Some pointers appreciated--Mechanical Rig(3ds max+any)

[Lande3D]

Hello fellow cgtalkers. Im trying to rig this thing i made in 3dsmax:

its the fuel flex valve from a rocket engine. I have hidden the top and bottom metal flex tubes to make the problem parts(the 6 hinges) easier to see.

The valve is a part of a larger rig with another flex valve on the other side and a gimbal hinge in the center. This is why the valve looks like its rotating a bit off center in the animation clip, since the bottom “platform” of the valve rig is childed to the main gimbal rig.

edit:

More visual explanation of the current rig
Edit 2:

More notes.
As you can see in the clip the rig is currently sortof working, except for that the hinges are rotating out of their mounts.
Im using separate ik chains for each of the hinges and the center “platform” is rigged with a rotation+position constraint to both the top and bottom “platforms”.
The issue currently is that from what i can gather from the reference the only part of the hinges that can rotate is the center joint(which iwe modeled to allow for a ball joint rotation up to 20 degrees). but the base of the hinges are currently rotating out of their mounts.

My thinking i have to somehow make the center “platform” rotate correctly to face the both the bottom and lower hinge centers by rotating off axis. or maybe i can IK rig the entire thing?problem is that i still havent been able to get very predictible results by using the ik limits.

Is it true that this mechanism is similar to a stewart platform? I know its actively articulated and this is passive but its the only thing iwe found that has a similar looking joint.

Any ideas?

Btw if anyone knows anything but its related to maya/blender/modo etc. I do have experience in those 3 plus others so it would still be very helpful.

[mister3d]

I\m not a specialist, but aren’t IK chains are limited by its nature to be locked in one plane of movement? I’m not quite sure how the setup of those hinge arms was made from the description.
Maybe it would be easier to go with a 3-pivot setup? LIke the hinges are a bone, and the center of the triangle is its angle ofrotation?

[mister3d]

I tried to replicate it, and I reckon it might defy the laws of physics. If you try to rotate two adjacent triangles, they can’t hold their initial shape.
As I understand, you rigged those green arms to the bone directly, and the bone is changing its angle, not related to violet hinge mounts.
If you still need to use the same animation, you first need to fix those hinges. For it, create bones or helpers where they are located separately for each side, with bones going from a hinge to the middle of your IK chain. You can create stretchy bones and skin to them green arms. It will get some stretching, but it won’t go out of place in hinges area.
Stewart platform is a correct solution, so that the triangle of the arms won’t stretch, but have telescopic arms.
3 pivots.max (240 KB)
triangle.max (288 KB)

Here are some videos on rigging hydraulic parts https://www.youtube.com/results?search_query=Digital+Tutors+-+Modeling+and+Rigging+a+Hydraulic+Crane+in+3ds+Max

[Lande3D]

Thank you so much. Ill take a look at your scenes and respond later. Have to get the complete picture, and im at kfc now using their wifi… Btw i didnt even know you could do strechy bones in max, tells you about how much i know about rigging:-P

Damn. This thing looked simple enough but its really been a headache to rig. Iwe rigged some kindof complex mechanical chains before but this has to be the most difficult to wrap my head around.
Iwe been doing some research on the subject since i posted the original post and i found that this type of mechanism is called a Universal metal expansion joint.

The references to one im trying to replicate is here:

can anyone see something i cant? The real one does pivot with the main assembly(ill try to locate a video of it in action).

ill try to take a look at the yt video but im in china travelling right now and everything is blocked. damn i miss google.

Edit: stripped the scene of the valve and saved it out in a file if anyone wants to try out something on it.
FlexValveExport.max (8.5 MB)
this scene doesnt have any rigging whatsoever. The entire hirearchy is just childed to the top platform and it has a few circles at each of the platform centers. All the objects has centered pivots and are rotated locally(but all their scaling is 1,1,1) so stuff can easily be aligned to them. (Obs i just noticed i forgot to reset the mateditor so there are a few vray+plugin mats/tex stuff in there that may give a missing plugin warning. but nothing is applied to the scene so it should probably still open fine)

[Lande3D]

I finally got a chance to have a look at this again over the weekend.
Thanks to the pointers from here as well as a bunch of work on my own position scripts i finally have it. i present to you what is very likely the only working canfield joint rig made outside of a cad software. It works as an IK rig but its all position scripts as well as some look at constraints position constraints and parenting controlling the motion.
its not perfect(doesnt have limits so it just pulls apart when the range of motion is exceeded)

Old thread i know. but just wanted to give a huge thank you to @mister3d for helping me get started on this.
I now have to find a solution to getting the second joint going on top working together with this one to make it a complete rig.