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Hello

I am using this model by Hang Xu (https://simtk.org/frs/?group_id=933) and added 4 more muscles in the legs. When I run the IK results associated with grf they are not consistent. I decided to use RRA to counter this, however, I am getting this error..

java.lang.RuntimeException: SimTK Exception thrown at SmallMatrixMixed.h:879:
Error detected by Simbody method lapackInverse(Mat<>): Matrix is singular so can't be inverted (Lapack getrf info=5).
(Required condition 'info==0' was not met.)

at org.opensim.modeling.opensimActuatorsAnalysesToolsJNI.RRATool_run(Native Method)
at org.opensim.modeling.RRATool.run(RRATool.java:156)
at org.opensim.tracking.RRAToolModel$RRAToolWorker.construct(RRAToolModel.java:136)
at org.opensim.swingui.SwingWorker$2.run(SwingWorker.java:130)
[catch] at java.lang.Thread.run(Thread.java:748)

Can anyone help me with this?

Thank you

I decided to use RRA to counter this

Has the model been designed for computing dynamics? If not, perhaps check for body segments that have zero mass and/or inertia, which could cause the error you are seeing.

Thanks for responding Dr. Uchida.

tkuchida wrote: ↑

Fri Dec 09, 2022 10:55 am

Has the model been designed for computing dynamics? If not, perhaps check for body segments that have zero mass and/or inertia, which could cause the error you are seeing.

All the body segments have a mass /inertia so that's why i am not really sure what else could it be.

There may be some useful information in the discussion on Topic 4242: viewtopicPhpbb.php?f=91&t=4242