View Full Version : robot arm problem

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

04 April 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 April 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 April 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.