Trac IK joint positions beyond +/-180 degrees

asked 2020-12-14 05:32:20 -0600

Borkr gravatar image

Whenever I compute joint positions for a trajectory using TracIK, where one of the joints go above 180 degrees or below -180 degrees, TracIK seems to want to rotate that joint back to -179.99 or 179.99 and go on from there.

I understand this is practically the same solution in space, however, I have something attached to the end-effector that effectively makes this a closed kinematic chain. What is attached to the EEF is unable to follow the reconfiguration path.

Is it at all possible to use TracIK where it adheres to joint limits less than -180 and greater than 180 degrees?

I'm not using MoveIt, I use TracIK directly and compute my own paths.

This problem occurs either for the fourth or sixth joint of a KUKA KR6 R900 sixx.

A dirty solution that I can think of is to add some of my own magic between the trajectory generator and TracIK to add/subtract 360 degrees offset as appropriate for the joints in question.

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I would suggest to ask the TracIK maintainers on their issue tracker.

gvdhoorn gravatar image gvdhoorn  ( 2020-12-14 07:12:36 -0600 )edit