1. Acceleration-velocity-position
Outline
Accelerometers
Velocity
Position + Misc!!
Material from
Fraden chap. 7
Fraden chap. 8
Wikipedia
Web
Analog Devices
MEMSIC
SINTEF

2. Position – velocity - acceleration
Oscillatory motion
Position
Velocity
Acceleration
Consequence 1:
low frequency -> measure position or velocity
high frequency -> measure acceleration

3. Consequence 2 Plotting position amplitude emphasizes low frequencies
Plotting acceleration emphasizes high frequencies
Acceleration
Velocity
Fig 3: Bearing damage
Frequency
Velocity is the usual compromise
Frequency
Fig 2: Misalignment

4. Acceleration -> Position
Acceleration is independent of inertial system
Can be measured without reference
Can be measured in a closed container
Position can be found by integrating twice:

5. BUT
=> Measure position if you can
Or, get a grip on your errors

6. Accelerometer approaches
Piezoelectric
Measure F
Compression
Bending
Piezoresistive
Stress/force based
Parallell plate
Comb AC
Capacitive DC FP
(Optical)
Measure x
Cantilever
Fiber
(Magnetic)
Measure v
Inductive
Thermal

7. Capacitive spring based

8. Capacitive finger
Analog Devices

9. Piezoresistive accelerometer

10. Piezoresistivt akselerometer 2

11. Termisk masse (luft)

12. Magnetic velocity measurement

13. Potentiometric level sensor

14. Tilt sensors

15. 2D tilt sensor

16. Linear variable differential transformer LVDT

17. Eddy current sensor

19. Permanant magnet - Hall sensor

20. Permanent field 1

21. Permanent field 2

22. Position sensitive detector

24. Linear -> Rotary

25. Position encoders

26. Ultrasound time of flight

27. Impedance matching

28. Triangulering - GPS
Wikipedia