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

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

3. 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:

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

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

6. Capacitive spring based

7. Capacitive finger

8. Piezoresistive accelerometer

9. Piezoresistivt akselerometer 2

10. Potentiometric level sensor

11. Tilt sensors

12. 2D tilt sensor

13. Linear variable differential transformer LVDT

14. Eddy current sensor

16. Termisk masse (luft) http://www.memsic.com/memsic/products/technology.html

17. Permanant magnet - Hall sensor

18. Permanent field 1

19. Permanent field 2

20. Position sensitive detector

22. Linear -> Rotary

23. Position encoders

24. Ultrasound time of flight

25. Impedance matching

26. Magnetic velocity measurement