[ros-users] multi_dof_joints parameter in arm_navigation stack

Felix Meßmer Felix_Messmer at web.de
Wed Feb 2 12:09:08 UTC 2011

Dear community,

there is another feature in the unstable/diamondback version of the arm_navigation stack that I have problems with:
the multi_dof_joints parameter-option!

When I use our old launch file (cob_arm_navigation/cob3_planning_environment.launch) that loads the collision_checks and planning_groups paramters to the parameter server, I get the following error message from both the trajectory_filter and the ompl_planning node:

[ WARN] [1296646033.585385464]: No multi dof joints specified, including root to world conversion
[ WARN] [1296646033.585623806]: Can't do anything without a root transform

I've adapted the planning_environment.launch file to also load the multi_dof_joints parameter (looking at the according pr2-config files).
But now planning reqest as in move_arm_simple_pose goal fail due to the following error message from the environment_server node and the move_arm action server node:

[ WARN] [1296647088.916018038, 830.563000000]: No joint with name floating_trans_x
[ WARN] [1296647088.916446633, 830.563000000]: Joint limits violated.

[ERROR] [1296647088.925356070, 830.563000000]: Will not plan to requested joint goal since it violates joint limits constraints

The multi_dof_joints.yaml file I use looks like this:

    - name: base_joint
      type: Floating
      parent_frame_id: base_footprint #odom_combined
      child_frame_id: base_footprint

I guess the multi_dof_joint parameter is meant to introduce a joint that stands for the moving platform with 3 DoFs (trans_x, trans_y, rot_z)
Does that mean that if the pose goal is specified in a world/global coordinate system, the planner also considers and calculates a possibly necessary platform motion to reach the specied goal?

Is there a parameter (use_multidof?) for the environment_server to deactivate multi_dof_joints?
What else do I have to add to use that feature?

I hope you can give me a short explanation on that. Thanks a lot!

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