Hi, I am trying to model a lifting activity and my subject is obese with a BMI close to 40. In inverse dynamic study I face the error "Muscle recruitment solver : solver aborted due to singular KKT matrix" I have reduced the criteria power to 2 and increased the muscle strength and I still have this issue. I have simulated the same activity for normal subjects and it was OK.
the KKT error is probably because you are missing a constraint in the model and not because it is to weak.
Try to figure out if any of your segments are missing a constraint.