Dynamic Simulation Parameters

[JOSEPHKOVACH7324]

I have a few questions related to dynamic simulation...

1) When using the "formula" rule in the input grapher, can I access "parameters"?  It does not appear to work.  Where "parameters" I am referring to variables found in the "f(x)" menu. 

2) Where is the documentation describing the syntax of the "formula" rule in the input grapher?  I stumbled upon something like (P[1] Spatial:2) purely by a lucky google search.  Clearly white space matters.  Is this documented somewhere?

3) Can the "parameters" menu access variables from the dynamic simulation environment? 

    I notice it auto-populates with a few:

       Final time / Simulation Player

       Number of images / Simulation Player

       Friction / 3D Contact:1

       Etc

But it does not appear that I could access something like (V[1] Spatial:2) for instance.

Even adding that as a user parameter, it cannot parse the name.  This would be useful for giving more human readable names to these values.

4) I am trying to implement a crude PID loop in a simulation to control a force.  I can do the "P" using the "formula" rule in the input grapher, but it is a bit cludgy since the dynamic simulator environment does not seem to be aware of the parameters menu.  Therefor I cannot give easy names like "Pgain" and have to use magic numbers directly in the formula.  Although it does work.

How would I implement Integral?  I would need to define an error variable, and be able to increment it by SetPoint - (P[3] (Spatial:2)) each frame of the simulation.  Is this beyond the scope of Dynamic Simulator?  Can I do this with the API, if I had the time to learn it?

[JDMather]

Are you using the Wasim Youins book to learn DS?

Can you post sample assembly here?

[JOSEPHKOVACH7324]

No I am not using a book.

My questions are not specific to a given assembly.  I have attached the test assembly I was working with.

[JDMather]

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@JOSEPHKOVACH7324 wrote:

But it does not appear that I could access something like (V[1] Spatial:2) for instance.

4) I am trying to implement a crude PID loop in a simulation to control a force. 

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I hope you stick around here for a while, I've been searching for several years for someone to colaborate with on stuff like this (there doesn't seem to half a dozen users of DS in the world).  I like to keep stuff like this in an open forum, but first I would like to run some private stuff by you - please contact me jmather_at_pct_dot_edu (and as an aside for anyone reading this thread - we do have an open faculty position).

I have not tried to do something exactly what you are attempting but V[1] (Spatial:2) is an output resultant of running the simulation.  If you go to the Output Grapher you can track this value with a new (user created) curve variable (I named New_Curve, but it could be any desired variable name).

And get the Wasim Younis book (Part 2) Amazon.com - there are a lot of mistakes in the book, but I use them as teaching points.  A lot of useful stuff as well.

[QuasiMojo]

Thank you for your post. I'd been interested in the Dynamic Simulation tool but hadn't any time to get acquainted until now.  I was playing around with your forces and ran into the same problems you had with using parameters. I was able to define two parameters {x1,x2} = {0,180}deg and apply them to the startin and end points of your ForceZ; however, once entered they became un-related constants.  When I changed the value of x2=100deg, there was no change in the ForceZ ending point value.  I also could not enter any parameters into the overly-hopeful "Formula" property.  I was very suprised and disappointed by this lack of parameterization, since that is the core of the whole program in my opinion.  I hope Autodesk (or the forum members) can elaborate on this and improve the documentation. It might help the adoption of the tool to reach a full dozen users

-Andrew