November 15, 2012
Planar Loops in 3D Mechanics II
The problem is the following: There are two planar closed kinematic loops each defined by three revolute joints and a prismatic joint.
Two revolute joints with the same rotation axis suffice to restrict the freedom of motion to a single axis. The constraint of the third revolute joint is therefore superfluous, which leads to an additional redundancy that doesn’t get removed by the automated loop-breaker algorithm.
For this reason, a special revolute cut joint was introduced in the 3D mechanics library that can be used to break planar closed kinematic loops in 3D mechanics.