It is used for rotation transmission between the shafts, relative position of which in space is arbitrary.
Unusual thing: two links are connected together via two joints (not one joint):
- Yellow part is connected to the input pink shaft via a spherical joint and a point-on-plane joint.
- Yellow part is connected to the output green shaft via a point-on-line joint and a point-on-plane joint.
The simulation shows that it is a constant velocity joint except the case when the input and outpot shafts are skew.
The video shows case when the shafts intersect with one another at angle of 15 deg.