Robot Arm Advice

Hi CG Cookie Team! 

I just sent this message to Wayne, but if anyone else has a comment on this, I'd love to hear some feedback. Here is the message I sent to Wayne. There is also a movie and .blend file I submitted, but I don't know how to link to those here or upload them again. 

Hi Wayne,

As I tried to explain earlier, I have a personal project that is a robot arm for a prior job I worked on. Originally I animated it in Maya using empties. (Amateur move, I know… but it's all I could do back then.) I exported an Alembic file out of Maya and I wanted to import the file into Blender to add lights, textures and animation. But I was having a lot of issues with object origins and parenting messing up copies of the robot arm that I moved around the scene.

After chatting with Jason at Orange Turbine, he convinced me to set up a rig for this. So that's why I'm taking your rigging course. I think I've watched most of the relevent lessons, and still trying to get through the Crane Rigging lesson. But I'm also trying to rig my robot arm as I learn basic concepts.

So far I've added the bones, but I've got a few tricky things to figure out on this. If you take a look at the movie file, it will all make sense. First, I don't know if I should create an IK or FK constraint on the bone chain. Also, which direction should the IK/FK constraint be heading - up or down?

In the middle of the vertical bone chain, there is a rubber hose that stretches downward. I assume that I should use a "Stretch To" constraint? And will this interrupt the IK or FK constraint since it's in the middle of the bone chain? At the bottom needle area those parts also have independent movement for extra "thrusting action", so they will probably need a "Stretch To" constraint as well.

At the top of the robot arm there are two pivot points. Do I need a control bone and/or widget up there somewhere? Or should I control everything from the bottom?

And finally, there are the claws which open and close. For now that set of bones is pulled away from the vertical bones, but there is still a relationship line connecting them as part of the same armature. They also need to stick with the descending claw structure geo.

Since most of this robot arm contraption are composed of separate parts, do I need deformer bones as well as Control Bones? Do I need a Root bone at the top or bottom?

Sorry for all my questions, but I'm just trying to get my head around all this stuff so it's practical for my personal project.

If you could maybe just do sketch indicating what you would recommend in terms of what goes where, I'd really appreciate it!

Thanks,

-Scott