Calibrating raw analog sensor values.

[sramirez620]

Hey guys,

new to the foum. Been looking through here and i cant quit seem to be able to find out the solution to my problem.

Little background, I am a Mechanical Engineer, not an electrical engineer, so please give me some slack.

I have 2 sensors that i am trying to calibrate so that i can use them in a labview VI.

Currently i have a very accurate Dwyer PSI gauge that I have connected to my system, 

I thought this would be as simple as pressurizing the system to the max PSI the pump will supply (right around 5 PSI) and then just using a multiplyer to

convert the sensors raw values to the correct PSI values. Guess it is not that simple. When there is no pressure in the system the sensors do not read '0'

I also cannot get them to scale accurately to reflect the Dwyer gauge. Any help would be greatly appreciated my friends. I have attached a picture with more information.

I am currently using a Digilent Chipkit Max32 microcontroller along with Linx.

Just looking for the most simple straight forward way to convert these values.

-Scott

[Henrik_Volkers]

How about a linear function?  y=a + b*x where x is your voltage and y your non SI unit 😉

If you take more than two points pairs (that will be needed to define the two unknown variables a and b)

say X=[x1,x2,x3,x4,...] and Y=[y1,y2,y3,y4,...] , you can apply a linear fit (see LabVIEW help and wikipedia)

Or maybe you find that a higher polynominal fit is even a better transformation ...  (I remember that some resistive bridge pressure gauges where better characterized by a second order function)

However that is no electrical problem, that is engineering 101 (simple math)