We are working on a modified version of the human seated model and would like to understand better the force distribution between conditional contact points.
As shown in the below image, we have multiple conditional contact points defined along the spine. The contact is defined with the coordinate frame shown in yellow color. When we run the inverse dynamics analysis, nodes at backrest support gets reaction force levels as shown below. We were expecting a more uniform distribution along these points, and it is particularly interesting that the closest support points not getting any reaction force. We speculate that this is related to the global muscle recruitment algorithm deciding on the reaction for distribution. Can you please comment on this?
I think you answered your own question - the muscle recruitment finds an optimal in terms of equilibrium solution, where the most capable to contribute pushing muscle is employed. You could “distribute” the loads more uniformly by decreasing the strength of these muscles so they would be more penalized on activation. Also the number of contact elements is not very large because a low number of them could ensure force/moment balance due to larger strength.
As for the distance, you could decrease the sensitivity of each contact element to have them activating closer to the back rest surface.
Thank you for your super fast reply. I think this was half a confirmation question. Your suggestion on contact distance and strength adjustment is very much appreciated.
