time of forward simulation

[Ricardo Lameira]

hello,


I created a trapdoor to study the ankle sprain. The trapdoor only allows inversion movements, maximum 30 degrees.
To improve the model it was incorporated a set of ankle ligaments. Subsequently, to ensure that the foot has the same movement to the trapdoor, a weldconstraint has been created between the foot and the trapdoor. But, when i simulate the movement with the ligaments inserted, the time it takes for the trapdoor to reach its maximum point is higher if I simulate without the ligaments. The ligaments retard the movement of the trapdoor.
How do I get the trapdoor to always have the same fall time (action of gravity)? Independently of the structures incorporated in the model.



Thank you

[jimmy d]

Ligaments provide passive forces that resist stretching. You could add a prescribed motion to the trapdoor coordinate. You can take the trapdoor coordinate motion from the simulation without ligaments and prescribe those coordinates to the trapdoor in the simulation with coordinates.

Just realize that if you do it this way, the trapdoor will be providing a force and effectively 'pulling' on the foot.

[Ricardo Lameira]

Hello,


therefore, is it not preferable to use the prescribed movement only of the trapdoor without any other body? For example the muscles that the model includes offer resistance to movement.
To solve the problem, I should use the "CoordinateCouplerConstraint"?


Thank you