An anatomically correct 4-bar knee joint was designed for a knee brace used in action sports. The intent was to mimic the natural movement of the knee, unlike the hinge designs currently on the market. This design exercise was completed in 1 week as part of an interview process. Patent protection was eventually filed.
Reference points were added to several frames of a knee animation.
Mapped reference points were motion-mapped to determine 4-bar linkage points.
A 2D hinge mechanism was then modeled over the hinge points determined earlier.
A 2D 4 bar linkage was motion mapped and overplayed onto the medical animation.
After verification of the 2D overlay, a 3D hinge was modeled and animated here. Note the hard stops incorporated into the housing so hinge members cannot hyperextend.
Leaf Springs: Similar to the elastomer above but with more abrupt rebound at the the limits. The "attach position" has a wider movement range without any resistance from the hinge itself. Adjustment of both range and resistance is also possible.
Torsion: A single pivot point is equipped with a torsion spring. In one direction, the spring opens and wants to recoil. In the other direction, the spring closes and wants to open. This is a less elegant and less flexible (excuse the pun) option and was created for a more exhaustive patent disclosure.
