Android 12 Knee assembly.
This page is about Android 12’s knee assembly, check out the project index for the rest.
As with the foot, all of the parts will be 3D printed, so my initial work is to design the pieces in CAD. I’m using Autodesk 123D, which is free software. There’s a YouTube video for this section, or scroll down for pictures and words.
Here are the initial pictures of the lower knee joint assembly.
And the upper part of the knee hinge with its servo mount:
The knee hinge is offset towards the back, behind the studding that makes up the vertical parts of the leg. This means that as pressure is applied downwards the knee stays locked, much like a human, but as the leg lifts forward the servo can slacken the tendon/spring to allow the knee to bend. As with the ankle, the knee will use a gyro to make the servo/spring tension as dynamic as possible based on the motion of the leg.
Video about these parts at the top of the page.