So I want to measure a Distance between two points every 0.5 sec with an accuracy of +-0.1mm. These Points get pulled appart each other (only one part moves the other is fixed) in a very slow rate (max 0.5mm/sec). I searched for multible sensors, but they where either to inaccurate or to expensive!
So my Idea was to have an wire with a defined resistance and make an "Potentiometer Design". This wire is attached to two fixed points. On the moveable part I attache some kind of "wiper". On the wiper and on one End I would attache 5V and Analog from the Arduino (I know that I would need a reference Resistor and the Setup would be a bit diffrent). Then when it moves the resistance should change and I would be able to match it with a distance in a look up table.
The distance ranges from 15cm to 30cm;
Now my questions:
Is this Idea realistic?
Which kind of wire is suitable?
Is there a module for this accuracy of distance Measurments?
Or is there a better Sensor out there for this problem?
This is actually how the original Wheatstone bridge worked - one arm of the bridge was a wire slider potentiometer, the other the potential to be measured.
It requires fairly low impedances to work, ie a few volts and a few amps, and wire with stable resistance
as it heats up like nichrome, constatan, manganin.
The measurement can be very accurate as drawn wire is very consistent in its properties over length.
Carbon track pots are hopelessly inaccurate by comparison.