Re: Six-Arm Simpson

It's not fully constrained if you have an equilateral hexagon. It is fully constrained if you have a non-equilateral hexagon. In that respect, it has a lot in common with the Stewart Platform. In fact, you could use the Stewart Platform as a model for a Six-arm Simpson

There are two ways to constrain it: either make the base non-equilateral, or make the hub non-equilateral, or, even better, both. The closer you get to triangular on either the base or the hub, the more rigid the hub's position becomes. You can see that in the video I linked, they made both the hub and the base non-equilateral. That is, the arms are in pairs on the base, but they are in opposite pairs on the hub.