Thank you for the answer. For the interested reader: in the suggested paper an adjusted model was made for each trial separately. Then a final model was made by averaging the mass properties of the bodies of the different models.

Any other suggestions?

Hi, I have experimentally measured kinematics and ground reaction forces of several gait trials of the same subject. I would like to use the RRA tool to adjust the mass(center) of the different bodies in order to get the residuals on the pelvis as small as possible. However, it does not make sense t...

It seems to be fixed now.

Hi, I have a problem with the search function of this forum. If I type a word and hit the search button, I get the error message: "You must specify at least one word to search for. Each word must consist of at least 3 characters and must not contain more than 14 characters excluding wildcards." I tr...

If I'm correct you know
[*] The positions, velocities and accelerations of every body
[*] All external forces, except the external force from the chair.

In this case, you can find the unknown external force by the law of conservation of momentum.

Ok, I reported the issue.

Hi, I think the current inverse dynamics solver is suboptimal and can be faster. In the current code, the stage is realized to dynamics. This is however not necessary, the velocity stage should suffice, since this stage already allows to compute the coriolis forces. I added some code, where I compar...

Thank you very much. Everything works now!

Just out of interest, why does osimModel.getBodySet().get(i).getInertia(rInertia) does not return the same result as osimModel.getMatterSubsystem().getMobilizedBody(i).getBodyMassProperties(s).calcInertia() ?

Thanks for your answer. Since I want to compute h for the total system I think I still need to multiply with the jacobian of each body: mbs->realize(s, SimTK::Stage::Dynamics); for (SimTK::MobilizedBodyIndex i(1); i < sms.getNumBodies(); ++i) { colForce = osimModel.getMatterSubsystem().getTotalCentr...

Hi, The dynamic equation of a total system can be written as: M(q) * udot + h(q, u) + g(q) = tau + J^T*Fext with M the mass matrix, h the coriolis and gyroscopic forces, g the gravitational forces, tau the mobilizer forces, J the jacobian and Fext the external forces. I'm interested to know the valu...