Moveit: Collision sometime with the ground

[Deastan]

Hello everyone,

My environment

ROS Distro: [Indigo]
OS Version: e.g. Ubuntu 14.04
Source or Binary build?
If binary, which release version? install with : sudo apt-get install ros-indigo-moveit => ros-indigo-moveit is already the newest version.

Gazebo 7 (before Gazebo 2.2 and also the same issue)

Do someone has an idea why the robot collides with the ground using moveit ? I am doing reinforcement learning and everything is working well except that part. I can go everywhere I need to go in cartesian space or using joint space. The end is working well too.
But sometime when I work close to the ground and go from (x = 0.5, y = 0.1, z = 0.1) to (x = 0.5, y = 0.2, z = 0.1), it touch the ground. The robot then (a kuka iiwa lbr 7) deformed itself with the constraint and finally reach the point in more than 5 to 10 sec. I know it can reach those points with others paths but I don't understand why it take this one.
I am working (unfortunately) on Ubuntu 14, with ROS indigo. I am using as solver: RRTkConfigDefault or maybe a bit better RRTConnectkConfigDefault.

Normally the robot looks like that:

I can give you more information if you need it.

Kind regards,

Jonathan

[welcome[bot]]

Thanks for reporting an issue. We will have a look asap. If you can think of a fix, please consider providing it as a pull request.

[gavanderhoorn]

Do you model your environment in your urdf / does MoveIt 'know' there is a ground plane there?

[Deastan]

Seriously ? Is it so simple and me so s...pid ? :D
I should do it by adding in the Step 3: Add Virtual Joints of the setup assistant? Or how can I do in the URDF file ?
Bur I had set the workinspace with z >0...

[gavanderhoorn]

How do you expect the planners to 'know' about any obstacles if the robot is simply floating in empty space in the description that you give them?

Or how can I do in the URDF file ?

Add a flat box under the robot?

[gavanderhoorn]

I'm going to close this as it's likely to be a user-side configuration issue.

If it's not, we can re-open.

Feel free to keep commenting on the issue of course.

[Deastan]

Thank you very much for you answer! I am really sorry for this kind of mistake.
To anyone, it is working now!

[gavanderhoorn]

I am really sorry for this kind of mistake.

no need to apologise.