Sigmoid Function for a waveform chart that plots calculated dat

[AJcpt]

I want to add a sigmoid function to my waveform chart. Right now when I increase the throttle the chart shows that the amplitude changes to the new value straight away without  a delay. So I want to implement a sigmoid function that takes me from the initial value to the final value with a smooth S curve implemented. Is there any way to do this?

[GerdW]

Hi AJ,

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@AJcpt wrote:

So I want to implement a sigmoid function that takes me from the initial value to the final value with a smooth S curve implemented. Is there any way to do this?

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Yes, sure!

Write down the math on a sheet of paper, then implement the formula in LabVIEW!

[AJcpt]

The issue is lets say I use y=1/(1+e^x) the x is a time value that is a part of the waveform chart rather than be in input so I am finding it difficult to implement this? I hope that makes sense

Any solutions to this?

[GerdW]

Hi AJ,

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@AJcpt wrote:

The issue is lets say I use y=1/(1+e^x) the x is a time value that is a part of the waveform chart rather than be in input so I am finding it difficult to implement this?

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"Time" is not a "part" of the chart...

As you run the code inside a loop: how much time does the loop need for one iteration?

"x" will be the same as "ierations * time_per_iteration"!

Or you simply determine the time difference between start of loop and current time...

[AJcpt]

All I need is one iteration per loop

[AJcpt]

do you have an example on how to do this please?

[altenbach · Accepted solution]

Maybe all you need is an exponential filter.

The entire "filter" can easily be wrapped into a subVI. An example for multiple channels can be found here, but you could easy create a VIM that accepts scalars and arrays.

 

[altenbach]

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@altenbach wrote:

... but you could easy create a VIM that accepts scalars and arrays.

 

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Here's how that could look like: