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IK succeed for constraint-aware but fail for non-aware

asked 2012-09-06 23:45:24 -0600

i'm following this tutorial http://ros.org/wiki/pr2_kinematics/Tutorials/Tutorial%204 to do the inverse kinematics for my robot arm. but for the same goal position, the constraint_aware_ik succeed to find a solution while the non constraint aware ik cannot. after dig into the source code, i find that the constraint_aware_ik ultimately call the function searchPositionIK() and the non-aware ik call the getPositionIK(). my kinematics solver is the KDLArmKinematicsPlugin. is there anybody encountering the same problem as me?

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answered 2012-09-07 01:29:02 -0600

Adolfo Rodriguez T gravatar image

Probably what's happening is that the IK solver is unable to evolve from the seed state you provide to the desired goal. The searchPositionIK() method performs retries (up to 3 by default) from randomly sampled seed states if the provided one fails, while getPositionIK() does not.

If you want to keep using getPositionIK(), choose a more appropriate IK seed state.

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thanks for the answer. i will try other seed states

yangyangcv gravatar imageyangyangcv ( 2012-09-07 15:11:06 -0600 )edit

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Asked: 2012-09-06 23:45:24 -0600

Seen: 216 times

Last updated: Sep 07 '12