Constraints
FreeDyn provides generic constraints, a translational and a rotational constraint (abbreviated here by TF and RF), which allow the user to assemble all possible kinds of constraints between two bodies or between one body and the ground.
As a special feature, FreeDyn provides beside the generic constraints also a Spherical Joint and a Fix Joint as additional constraints (abbreviated here by SJ and FJ), which – of course – can be realized as well by using the generic joints, but regarding computational time, e.g. a Fix Joint should be realized by its representative and not by using six generic joints.
The user inputs can be position vector or direction vectors which have to be defined in the global coordinate system.
| Name | # of free DOFs | # of constrained DOFs | used constraint |
|---|---|---|---|
| Fix Joint | 0 | 6 | FJ |
| Fix Joint | 0 | 6 | RF, RF, RF, TF, TF, TF |
| Spherical | 3 | 3 | SJ |
| Spherical | 3 | 3 | TF, TF, TF |
| Revolute | 1 | 5 | SJ, RF, RF |
| Sliding Joint | 1 | 5 | RF, RF, RF, TF, TF |
Motion
FreeDyn provides a time-motion as a constraint equations, which depends on a measure and a time-spline. The difference between the measure and the time-spline must be zero during the simulation. Thus, a body can be moved along a prescribed path.