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moveit / moveit_ros

THIS REPO HAS MOVED TO https://github.com/ros-planning/moveit
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Fix broken frame transforms in moveit's rviz displays #669

Closed v4hn closed 8 years ago

v4hn commented 8 years ago

This makes using the displays with rviz a much nicer experience. :)

Now all moveit displays behave correctly when changing the fixed-frame in rviz to an end-effector.

The more common use-case where problems occurred is when moveit's planning frame is base_link of a mobile base, but the fixed-frame is map. Because this transform usually changes as the robot localizes itself, assuming a static transform is broke.

Please cherry-pick and release this fix into indigo as well! (If you prefer I can also create an additional pull request for that..)

rhaschke commented 8 years ago

Thanks for this fix.

rhaschke commented 8 years ago

While this series of fixes handles the correct display of the PlanningScene in rviz, I think there is a more fundamental problem: The frame_id of collision_objects is only used once at instantiation time. Later (tf) updates to the frames are ignored - in the PlanningScene everything is expressed w.r.t. the root model frame. Hence, if you have placed collision objects relative to map (because you know they are fixed), they will move together with the robot, when the transform from map to robot is updated.

@isucan Is there a TF-Updater plugin, which takes care of transform updates in the planning scene when tf frames do change?

v4hn commented 8 years ago

On Thu, May 19, 2016 at 07:51:14AM -0700, Robert Haschke wrote:

I think there is a more fundamental problem: The frame_id of collision_objects is only used once at instantiation time. Later (tf) updates to the frames are ignored

  • in the PlanningScene everything is expressed w.r.t. the root model frame.

Yes. I am rather sure this is deliberate and more of a modelling decision than a problem. To simplify computation, moveit works in its ModelFrame at all times. Therefore it expects things not to change with respect to it unless one MOVEs them. I would say, if you want your objects to stay constant w.r.t. a map frame, make it the ModelFrame. In theory one could maintain a list of frame-ids for the objects and update them, or postpone the transformation to the collision world. I'm not sure it's worth the effort though. Also, I think in this case there should be a mechanism such as visualization_msgs/Marker's frame_locked added. Otherwise, all objects you add in the mobile robot's camera frame would move around with the robot and that's probably not a good idea either.

Anyways, I'd say this is an independent feature request for moveit and has nothing really to do with this request that fixed the rviz plugins.