Non time dependent limit testing

[Bcousins]

Hi

My problem is I have Varying limits that are not time dependent

eg. When angle is -10degrees, the force should be between -8 and -10 N

When the angle is 0 degres, the force should be between -1 and 1 N

When te angle is 10 degrees th force should be beween 60 and 80 N

Assuming linearity, the force should be within those limits throughout the entire angle range.

I do not know how to go about this and have looked at the mask and limit testing

At he moment my program checks for only those specifc points but I need the entire range to be checked

Any help would be greatly appreciated

[tbd]

Hi Bcousins,

      Please correct me if I'm wrong  - is there a set, or sequence, of force measurements where each measurement is associated with a specific "angle"?  Do you want to limit-test each measurement - but the correct limits depend on the specific angle?  If so, I don't think we have enough info. to know what limits to apply to any angles besides the three you mentioned.  I don't understand how to apply "linearity" to this!

A a bit more info about your DAQ environment might help us!

Cheers.

[Bcousins]

Thanks for you reply

Basically I am assuming linearity between -10 and 0, &,  0 and 10 degrees (for the limits, upper and lower).

I would like to test the limit throughout the entire angle range aswell ( at the moment I just test at the given angles)

The process is testing a spring stiffness with angle. Basically I control pneumatics to rotate a shaft with an angle encoder & torque transducer attached. I get values throughout the entire angle range of the cycle and ,at the moment, am only testing at given angles I know the limits of, which the torque should be within.

I hope that better explains my problem, thnks again

[unclebump]

What type of data are you using, waveforms or arrays?? Can you post a picture of your graph??

[Bcousins]

I'm saving the data as an array in a text file

Mabe this pic will help

Its basically what i want to do - if the data exceeds the limits anywhere - fail

[unclebump]

Check the llb file I put at the end of this thread.

http://forums.ni.com/ni/board/message?board.id=170&message.id=191417&query.id=109498#M191417

[Bcousins]

Thanks for the reply

I saw this example yesterday but it seems to only give time on the x-axis and not the values that the good/bad graph shows,

I think I may run into problems with the negative x values ?

[unclebump]

Post some sample data and I'll see what it does.

[tbd]

Hi Bcousins,

      The attached VI is pretty simple, Angle-IN, limits-OUT.  The diagram is shown below.

Maybe you can use it with unclebump's code!

Cheers.

Message Edited by tbd on 01-11-2007 11:53 PM

[Bcousins]

Thanks guys

Unfortunately I do not have any test data on me today - i will have to make up some mock up data

but thanks again for the help