Flexiforce sensors LabView Program

[mecheng16]

Hello, 

I'm working on a student project and we need to measure the load output of a flexiforce sensor. I have a decent amount of experience with labview, wheatstone bridges, and strain gauges, but none with op amps and force sensors. LabView just recommends using theur DAQAssist module but I have a feeling it won't just go as smoothly.

Do we need to have a similar wheatstone bridge and bridge balancing system that you need for strain gauges? Or can I simply use the single channel DAQ assist that LabView recommends? I've also heard various things about modeling opamps in LabView, is this reliable and accurate?

Here is the basic circuit the force sensor company recommends.

Even any help pointing me in the right direction is greatly appreciated.

Thanks

[Hatef.fouladi]

Is it Rosset or single strain gauge sensor ?
for single you have to select on of the bridges for your circuit that labview present in his help for single strain gauges also you have to care about your resistance (your wire should be standard for this propose
but for Rosset strain gauge labview vi would not work you have to make your own code by related formula I had write it before and I can send you if you want with this kind of strain gauge you can calculate stress too just need young module of materials

[RavensFan]

Not true at all.  LabVIEW can work with any kind of strain gage setup whether it is a single gage for a 1/4 bridge, two gages in a half bridge configuration, or 4 in a full bridge arrangement.

What is important is the DAQ equipment you are going to use to read the transducer, or whether you need any signal conditioning circuit prior to whatever signal conditioning is already in the DAQ device,

Hatef, please be careful about spreading misinformation.

[Hatef.fouladi]

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@RavensFan wrote:

Not true at all.  LabVIEW can work with any kind of strain gage setup whether it is a single gage for a 1/4 bridge, two gages in a half bridge configuration, or 4 in a full bridge arrangement.

What is important is the DAQ equipment you are going to use to read the transducer, or whether you need any signal conditioning circuit prior to whatever signal conditioning is already in the DAQ device,

Hatef, please be careful about spreading misinformation

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HI RavensFan,
I do not think we are allowed to  just use Convert Strain Gauge Reading VI for Rosette Strain Gauge and we have to convert data of strain based of  three angle of rosette sensors  . if I want to make short what i means maybe this link could help Rosette Strain Gauge
also as I remember (but i am not sure)  we have to use 24bit DAQ for Rosette
could you give us more information if I am wrong I will be thanks about it 

[mecheng16]

Thanks for the help Ravensfans and Hatef

The DAQ I'm using is an NI USB-6229 BNC, which as I understand is a purely analog DAQ (?) so I would need a signal conditioning circuit (which would be the op amp?). Again not an expert here.

[Hatef.fouladi]

AS I know if you want have full precision of strain gauge your daq is not good one to use because it is 16 bit and you have to use 24 bit daq
also using signal conditioning circuit or not is relate to your project and length and type of wiring and cables and some other parameter like that
also based on your project maybe USB-6229 could work for example if you want to just announce existence of cracks in your setup device
I should confess that I am beginner in this science and it is better to ask some other friend like RavensFan and other experts to involve in your question

[Dennis_Knutson]

Build the board per the vendor's recommendation or buy their Quick start Board to convert the sensor to a voltage reading. This is the signal conditioning that you need. All of the comments about rosette and 16 bit versus 24 appear to be just noise.

[mecheng16]

Dennis_Knutson thank you, 

so this circuit they recommend is the signal conditioning. So this combined with a fairly simple VI and the DAQ will allow me to do what I need?

[RavensFan]

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@Hatef wrote:

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@RavensFan wrote:

Not true at all.  LabVIEW can work with any kind of strain gage setup whether it is a single gage for a 1/4 bridge, two gages in a half bridge configuration, or 4 in a full bridge arrangement.

What is important is the DAQ equipment you are going to use to read the transducer, or whether you need any signal conditioning circuit prior to whatever signal conditioning is already in the DAQ device,

Hatef, please be careful about spreading misinformation

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HI RavensFan,
I do not think we are allowed to  just use Convert Strain Gauge Reading VI for Rosette Strain Gauge and we have to convert data of strain based of  three angle of rosette sensors  . if I want to make short what i means maybe this link could help Rosette Strain Gauge
also as I remember (but i am not sure)  we have to use 24bit DAQ for Rosette
could you give us more information if I am wrong I will be thanks about it 

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First, when you mentioned rosette's I was picturing the kind where you have two gages 90 degrees apart in orientation that are meant to read shear strain from torque, or possible the tensile strain and poisson strain.  See the link here,  http://www.vishaypg.com/micro-measurements/stress-analysis-strain-gages/all-shear-torque-rosettes/  Those can be wired into a bridge and used with a DAQ device that supports strain gage sensors.

With the link and image you are showing, where there are 3 gages as various orientation,  0,60,120 or 0, 45, 90, then you are correct you need to read each of those gages separately and do the math in LabVIEW.  The link you posted has a VI that does that math for you which means there really isn't a lot of additional work the programmer needs to do.

All of this is a moot point for the original poster's question, and is just a distraction from the problem he is trying to solve.  Nothing in his messages indicates he has a rosette-type of strain gage.

PS.  You do not need to you a 24-bit DAQ for rosette.  You just need to use what bit-level of DAQ device that will give you the accuracy and resolution you need.  That is true of rosettes, single strain gages, or any other type of sensor input you are trying to read.

[Dennis_Knutson · Accepted solution]

mecheng16,

Yes, the signal conditioning they provide will convert the change in resistance of the sensor to a voltage that can be read by the DAQ card.