Path Planning using moveIt with a closed-loop chain

Question

Hi everyone,

I am working on an robot arm which happens to be a closed-loop kinematic chain. I achieved to have a somewhat accurate simulation with gazebo7.

Now I have installed ros Indigo and I want to do some path planning with moveIt, and view it with rViz. So, I set up my robot to get the .sdrf file and everything works... except when I close my loop with the last joint.. The simulation doesnt take into account this joint.

When I check the shell it tells me that:

[ERROR] [1469600994.580670671]: Joint 'lely_arm__verin2/base' not found in model 'origins'

also:

[ERROR] [1469601613.254367292]: Kinematics solver N21srv_kinematics_plugin19SrvKinematicsPluginE does not support joint group g.  Error: This plugin only supports joint groups which are chains

Is it plain impossible to work on a closed loop or did i miss something?

Thank you very much

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Originally posted by Soho_ on ROS Answers with karma: 11 on 2016-07-27

Post score: 0

Answer 1

moveIt and rViz rely on URDF which does not support closed kinematic chains. See this discussion: http://answers.ros.org/question/9050/using-ros-for-a-delta-robot/?answer=13094#post-id-13094

People seem to work around this by opening the loop and then closing it using their own constraints.

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Originally posted by patrick_hammer with karma: 283 on 2016-08-08

This answer was ACCEPTED on the original site

Post score: 0

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Original comments

Comment by Soho_ on 2016-08-15:
I don't understand how sould I add these constraints It seems you can bypass the problem with clever solution for parellel robots, however it is not one here..