Biped (Dual Arm) planning in MoveIt - How to?

asked 2014-10-10 22:28:59 -0500

Anonymous

Hi All,

I have a dual arm biped system as shown in MoveIt here: image description

The system works by having one arm grasping a support whilst the other reaches out for another. Switching between the two, locomotion is carried out.

The problem i have is that I have only been able to move the robot from the same gripper, i can't switch which one is stationary from which the rest of the joints should be calculated.

How can I plan trajectories for this system?? I intended to plan from one gripper, obtain a new support, change the fixed gripper to the other side, the plan again from this new point.

Any help is much appreciated.

Regards,

Chris.

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I haven't used Moveit! much but have you tried making two separate move groups? E.g. one's base link is one gripper, and the other's base link is the other gripper.

Airuno2L ( 2014-10-11 15:40:05 -0500 )edit

Given that this system actually matches the legs of a humanoid biped from the waist down, is it possible to use their approach? How do users do planning for the humanoids?

Anonymous ( 2014-10-16 16:16:50 -0500 )edit

I believe they do as I was suggesting, using different move groups.

Airuno2L ( 2014-10-20 07:57:19 -0500 )edit

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answered 2014-10-12 01:21:20 -0500

fergs

13902 ●59 ●157 ●196 http://www.robotandchisel.com

I don't think MoveIt, or even the underlying URDF/SRDF formats can actually describe this without at least some hacking.

If I had to do this, I think I would rely on an external "odometry" node that would track the position of the "base gripper" in the "world link" and output a TF transformation. When the base gripper is closed on something, the TF transform obviously would not change, however, when the other gripper is closed and the arm is moving, the transform would be updated based on how far the "base gripper" has moved. MoveIt would only ever have a single planning group, from the "base gripper" to the "other gripper" and (heres the other hacky part), when specifying a cartesian goal when the "other gripper" is closed, you would actually specify the inverse movement that you want to do with the "base gripper".

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Biped (Dual Arm) planning in MoveIt - How to?

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