Hi Christopher, My ultimate goal is to study a passive arm exoskeleton, the problem I have is that when trying to analyze the moments of the joints I get unexpected results because Opensim seems to bypass the constraints when performing the inverse dynamics. To better understand how Opensim works, I...

Hello Nicholas, first of all thank you for your reply. The mechanism has 1 degree of freedom, that allows me to enter the movement using a single link and the others move accordingly. As input I use an angular velocity of 1 rad / s constant, which means that the angular acceleration must be 0, but M...

Hello, I want to carry out the kinematic and inverse dynamic study of a four-bar mechanism. The mechanism is made up of 3 movable bars and 1 fixed, and I use 3 joints and 1 point on line constraint. The mechanism has a degree of freedom and when performing the kinematic study at constant speed for t...

Thanks Dimitar, Could it also be solved using MOCO?

exo.png Hi, I am trying to join the following exoskeleton to the arm, to achieve this I have used a weldconstraint to close the system. The problem is that when doing the inverse dynamic study, the weldconstraint is omitted, obtaining unexpected results. Is there a way to get the resolution to work...

Sin titulo.png Good afternoon, I have created a four link bar mechanism to do a series of tests, my problem is, the mechanism cannot move and I don't understand why. The axes of rotation are all parallel. As it is a closed system to connect the red link with the blue one I have created two equal mo...

Good morning, thanks for your reply Ratna.
The mass of the two plates is 0 Kg, I did so precisely so that it did not affect. So I see so strange difference

Good afternoon, I have tried to connect a spring directly to humerus and ulna, and on the other hand I have connected the same spring to two plates attached to the arm. When comparing the elbow flexion moment, I do not understand why there is such a difference between the two cases. Does anyone know...

Hi, thanks for your response. As forces excluded are only the muscles, so the spring must act. It occurs to me that to connect the exoskeleton to the arm I have used a ConstraintSet. Can it not transmit the force generated by the spring to the arm because of that? Thank you <WeldConstraint name="wel...

I don't understand your reasoning. The kinematic study is always the same, but the dynamic study should change when modifying the spring stiffness, since the external forces applied to the model vary. It is not possible that the moment supported by the elbow is always the same when I modify the cond...