Download Micrometers Vernier caliper

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Electric machine wikipedia , lookup

History of electric power transmission wikipedia , lookup

Spark-gap transmitter wikipedia , lookup

Rectifier wikipedia , lookup

Mains electricity wikipedia , lookup

Voltage optimisation wikipedia , lookup

Buck converter wikipedia , lookup

Ignition system wikipedia , lookup

Resistive opto-isolator wikipedia , lookup

Inductor wikipedia , lookup

Magnetic core wikipedia , lookup

Coilgun wikipedia , lookup

Alternating current wikipedia , lookup

Transformer wikipedia , lookup

Switched-mode power supply wikipedia , lookup

Tesla coil wikipedia , lookup

Metadyne wikipedia , lookup

Rotary encoder wikipedia , lookup

Resonant inductive coupling wikipedia , lookup

Opto-isolator wikipedia , lookup

Transcript
Motion Sensors
Displacement, velocity and acceleration
1
Dimensional measurement
Micrometers
Vernier caliper
•
•
•
One complete revolution = 0.5 mm (usually)
With 50 divisions, each division movement
corresponds to 0.01 mm
If user can control every one-fifth of a
division, a resolution of 0.002 mm is possible
2
Height & depth measurement
Gauge blocks
Dial gauge: typical resolution 0.01 mm
Height & depth gauges
3
Resistive potentiometer
Linear potentiometer
Rotary potentiometer (a) circular; (b) helical
Types: wire-wound, carbon-film and plastic-film (according to resistance element)
4
Linear Variable Differential Transformer (LVDT)
•
•
•
•
Inductive displacement sensor.
Transformer with 1 primary & 2 secondary coils, connected in series opposition
Output voltage (difference between induced voltages) is proportional to core
displacement
Zero reading when core is centered
Primary
Secondary
Rotary differential transformer
5
Eddy current sensor
•
•
•
•
•
Inductive displacement sensor.
Coil is excited at high frequency (typically 1 MHz)
This induces eddy current in the target
Eddy current alters the inductance of the probe coil
This change can be translated into a voltage proportional to the air gap
6
Piezoelectric transducers
• A piezoelectric material generates charge when deformed
• Induced charge leaks away with time
• Piezoelectric transducers are not suitable for static or slowly-varying dispalcements
7
Optical encoders (incremental)
• Measure instantaneous angular position of a shaft
• Output is in the form of pulses to be counted
8
Optical encoders (coded-disc)
• Output is in the form binary numbers to give absolute measure of shaft position
Float encoder
9
Other rotational motion sensors
• Gyroscopes
• Tachometers
• Mechanical flyball
Gyroscope
Photoelectric tachometer
10
Mechanical flyball
Vibration Measurement
11
12
13
14
15
Energy Harvesting
Source: J.K. Ward and S. Behrens, “Adaptive learning algorithms for vibration energy harvesting”,
Smart Materials & Structures 17 (2008) 035025 1-9.
16
Vibration-based Energy Harvesting
Source: B.P. Mann and N.D.Sims, “Energy harvesting from the nonlinear oscillations of magentic
levitation”, Journal of Sound and Vibration (2008) in press.
17
18
19