Linear Position Sensor Terminology

Hysteresis, resolution, repeatability, non-linearity, null-point, temperature coefficient, accuracy.  These are but a handful of the many terms associated with linear position sensors.  To the uninitiated, it can be rather daunting.  And, unfortunately, there is a lot of room for ambiguity and confusion.

For example, let’s take a look at the term “accuracy”, as in “how accurate is this this linear position sensor?”  It seems like a fairly straightforward
question, right?  But in reality, it’s not that simple.   Whenever I get asked that question, my response is “what do you mean by accuracy?”  To which, I usually get a response something like “what do you mean what do I mean by accuracy?”  The fact is that the term “accuracy” means different things to different people.   The person asking the question may want to know the absolute straight-line, absolute positional accuracy (non-linearity) of the sensor.  Or, they may be referring to how accurately the sensor can repeat the same indicated value at the same position over subsequent moves (repeatability).  Or, perhaps what they’re really interested in is the smallest amount of position change that the sensor can detect (resolution).  So, as you can see, it’s not a simple question after all.

An in-depth discussion of linear position sensor terminology could fill numerous pages.  But, thankfully, there are resources available that can be used as a quick reference for some of the most commonly encountered terminology.  One quick, downloadable, reference can be found here.

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