOV)	145	(1)
Input bias current	146	(1)
Slew rate	146	(1)
Inverting and non-inverting circuit input impedances	147	(1)
Operational amplifier circuit selection	147	(1)
Common operational amplifier circuits	148	(14)
The inverting amplifier	148	(1)
The non-inverting amplifier	148	(2)
AC amplifiers	150	(1)
The constant current source, or voltage/current converter	151	(1)
Summing amplifiers	152	(1)
Differential amplifiers	152	(1)
Filter circuits	153	(1)
Low-pass filter	154	(1)
High-pass filter	155	(1)
Band-pass filter	155	(1)
Bandstop filter (notch filter)	156	(1)
The precision rectifier	156	(1)
The integrator	157	(1)
The differentiator	158	(1)
The comparator	159	(1)
Current to voltage converter	160	(1)
The charge amplifier	160	(2)
References	162	(1)
Signal conversion and data acquisition
Introduction	163	(1)
Analogue to digital conversion	163	(5)
Quantization errors	165	(3)
Computer-based data acquisition	168	(2)
References	170	(1)
Signal analysis---frequency domain techniques
Introduction	171	(1)
The Fourier series	172	(3)
The Fourier transform	175	(2)
Digital frequency analysis---the discrete Fourier transform	177	(1)
Sampling and aliasing	178	(3)
Windowing	181	(5)
References	186	(1)
Index	187