XM Magdalena 3D print, GGeorgy (3D)
LC #42 Pipers Alley

View Full Version : robot arm problem

04-15-2008, 11:37 AM
hey there!
i'm rigging a robot arm and i got some problems. if you check the attached screenshot you'll see my problem. i want to have an arm which has 2-axis-fixed rotations at each hinge.
the main problem is the change of axis at the 4th joint. if i switch the degrees of freedom off (xy or yz) the joints do what they should but the 4th joint is not solved... the same happens if i do a rotation limit.
any ideas how to solve this?
is it possible to solve this with an ik-setup? or do i have to you fk?

04-19-2008, 11:15 PM
this can be done easily, but not with the standard rotate-plane-ik-solver
you have to use the so called multichainsolver for things like this ...

type "ikMCsolver" and change the ik-solver on the ik-handle to that one
this should produce the results you want ;-)

cheers, ferdo

04-19-2008, 11:16 PM
sorry, you have to type:
createNode ikMCsolver;

04-20-2008, 07:29 AM
Thanks for your reply!
I tried that but the result seemed to be kind of instable and unpredictable. The solution I'm using now is a splitted ik-chain. So it's always one chain for xRot -> zRot -> zRot ... By parenting the ik-handles I got a pretty good result.

04-20-2008, 10:19 AM
well, you are right, this solver produces a complete different solution than the rotate-plane-solver. because it is able to "break" the chain, you would also have to limit the rotate channels for this solver to work like you would expect it.

CGTalk Moderation
04-20-2008, 10:19 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.