CFSQP and IPOPT

[yuma ieshiro]

Hi All,

I am going to understand OpenSim from a viewpoint of the C language.

In CMC or RRA, I studied that OpenSim used the CFSQP or the IPOPT. In the C language, how is the change of those optimization problems in OpenSim when a dynamics simulation? Although the source code was downloaded and the code was investigated, I was not able to understand it.

Can you please tell me?

Best regards,
Yuma

[Stephen Riutta]

Hi Yuma,

IPOPT is OpenSim's built-in optimizer. CFSQP is a different optimizer that must be obtained separately from another source. Past links to it seem to have expired, so I don't know where it can be obtained from.

Hope that helps,

Stephen

[Ayman Habib]

Hi Yuma,

OpenSim formulates an optimization problem to solve the redundancy of muscles and actuators at each time frame (possibly re-using model state to maintain continuity). The two optimizers you mentioned can be used to solve the same problem. IP-OPT is open source and is included with OpenSim/simbody as Stephen mentioned, while CFSQP is a third party package that has its own license but can be used if installed.
The following page describes the various optimizers available and the differences between them.
http://simtk-confluence.stanford.edu:80 ... Optimizers

Hope this helps,
-Ayman

[yuma ieshiro]

Dear Mr.Stephen and Mr.Ayman,

Thank you for the quick reply.
When I was going to use CFSQP by OpenSim, I learned that osimCFSQP.dll was required. And in order to have got osimCFSQP.dll, I also learned that I had to apply to the maker of CFSQP. I intend to contact to the maker.

Is my trouble solvable by doing so?

Best regards,
Yuma

[Ayman Habib]

Hi Yuma,

Yes, and please let us know how it goes.

Best regards,
-Ayman