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|Linearity in measuring sensors
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|Автор:||san [ 09 вересня 2014, 21:54 ]|
|Тема повідомлення:||Linearity in measuring sensors|
Linearity in measuring sensors
Measuring devices that use some sort of electronic or mechanical transducer normally suffer from some level of non-linearity. Is that a problem?
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Linearity in a measuring device reflects the sensor’s ability to respond to changes in the measured variable in the same way across the full range. If you’ve seen old pressure gages, they often have uneven scales where the divisions are larger at one end of the range than the other. This compensates for non-linearities in the flexing of the bourdon tube. The same concept applies to electronic devices, whether they are process instruments such a flowmeters, or discrete devices such as proximity sensors.
Let’s use a temperature sensor as an example. It has to convert a temperature to a corresponding voltage (thermocouple) or resistance (RTD, thermistor). As the temperature changes, the voltage or resistance has to change with it. If a device has high linearity, the amount of voltage or resistance change will be the same per change in temperature across the full range of the device. If you were to plot temperature on one axis of a graph and voltage or resistance on the other, the curve would be nearly straight.
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