Joints

For a joint this becomes a set of equations for the linked degrees of freedom of the form. In the simplest form if the constraint axis of the two nodes are the same

$$u_{s} = u_{p}$$

When the constraint axes of the two nodes differ there is an adjustment of the form

$$u_{s} = D_{s}{D_{p}}^{T}u_{p}$$

Where $D_{s},D_{p}$ are the direction cosines associated with the secondary and primary nodes respectively