Looking for information about non-linearity of sensors

[patrick]

Non liearity of sensors

Hi there,
Can someone please help me to know more about a sensor's non linearity. I dont know a specific sensor, but I think there must be some sensors that are not linear, even within their specification range!!!!
Also, could you please tell me what techniques of dealing with non linearity?
Thanks alot
Patrick

 

[jetset]

Re: Non liearity of sensors

You can try using a deflection bridge. You have to get the non-lineal characteristic of your sensor, then you can chose min a max points in this curve to trace an "Ideal" linear characteristic. And then replace the min, middle and max values of your Ideal characteristic in the bridge equations and then you solve to find the values of the resistances and voltage for your bridge. And if you do it well you have to get a linear voltage in the output of the bridge.

 

[veer]

Re: Non liearity of sensors

hi,

i am working with oxygen sensors ,they have different responses over different range.

Since there are different ranges ,we use piecewise integration and then fit the curve.

i am too searching for a better procedure for the non linearity removal.

hope this helps.

bye,
veer.

 

[kenawy]

Re: Non liearity of sensors

Hi there,
Can someone please help me to know more about a sensor's non linearity. I dont know a specific sensor, but I think there must be some sensors that are not linear, even within their specification range!!!!
Also, could you please tell me what techniques of dealing with non linearity?
Thanks alot
Patrick

ther are many types of sensors i use a pressure sensor " load cell " you can control the reading of the sensor by AD converter input to a microcontroller then u can do any thing in the reading of the sensor
best regards

 

[mrcube_ns]

Re: Non liearity of sensors

I suppose (this is microcontrollers group) that you use mcu, and that you use some kind od A/D (inside mcu or outside mcu no matter).

There are two ways to do linearisation :
1. You can write function for incomming A/D data e.g.
if (A_D_in < 0x0FFF){
AD_linearised = A_D_in + 123; // e.g. difference is 123 non linear
}
else if (A_D_in < 0x6F5G){
AD_linearised = 2*A_D_in - 23;
}
....

2. Write table of caracteristic values (V1, V2, V3, ...), and if measure is between two one just (e.g. between V2 and V3), you make line between those two points (basic mathematical formula y=ax+b), and get value for specific measurement.


Mr.Cube