Hello. I’ve been creating a robot rig for a series idea I want to make. So, I finished the endoskeleton, and even partially rigged it, and started on a face with its own rig.
Now, I’ve come across a few difficulties. First of all, when I started modeling the robot, I made this pelvis.
I have no idea how to rig that! It’s pretty intricate, but my brain tells me that it isn’t impossible. Secondly, I came up (well, not really… If you were into LEGO you may recognize these) with these feet…
This problem is getting the pistons to expand and contract correctly. My current setup for the feet does this…
And for the third problem, and probably the most complicated…
This is head I was working on for the character.
Those lines around the head (that aren’t the grid) are bendy bones that I was setting up. Now, I’ve attempted to rig this already, and it is frustrating! I have no idea how to rig faces properly using shapekeys, let alone b-bones! … In fact, this is only my second proper face, and the only one I’ve really “finished.” But I know it’s possible from this video. (I don’t need to add the sculpting shapekeys for this character, but that’s so cool!)
So, does anyone have any ideas as to how to rig all of these things? My experience with rigging is really only hard-surface rigging, which is basically parenting or weight painting individual pieces together, low-poly rigging, and lattices.
Here’s the blender file. They’re technically two files, so I put them in one for your convenience. The head and endoskeleton are in separate scenes. The password is BlenderArtistsOnly.
Thank you! 
I recently updated the piston rig, and it works a lot better now, but there’s still a few issues with it. I’ll upload an updated version of that Blender file.