Create a custom muscle model with subcomponents

[Giuseppe Scaccuto]

Hi all,
I'm trying to compile a custom muscle model class with OpenSim 4.0 API but it seems it doesn't add two subcomponents related to the main class.

I used this: https://simtk.org/projects/afferents

This muscle extends Millard2012EquilibriumMuscle class and it adds two subcomponents which extend ModelComponent class.

My questions are:
1. For subcomponents class, I have to override ModelComponent methods calling Super::method() within them or it's useless?
2. For main component class, I can execute adoptSubComponent() method in the constructor for each subcomponent or I should use a different approach?

With these choices, It seems I can't load this muscle model in MATLAB as a plugin. It returns this error:

Code: Select all

Java exception occurred:
java.io.IOException: Model::equilibrateMuscles() Component has no underlying System.
You must call initSystem() on the top-level Component (i.e. Model) first.
	In Object '<no-name>' of type Mileusnic06Spindle.
	Thrown at component.cpp:798 in getStateVariableValue().

	at org.opensim.modeling.opensimActuatorsAnalysesToolsJNI.ForwardTool_run(Native Method)

	at org.opensim.modeling.ForwardTool.run(ForwardTool.java:117)

Thanks for your support.

[Thomas Uchida]

There may be some helpful information in the API Guide (in the doxygen documentation here: https://simtk.org/api_docs/opensim/api_ ... Guide.html). See, in particular, the "Writing your own Component" section (https://simtk.org/api_docs/opensim/api_ ... components).

[Giuseppe Scaccuto]

I read it but I don't understand how test my component with program in testComponents.cpp

How can I use this tool?

[Thomas Uchida]

I don't understand how test my component

If you are creating a new muscle and compiling from source, you could add test cases to testMuscles.cpp (https://github.com/opensim-org/opensim- ... uscles.cpp), as has been done for the other muscles.

[Giuseppe Scaccuto]

I have a problem with connection between model components.

I read API Guide on "Writing your own component" and it seems it need a socket to establish this connection. So I created a socket for both subcomponents and I connect it to the main component and when I compile and load the model plugin in OpenSim GUI it works but when I open the .osim model file, I got this error:

error.png (10.23 KiB) Viewed 686 times

I can't understand if there's something wrong with it, so I report XML code related to the .osim file too.

error2.png (45.72 KiB) Viewed 686 times

[Thomas Uchida]

The "Hopper Device" example on GitHub demonstrates some of the new features of the 4.0 API and might be helpful: https://github.com/opensim-org/opensim- ... pperDevice

[Giuseppe Scaccuto]

Well, when I load the hopper .osim model in OpenSim GUI, It returns same error while it works correctly on MATLAB.

Also my .osim model seems to work on MATLAB.

It should be a problem with OpenSim?

[Thomas Uchida]

It is very surprising for a model to work in MATLAB but not in the GUI. Are the MATLAB and GUI versions you are using derived from the same 4.0 beta? Did you use an installer or build from source?

[Giuseppe Scaccuto]

I used the Installer (4.0 Beta) for OpenSim GUI but I configured MATLAB with OpenSim Libraries builded from source core SDK (4.0 Beta).

[Giuseppe Scaccuto]

UPDATE: Ok, It works now!

The problem was in the socket tag on xml code in the .osim model file.

As reported in: viewtopicPhpbb.php?f=91&t=9636&p=26386&start=0&view=

Every tag should be contain the suffix "_connectee_name".