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Sensors and Actuators Chapter 4 ME 392 February 13, 2012 week 5

Sensors and Actuators Chapter 4 ME 392 February 13, 2012 week 5. Joseph Vignola. Sampled Time Histories. Two weeks back we talked about samples time histories . Frequency Spectra. Two weeks back we talked about samples time histories .

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Sensors and Actuators Chapter 4 ME 392 February 13, 2012 week 5

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  1. Sensors and ActuatorsChapter 4ME 392February 13, 2012week 5 Joseph Vignola

  2. Sampled Time Histories Two weeks back we talked about samples time histories

  3. Frequency Spectra Two weeks back we talked about samples time histories And last week we discussed that any time history made up discreet amounts of specific frequency components.

  4. Frequency Spectra Two weeks back we talked about samples time histories And last week we discussed that any time history made up discreet amounts of specific frequency components. The frequency spectrum tells us how much of each frequency is in the time history

  5. Electronic Filter The filter you built is an electronic device that suppress the frequency component above a “cut-off” frequency.

  6. Electronic Filter The filter you built is an electronic device that suppress the frequency component above a “cut-off” frequency. Other filters can be constructed to suppress frequency below a cut-off frequency…

  7. Electronic Filter The filter you built is an electronic device that suppress the frequency component above a “cut-off” frequency. Other filters can be constructed to suppress frequency below a cut-off frequency… Or around a frequency

  8. Electronic Filter The filter you built is an electronic device that suppress the frequency component above a “cut-off” frequency. Other filters can be constructed to suppress frequency below a cut-off frequency… Or around a frequency Or everything but the spectral content around a specific frequency.

  9. Electrical Transfer Functions By establishing the ratio of the FFTs of the output and input of a circuit we can predict the output of a circuit given an input. Then we can say that for any other input Then we can say that for any other input

  10. Mechanical Transfer Functions Mechanical systems responded to forces or electrical inputs in a way that can be predicted by a transfer function

  11. Sources A loudspeaker converts an electrical signal to a quickly changing pressure field. Taken from www.school-for-champions.com A shaker is a device that is a lot like speaker but outputs a force and is used for shaking things

  12. Other Sources A laser is also a source. Taken from www.gearlive.com An antenna is a source Any device that has an electrical signal input and outputs a related for quantity The related quantity can be a Force Motion Some form of heat Taken from atechfabrication.com

  13. Linear Sources A source is a linear source if there is a simple proportionality that relates the input. Taken from www.wilcoxon.com Often we express the sensitivity as a transfer function This can either be a graph or a number that represents the behavior in a operational band For our speaker maybe something like

  14. Sensors Sensors are used to measure. We will uses Force sensors Accelerometers Strain gauges Pressure sensors But there are all kinds of sensors Taken from www.pcb.com A force sensor creates a voltage proportional to an input force

  15. Sensors Sensors are used to measure. We will uses Force sensors Accelerometers Strain gauges Pressure sensors But there are all kinds of sensors Taken from www.pcb.com An accelerometer creates a voltage proportional to an input acceleration But remember to convert this by multiplying

  16. Sensors Sensors are used to measure. We will uses Force sensors Accelerometers Strain gauges Pressure sensors But there are all kinds of sensors Taken from www.sensorland.com A strain gauge ultimately creates a voltage proportional to strain Strain is dimensionless

  17. Signal Conditioning The hitch with most sensors is that they are not able to produce much (if any) electrical signal on there own. For many sensor we need to use some other device between the sensor and the computer. This could be a Signal conditioner A preamplifier / power supply Wheatstone bridge Taken from www.pcb.com

  18. Signal Conditioning The hitch with most sensors is that they are not able to produce much (if any) electrical signal on there own. For many sensor we need to use some other device between the sensor and the computer. This could be a Signal conditioner A preamplifier / power supply Wheatstone bridge Taken from www.b&K.com

  19. Signal Conditioning The hitch with most sensors is that they are not able to produce much (if any) electrical signal on there own. For many sensor we need to use some other device between the sensor and the computer. This could be a Signal conditioner A preamplifier / power supply Wheatstone bridge

  20. Connectors The connectors we use in the lab are 3.5mm or stereo mini

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