1. INSTRUMENTASI INDUSTRI

2. Instrumentation System
A Measuring system is required to compare a quantity with a standard or to provide an output that can be related to the quantity being measured
The quantity to be measured is detected by an input transducer or sensor.
The detected quantity may be converted to a mechanical or electrical form of energy
Input
Output
Display
Signal
conditioner
Sensor
Recorder
Measurand

3. Instrumentation System
Control and feedback
Power source
Sensor
Perceptible output
Primary sensing element
Variable conversion element
Signal processing
Output display
Measurand
Calibration signal
Data storage
Data transmission
Radiation, electric current, or other applied energy
Dashed lines are optional for some applications

4. Blood Pressure Instrument
Clinical Instrument
Black box
Need many kinds of Instruments
Expensive
Clinical Instrument
Blood Pressure Instrument
．．．．．．
EMG Instrument
ECG Instrument

5. Clinical Instrument (cont.)PC
surface electrode pressure transducer photocoupler temperature sensor pressure gauge
strain gauge ：
A/D Converter
LCD
Sensor
Process Circuit
Oscilloscope

6. Definitions Measurand (Physical quantities): Sensor:
Position, displacement
Temperature
Force
Pressure,…
Concentrations, chemicals,…,
Sensor:
is a device that detects a change in a physical stimulus and turns it into a signal which can be measured or recorded
Signal conditioning:
Amplifying, wave shaping, filtering, rectifying,…
Transducer:
is a device that transfers power from one system to another in the same or in a different form.

7. Purpose of Measurement Systems
Process, machine or system being measured
Observer
Input
True value of variables
Measurement
System
Output
Measured value of variables
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Lecture 2

8. Measurement Theory
Measurement is a mapping of a source set in the empirical domain space onto an image set in the abstract range space.
States of
process or
system
Curves or
values
Empirical Space
Abstract Space
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9. Essential Requirements
Descriptive
provide relationship between output and state.
Selective
provide desirable information only.
Objective
be independent of arbitrary observers.
Validated
represent the true value.
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10. Types of Measurements Manufacturing measurements
discretely monitoring products quality.
Performance measurements
providing performance evaluation as needed.
Operational measurements
continuously monitoring operation process.
Control measurement
continuously providing feedback signals.
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11. Essential Elements Measurement System Input Output Sensing Element
True value of variables
Measurement
System
Output
Measured value of variables
Sensing Element
Conditioning Element
Processing Element
Displaying Element
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Lecture 2

12. Sensing Elements In contact with the information carrier or medium
Giving a signal output related to the quantity being measured
Examples:
strain gage, R depends on mechanical strain;
thermocouple, V depends on the temperature;
LVDT, L depends on the displacement.
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13. Signal Conditioning Elements
Prepares sensor outputs suitable for further processing.
Mostly use various conditioning circuits.
examples:
deflection bridge, converts an impedance change into a voltage change
amplifier, amplifies millivolts to volts
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Lecture 2

14. Signal Processing Elements
Converting conditioned output into forms more suitable for presentation.
Calculating secondary variable from measurable variables.
Examples:
analog-to-digital converter
analog or digital filter
signal compensation
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15. Data Display Elements
Display and/or store measured signals in recognizable form.
Use of analog and/or digital form.
Examples:
visual display units, like Oscilloscope
analog chart recorders
digital data array
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16. Accuracy and Precision
Precise readings
Accurate readings
True value
Accuracy
deviation of the output from the true value
indicates the closeness of measured and true values
Precision
degree of reproducibility of a measurement
indicates the repeatability of measures values
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17. Definition of Accuracy
Accurate is a property of a complete measurement rather than a single element.
Accuracy is quantified using measurement error:
E = measured valve – true valve = system output – system input
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18. Measurement System Gains
Sensing
Element
Conditioning
Processing
Presentation
True
Value
Measured K1 K2 K3 K4 I O
Gain is defined as the ratio of output to the input.
Each element, as well as the entire system, has its specific gain!
Ideally:
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19. Measurement Error
Sensing
Element
Conditioning
Processing
Presentation
True
Value
Measured K1 K2 K3 K4 I O
None of the elements can be perfectly manufactured and integrated in the system  it results error!
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20. Sources of Measurement Errors
Improper sensing position
Improper element calibration
Improper data acquisition method
Improper sampling rate
Elements non-linearity
Environment effects
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21. Error Reduction Techniques (1)
The most effective method of reducing measurement error is to:
Set the sensing element at the right position.
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22. Error Reduction Techniques (2)
An effective and useful method of reducing measurement error is to:
Calibrate each element to eliminate or reduce bias.
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23. Error Reduction Techniques (3)
Another effective method of reducing measurement error is to:
Setup a proper sampling rate for data acquisition. D
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24. Error Reduction Techniques (4)
An effective and useful method of reducing measurement error is to:
Compensate sensing element non-linearity. I U C
U(I)
C(U) U C C I U I
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25. Error Reduction Techniques (5)
Another effective method of reducing measurement error is to:
compensate the environmental effects
Environmental effects isolation:
Environmental input cancellation:
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26. Part II: Learn from Example
Assume a temperature measurement system was used to monitor the temperature in this classroom. This measurement system uses a thermocouple (gain: 40 V/C) as its sensing element, a signal amplifier (gain: 1 V/mV) as its signal conditioning element, and a visual indicator (gain: 25 C/V) as its display element. Please try to:
Design the measurement system, and present the design using a system block diagram.
Determine the gain of the measurement system.
Estimate the measurement error if the thermocouple gain is V/C, the amplifier gain is V/mV, and the indicator gain is C /V.
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Lecture 2

27. KARAKTERISTIK PENGUKURAN