How to compute general mass matrix in c++?

[Dídac Coll]

Hello,

Right know, I am working with a double pendulum and I am trying to control each joint of it with the following control law:

controlLaw.png (3.16 KiB) Viewed 729 times

where U(\theta,t) is my control law ( The angular accelerations are computed there taking into account the error generated by the position of the joint). My question is:
How can I obtain the M(\theta) with the OpenSim API. I think there is a method called SimTK::SimbodyMatterSubsystem::calcM() but not sure if what I am looking for.

Thanks!

[Dimitar Stanev]

Almost every calculation related to the EOM is accessed in:

https://simtk.org/api_docs/simbody/3.5/ ... ystem.html

I suggest you read the Dox carefully in order to understand Simbody's convention. Yes can use

Code: Select all

calcM()

, but first you need to realize the model to position stage because M(q) is a function of the positions (q).

Best

[Dídac Coll]

Thanks for the answer Dimitar.

Best regards

[Sarah Roelker]

Is it possible to use an analogous call to compute the mass matrix in Matlab?

[Dimitar Stanev]

Yes, but you must use the latest version of OpenSim (v4.0).

[Sarah Roelker]

Okay thank you!