Download ME 106 Signal Sources

Signal Sources
B. Furman
31JAN2013
Mechatronics Concept Map
Power
Source
User
Interface
ME 106
ME 120
Controller
(Hardware & Software)
ME 106
Power
Interface
Signal
Conditioning
INTEGRATION
ME 106
ME 154
ME 157
ME 195
ME 106
ME 190
ME 187
ME 106
ME 120
Actuator
Sensor
ME 120
ME 297A
System to
Control ME 110 ME 182
ME 136 ME 189
ME 154 ME 195
ME 157
BJ Furman 15JAN11
Signal Sources - 1

Signal source concept

Sensors as an information source

Their output voltage or current level encodes
information about the quantity to be measured


Most often information is encoded as a voltage
level


Ex. The voltage output from a Wheatstone
bridge
 The information: weight on the scale
encoded as a voltage
Current level also used


Remember the dishwasher light sensor example?
 Output voltage proportional to intensity of
light
4 – 20 mA commonly used in industrial
controls
Signals to power interface
Signal Sources - 2

Sensor data sheets
 ADXL203

Precision ±1.7 g dual-axis
accelerometer


Can use also to sense tilt
 iPhone display
1000 mV/g sensitivity


http://www.analog.com/static/imported-files/data_sheets/ADXL103_203.pdf
17mg/deg from
horizontal
17 mV/deg tilt
Horizontal
Tilted
mgsin(q)
force
component
Dx
q
mg
Slope=sensitivity
Sine
function
Signal Sources - 3
Vout

Ideal signal source



Ideal voltage source
No output impedance
1V/g
Input quantity
Practical signal source





Relatively low-level output
Finite output impedance
Prone to noise
Zero offset
noise
Non-linear
1V/g
Vout
Ro
Input quantity