MATLAB accessibility of SimBody methods in OpenSim 4.0

[Hide Kimpara]

Hello,

We used several methods of SimBody APIs to control our OpenSim model.

The functions we used in C++ programming were like followings:

• _model->getMultibodySystem().realize
  _model->getMatterSubsystem().calcResidualForceIgnoringConstraints
  _model->getMatterSubsystem().multiplyBySystemJacobianTranspose
  _model->getMatterSubsystem().calcM
  _model->getForceSet
  
  MobilizedBody& findFrameTransforminGround
  MobilizedBody& findFrameVelocityInGround
  _model->getMatterSubsystem().calcStationJacobian
  _model->getMatterSubsystem().calcFrameJacobian
  _model->getMatterSubsystem().multiplyByMInv
  _model->getMatterSubsystem().calcBiasForStationJacobian
  _model->getMatterSubsystem().calcBiasForFrameJacobian

In case of OpenSim 4.0, can we use them directly from MATLAB? Or do we need to still think about keeping C++ programming between MATLAB and SimBody APIs?
Unfortunately, we have not succeeded in MEX programing until today.

Thank you
Hide

[Thomas Uchida]

You can call methodsview(Model) in MATLAB to see which methods have been "wrapped" (are accessible through MATLAB) for the Model class. In case you need it, the doxygen documentation for the latest build of 4.0 can be found here: http://myosin.sourceforge.net/1978/.

[Christopher Dembia]

Many of these methods should be available. See here for an example: https://github.com/opensim-org/opensim- ... tSimbody.m

[Hide Kimpara]

Hi Tom,

Thank you for your quick response.
I changed path files of MATLAB. Then there is no error on "import org.opensim.modeling.*". However, if I try to read some models using Model('aaa.osim'), error happens with pop-up message saying "Required library failed to load. Check that the dynamic library osimJavaJNI is in your PATH java.lang.UnsatisfiedLinkError: C:\opensim-core\bin\osimJavaJNI.dll: The specified procedure could not be found".

Then another error message comes on Command Window:

Code: Select all

Java exception occurred:
java.lang.UnsatisfiedLinkError:
org.opensim.modeling.opensimSimulationJNI.new_Model__SWIG_1(Ljava/lang/String;)J

	at org.opensim.modeling.opensimSimulationJNI.new_Model__SWIG_1(Native Method)

	at org.opensim.modeling.Model.<init>(Model.java:783)

Do you have any solutions?

Thank you,
Hide

[Kenechukwu Mbanisi]

Hello Chris,

Many of these methods should be available. See here for an example: https://github.com/opensim-org/opensim- ... tSimbody.m

I'm absolutely delighted to see that we have access to Simbody methods now from MATLAB, great addition!

Is there some documentation for MATLAB API? It would be very helpful to have a way to 'look-up' corresponding methods and functions from Simbody.

Thanks again,

Kenechukwu

[Thomas Uchida]

Hide: Do you have any solutions?

I would need a lot more information to diagnose the issue. I suggest discussing the issue in your meeting tomorrow so you can work out the details in real time. Assuming the Windows PATH environment variable is correct and MATLAB has been properly configured, perhaps you built OpenSim 4.0 from source but didn't check the box in CMake to build bindings?

Kenechukwu: Is there some documentation for MATLAB API?

Although not all methods are available from MATLAB, you can still use the doxygen documentation as a reference. Here's the documentation for the most recent build of 4.0: http://myosin.sourceforge.net/1978/.

[Ayman Habib]

Hi,

The message "The specified procedure could not be found" suggests that the library in question was located indeed but it is missing some symbols that the Java bindings are refereing to. This likely is due to the JNI library being loaded not consistent with the java class files. Make sure you have only one installation of OpenSim on your machine, or if more than one make sure the one you want to use is at the front of the Path and is used by Matlab.

Hope this helps,
-Ayman

[Christopher Dembia]

It sounds like you've built from source. If you run the OpenSim tests (in Visual Studio, this is the RUN_TESTS or RUN_TESTS_PARALLEL project; from the command-line, you can use ctest; see the README for more information), you should see some MATLAB tests are run. Do those pass? If so, that tells you that you *can* get the environment working properly, but that there are just some configuration issues (PATH, etc.).

[Hide Kimpara]

Dear Tom, Ayman, and Christopher,

Now I solved!

Code: Select all

org.opensim.modeling.opensimCommon.GetVersion()
 
ans =
 
4.0

I believe the main reason would be PATH for MATLAB. I installed R2016a and R2016b. Since I mostly used R2016a, I deleted PATH for R2016b. But I found OpenSim 4.0 recognized R2016b as the MATLAB during the intall.
So, I add PATH for R2016b, then it works!

Thank you so much for the kind supports!
Now we concentrate on accessibility from MATLAB to methods of force and position feedback controls.


Thank you,
Hide

[Christopher Dembia]