Error for Inverse Dynamic Analysis

I set new rotating and linear drivers on pelvis to substitute the original pelvis drivers in the example of “FreePosture”, however, when operating the inverse dynamic analysis, the error came as following:
ERROR(OBJ.MCH.MUS4) : …:Study.InverseDynamics : Muscle recruitment solver : solver aborted due to singular KKT matrix.
So I am quite wondering how to solve the above problem~

Hi Elizabeth

This error appears when the muscle can not balance the model.

The error would typically be that there are missing boundary conditions to the world, so if you pelvis driver do not have any rections on to the world and there is nothing else being able to hold the model you would get this error.

Please see these trouble shooting pages on the wiki on the subject
http://wiki.anyscript.org/index.php/Model_trouble_shooting#Make_the_solution_of_the_inverse_problem_stable.3F

Also if you are running the model with no oridnary muscles on it may cause a problem. In this case the model has moment generating muscles applied in the joint instead but they can only deliver a moment in a limited range so this could also explain this, try swicth on the muscles in the BodyPartSetup.any file.

Best regards
Søren