simtk.org

Where I can find documentation about algorithm used for optimization ? (ipopt or cfsqp)

Were Is possible to find osimFSQP library ?

Thank you for your help.
Andrea

I find a ref. for FSQP
Lawrence, C.T., Jzhou,J.L., Tits, A.L., 1997. User's Guide for CFSQP Version 2.5: A C Code for Solving (Large Scale) Costrained Nonlinear (minimax) Optimization Problems, Generating Iterates Satisfyng All Inequality Constraints. Techinal Report TR-94-16r1. University of Maryland, College Park

Andrea

This algorithm is actually available to the public for non-commercial uses as well; I'm not sure where to grab it, though, as the site I got it from before seems to not be around anymore.

-Dan

Thank you Dan.
I would like to understand the difference in algorithm.

Andrea

Hi Andrea,

There is an entry on the wiki about the optimizers that OpenSim uses here: http://wiki.simtk.org/opensim/Optimizers

On of the developers (Eran Guendelman) wrote a summary and comparison of the optimizers (optimizer_roundup.txt) that can be found in that wiki entry.

One of the big differences is that IPOPT is totally free and distributable, and that is what is packaged with OpenSim. CFSQP is not. CFSQP is distributed by AEM Design (http://www.aemdesign.com), which gives free licenses to Academic Institutions, but each institution must submit their own request to AEM. Thus we cannot distribute it with OpenSim.

In my experience with OpenSim, CFSQP is faster and seems to be a bit more robust than IPOPT. However, IPOPT has worked for about 95% of my simulations.

Thank you Samuel.

Andrea

how do you change from one optimizer to another?, in the static optimization im getting errors like
StaticOptimization.record: WARN- The optimizer could not find a solution at time = 0.996
Starting at a slightly different initial time may help.
Try increasing the strength of the following actuator(s):

and give no information about the actuator and this happend at every frame....

Anyone knows why this..

Thanks...
Pablo..

Hi Pablo,

please check the answer that Samuel posted in a previous thread!
https://simtk.org/forum/message.php?msg_id=1333

cheers,
Dimitris

I have aquired the source to the FSQP optimizer library in C and would like to know how to compile and include the dll file in OpenSim. Are there instructions available for doing this?

Cheers,

Tim

Hi Tim,

The folder that builds the cfsqp dll is a part of the OpenSim repository (under Trunk/Vendors/CFSQP). We could not make it public for licensing reasons. I can package it separately if there's enough interest..

Best,
Ayman