Cooperative Robotic Arms?

asked 2011-07-20 11:48:58 -0500

Hello,

I am wondering if there is any ROS software developed or being developed for cooperative manipulator applications. For example, picking up large objects with two robotic arms. Currently, I have been experimenting with using move_arm software with our two 7-dof arms. Right now, I am sending separate goals (either joint position or pose) to each arm. Next, I would like to have cooperative motions, for example, both arms moving in unison. I have search throughout the ROS repositories and haven't found much (although I will continue looking). Any advice is greatly appreciated.

Cheers,
Jonathan

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I am currently working on a multi-arm pipeline for the PR2. It will take a while though for it to be ready for use. My current goal is to get it up and running by the end of the summer.

Sachin Chitta ( 2011-07-20 16:37:35 -0500 )edit

Thanks for your info Sachin. Looking forward to the multi-arm pipeline. For now I will uses Adolfo's advice.

Jonathan Realmuto ( 2011-07-21 03:09:33 -0500 )edit

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answered 2011-07-20 23:15:00 -0500

Adolfo Rodriguez T

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Jonathan,

This is already possible, at least up to some extent. We have been using joint space planners for planning simultaneous motions of two 7-dof arms since the boxturtle release of ROS. Works like a charm. It's all in how you setup the different planning groups. Also, make sure that you select a planner that is compatible with multiple endpoints. We've had good results with lazy RRTs.

Our usual workflow calls directly OMPL and the trajectory filters, but back in the day I tested it with the move_arm action as well. We never got around to exposing an IK solver for task space goals, but I don't see why that shouldn't be possible, and it's in our TODO list.

One thing we have not (yet) incorporated in our motion planning is torso joints. Since these joints are located before the arms branch out, shortcut smoother filters don't work well. In such cases, using a planner with optimality guarantees, like RRT* would be the way to go. Also, using a weighted distance metric would allow to favor motions of more distal joints over proximal ones.

@Sachin: What would be the scope of the multi-arm pipeline?.

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Thank you for your info Adolfo. I will begin apply your advice - using the RRT planner. I will let you know how it goes.

Jonathan Realmuto ( 2011-07-21 03:03:36 -0500 )edit

Hi Adolfo, This is still very preliminary but it will expose task space planning for carrying objects with two arms. It will also include joint space planners configured the way you mention to address two arms simultaneously for the part where the arms have to move in to grasp an object or move out of a grasp. BTW, its cool you got this working way back in boxturtle!

Sachin Chitta ( 2011-07-21 04:57:24 -0500 )edit

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