Cineversity

Hi,

I’m trying to rig a mechanical arm with parts either rotating forward or twisting but not both.
The preferable set-up would be an IK.

The problem is IK rotates all object’s axis to arrive at a point, which gives an unexpected behavior.

You can see an illustration video here:
https://www.dropbox.com/s/6xk4nek2j1ai7m4/c4d139_limit_rotation_in_ik.mp4?dl=0

You can check the illustration file here:
https://www.dropbox.com/s/k53sp3lstneoyy6/c4d139_limit_rotation_in_ik.zip?dl=0

Of course, I wouldn’t expect the IK-setup to have the perfect solution but I was hoping I could get close by just limiting the rotation axis of objects affected by the IK.

Is there a way around this?

Hi Ben,

I took so far the whole morning to explore if I’m not too pessimistic with my opinion that I gained over the years about it. Here is my conclusion:

Your questions would lead to think about a proper Pole set up and limit the Joints>Kinetics to get a mechanical rig. I have not seen a set up with so many axis freedom/constrain and a single IK, with no extra rigging, that worked.

https://help.maxon.net/us/#TCAIK-ID_TAGPROPERTIES

I can see that this comes close to explain the underlying problem
https://www.cineversity.com/vidplaytut/creating_a_no-flip_knee_rig

Brainstorming: If the core knee could be defined, the positions of that joint set up could be used. All parts need then to get their orientation from Target setups. Again, I feel even suggesting it uncomfortable. If I interpret your set up wish correctly, I count seven cases where the joints need freedom, which needs to be solved, besides eleven that need to be constrained to zero movements. The numbers might vary by a few, dependent on the target.
As a side note, the Goal might not work alone, more input might be needed

I’m currently not convinced that the time spent to build a rig with all needed parts around it, will give you in all cases a stable result, as well as, that the invested time is not larger than to animated it manually.

However, it is undoubtedly a great exploration to see where the limits are, and perhaps you develop something useful anyway. Enjoy the time developing it.

This would be the maximal control that a single Goal can direct. Anything else needs more input when the lower or/and upper arm follows (or not). That differentiation will make the set up more complex and closer to the manual set up.
https://www.amazon.com/clouddrive/share/0NXPnxjTIzJA6SiJdkbKMpvSyLUcVEVvlgRbtKNDYo8

My best wishes.

Thanks for the response and some insights

Sorry if I misled you but back to the main question:
Is there a way to Limit Rotation of an Object with IK Tag?

I should have said above that I also tried protection tag but it didn’t work.

Is there away around this?

You’re very welcome, Ben, thanks for the reply.

As I mentioned, please explore the options of the
Joints>Attribute Manager> Kinematics (all).

Enjoy

Thanks for clarification specially on adding the phrase “Attribute Manager”. I initially thought it was a menu, that’s why I couldn’t find it.

Have a great day ahead!

Have a great day as well, Ben.

Perhaps find first a concept of how you would like to direct the robot arm, then find out how to use that information. I think this kind of robot arm needs at least two IK setups.

Note that the first joint element in an IK set up can’t be limited with Kinematics, the Restriction-Tag needs to be used, but be aware of the Euler Problem.

Cheers