Rigid Link

A rigid link imposes the same velocity on all secondary nodes in one or more directions. The directions are defined to a skew or global frame. Figure 1 displays a rigid link.

Figure 1. Rigid Link Model

The velocity of the group of nodes rigidly linked together is computed using momentum conservation (Section Definition, Equation 1). However, no global moment equilibrium is respected.(1)

$$V^i=\frac{{\displaystyle \sum _{i=i}^N{m}_i{v}_i}}{{\displaystyle \sum _{i=i}^N{m}_i}}$$

Angular velocity for the i^th DOF with respect to the global or a skew reference frame is:(2)

$${\omega }^i=\frac{\left({\displaystyle \sum _{j=1}^n{I}_j^i{\omega }_j^i}\right)}{\left({\displaystyle \sum _{j=1}^N{I}_j^i}\right)}$$