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Finding Mass using Force Sensor DAQ usb 6366

 Hello Everyone,

Need some verification with daq program.

I have one force sensor that connectd with my usb daq device. with this force sensor, unknown object is connected(hanging) and i want to find the mass of this object (F=ma) so i am taking continous sample and generate waveform graph. After the scaling, my waveform will be in Newton unit.

my question is: if i take RMS of this waveform(1d Array data point) and divide by g (9.8 m/s2) then whatever value come is my correct mass? (F=ma).

Thank you in advance

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Hi Gab008,

the RMS VI indeed takes the "Root Mean Square" value of your force measurements. This is an averaged value of all your force measurements, and after the conversion using the acceleration you will get a precise mass (which is probably the desired result in your case). You can find more information about this VI under the following link:

 

RMS VI - LabVIEW 2017 Help - National Instruments
http://zone.ni.com/reference/en-XX/help/371361P-01/gmath/rms/

 

Here is a more detailed, mathematical explanation of it:

 

Root mean square - Wikipedia
https://en.wikipedia.org/wiki/Root_mean_square

 

Kind regards,

Eric H.

Applications Engineer - National Instruments

Eric H.
Applications Engineering
National Instruments
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Hello,

I dont think so i got right value because actual weight of my system is ~400 g but my daq program giving me a strange value (like 40g, 29g, etc..). if i read more sample than some time this value increase.

anyone has an idea?  why this happen for stable mass system hanging with spring ?

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I took again a look at your screenshot and I am wondering how you created this DAQmx task. Are the "raw measurements" you get in NI MAX plausible? Are they in LabVIEW before taking the RMS value of it?

In your RMS VI I can see a coercion dot. I would suggest to use a proper, manual conversion using "Get Waveform Components":

Conversion.png

Eric H.
Applications Engineering
National Instruments
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yeah, raw measurement is right. may be the piezoelectric sensor is the problem because it mainly measure dynamic force and i am measuring static force.

 

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