Sensor and Actuator system
～Signal processing～
Dr. Jun ISHIMATSU
2
Sensor and Actuator system
SMJP4333 / 2016-2017-2
Data flow
Display /
Indicator
Human
Target
Quantity
Sensor
Analog
Process
A/D
Conversion
Data store
Digital
Process
Signal Processing
Analog Controller
D/A
conversion
Digital Controller
ANALOG PROCESS
Analog processing
• Amplifier
– OP-Amp
• Addition / Subtraction
– Differential
– OP-Amp
• Filter
– CR
– OP-Amp
Ideal Op Amp
• A differential input, single output amplifier, infinite gain.
• High input impedance (MΩ) but low output impedance (<100Ω).
• Active devices (require ± 15V)
741 Op Amp chip
• Eight-pin dual in-line package (DIP).
• The input impedances, bandwidth, and power ratings can vary
significantly (refer data sheets).
741 internal design
Inverting Amplifier
• Connect two external resistors to an op amp to invert and amplify
the input voltage.
• The feedback loop with RF implies negative feedback.
Non Inverting Amplifier
Vo  (1 
Rf
R1
)V1
Summer Op Amp
• Used to add analog signals
• The circuit output is the negative sum of the input
Difference Op Amp
• Used to subtract analog signals
High resolution register
• Normal carbon register: 4 lines
• High resolution(High accuracy) : 5 or 6 lines
Instrumentation amplifier
 For what?
𝑉𝑜𝑢𝑡 =
𝑅4
𝑅2
1+2
𝑅3
𝑅1
𝑉2 − 𝑉1
Filter
• Signal is periodic
1
𝑓 𝑡 = 𝐴0
2
+
∞
𝐴𝑛 cos 𝑛𝜔0 𝑡 + 𝐵0 sin 𝑛𝜔0 𝑡
𝑛=1
=
– L.P.F. (Low Pass Filter)
– H.P.F. (High Pass Filter)
– B.P.F. (Band Pass Filter)
– B.E.F. (Band Elimination Filter) / B.S.F.(Band Stop…)
Cut-off frequency
https://en.wikipedia.org/wiki/Low-pass_filter
L.P.F.
• Using Capacitor and Registor
𝑓𝑐 =
1
2𝜋𝑅𝐶
• Using OP-Amp
𝑓𝑐 =
R1?
1
2𝜋𝑅2 𝐶
H.P.F.
• CR circuit
𝑓𝑐 =
1
2𝜋𝑅𝐶
• OP-Amp circuit
𝑓𝑐 =
1
2𝜋𝑅1 𝐶
A/D CONVERSION
Introduction
• Consider a signal from a sensor as illustrated by the analog
signal in figure.
Analog signal & sampled equivalent
• A continuous voltage range is divided into discrete output states,
each of which is assigned a unique code.
Analog-to-digital conversion
Terminology
• F.S.R. (Full Scale Range)
– F.S.R. = (Max – Min)
• n-bit conversion
– 0~2n (e.g. 10bit = 0~1023, 16bit = 0~65535)
• L.S.B. (Least Significant Bit)
– L.S.B =
𝐹.𝑆.𝑅.
2𝑛 −1
Bi-polar / Uni-polar
Bi-polar
• ±5v, ±10v……
+F.S
Uni-polar
• 0-5v, 0-10v, 1-5v
F.S.
Max
Min
-F.S.
0
0
error
Voltage / Current
Voltage
Current
• Many kinds of Range
• Mostly 4-20mA
– 0-5v, -5~+5v……..
– 250Ω of register is necessary
• Widely used
• Limited to use
• Weak against Noize
• Tough against Noize
Voltage output
S/N ratio = 1:1
Current output
S/N ratio = 1:0.001
Usually Impedance of Device is 1~5MΩ
25
Single-end & Differential
• Single end input
A/D Converter
AI1
• Differential input
A/D Converter
AI1
Ai1-Ai2
AI2
2015/6/26
http://www.contec.co.jp/product/device/analog/basic.html
TriPreM Rinkoh
Connector information
• 1 input – 3wire
• Sequence is NOT important
(some board configurarable)
27
Multi-Plexor
• Multi plexor type
Plexor
ADC
t
• Multi ADC type
ADC
ADC
t
2015/6/26
TriPreM Rinkoh