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View Full Version : Arm inverse kinematics question: ignoring pose orientation



Pi Robot
12-13-2010, 09:17 PM
Seems there are a few of us working on ROS and arm kinematics. I have a question about using the arm_kinematics package by David Lu found at:

http://www.ros.org/wiki/arm_kinematics

So far I have everything working using the ArbotiX for controlling the AX-12 servos in my arm and I am playing with moving the finger tip on the left arm to a desired location in Cartesian space relative to the base of the torso. My question is this: Suppose I don't care about the orientation of the hand when moving the finger tip to the desired location. Is there a way to specify a "don't care about orientation" value as part of the pose specification in the request to the get_ik service? I ask because while it is easy for me to eyeball a desired location of the finger tip, it is less obvious how to measure a desired orientation of the hand.

BTW, I'm not doing anything with trajectories at this point as I haven't yet read up on that topic. For now I'm just trying to place the tip of the hand at different locations.

Thanks!
patrick

Pi Robot
12-13-2010, 11:31 PM
I'm starting to think my question above doesn't really make sense since the IK solver has to choose *some* orientation for the desired pose or it won't be able to converge to a solution. So I have picked a few easy-to-visualize orientations for the hand and a desired location and so far it seems to be working A-OK.

--patrick