Robot collision after adding things to the planning scene

[Joris Beuls]

Hello,

I am using an epson C3 robot for object collision in Moveit. After i add an octomap and a square to the planning scene, my robot collides with itself. What could the issue be?

Should anyone have a correct URDF of this robot it would also be appreciated so i can check if this the problem.

Best regards
Joris

[Yoan Mollard]

Hi Joris,

Check in the "Status" tab what the colliding links are.

If the problem is indeed that several adjacent links collide together, you can easily add a new rule in the SRDF of your robot to disable collisions between them 2 by 2 , something like:
<disable_collisions link1="name_link_1" link2="name_link_2" reason="Adjacent" />

You can also check if this is due to the collision model (in the URDF this time) is erroneous by displaying it in MoveIt: uncheck "show robot visual" and check show robot collision" in the "Scene robot" parameter of the Motion Planning plugin). If collision model is made of Collada meshes instead of basic shapes (cylinders and cubes), I know that some people experienced issues regarding their axes also, the consequence was that impossible collisions appeared.

Best,

Yoan Mollard

Research engineer – 3rd hand project

INRIA Research center, Flowers lab

http://flowers.inria.fr/

http://3rdhandrobot.eu/

---

[Yoan Mollard]

Switching to "adjacent" from "never" won't change anything since this is just an indicative reason for disabling this collision, but I don't think it is actually used by whatever program.

Have you checked in the "status" tab what the collisions are? It was the first thing to do before changing the srdf ;-)

Best,

Yoan Mollard

Research engineer – 3rd hand project

INRIA Research center, Flowers lab

http://flowers.inria.fr/

http://3rdhandrobot.eu/

---

From: "Joris Beuls" <joris...@student.uhasselt.be>
To: "Yoan Mollard" <yoan.m...@inria.fr>
Sent: Wednesday, 1 April, 2015 3:18:21 PM
Subject: Re: Robot collision after adding things to the planning scene

Hello,

thank you for your reply, i adjusted my SRDF file to make them "adjacent" instead of "never". This didn't solve the problem.

After that i tried to check the collisions within Rviz like you described (see the added picture). The robot visualization i get then does not collide with itself. When i post nothing on the planning scene i can move the robot freely and it also does not collide.

Do you maybe have any idea what else might be wrong here? Or could it be that my program for loading the octomap onto the planning scene does something wrong? (i added this to the attach file)

Best regards

Joris

​

[Jon Weisz]

If you are using Collada based (dae, zae extensions) geometry files, try using blender to export them as stl files. I had the same problem with a Kinova Mico arm, and the culprit was the geometry files. I never resolved exactly what about them was broken, but there is definitely some problem with the collada parser. 

[Joris Beuls]

I checked the 'status' screen in rviz and the links of the robot are indeed colliding. (see fig.) I am using STL files. I did not make them so it could be that they are wrong. I guess the next thing to do is remake them myself?


​

[Andreas Bihlmaier]

Make sure your collision meshes are not only STL files,
but that they are _CONVEX_ meshes.
Hint: meshlab -> Remeshing, Simplification and Reconstruction -> Convex Hull works very well.

On Thu, Apr 02, 2015 at 09:16:42AM +0200, Joris Beuls wrote:
> I checked the 'status' screen in rviz and the links of the robot are indeed
> colliding. (see fig.) I am using STL files. I did not make them so it could
> be that they are wrong. I guess the next thing to do is remake them myself?
>
>
> ​
>

> 2015-04-01 22:35 GMT+02:00 Jon Weisz <signal...@gmail.com>:
>
> > If you are using Collada based (dae, zae extensions) geometry files, try
> > using blender to export them as stl files. I had the same problem with a
> > Kinova Mico arm, and the culprit was the geometry files. I never resolved
> > exactly what about them was broken, but there is definitely some problem
> > with the collada parser.
> >
> >
> > On Wednesday, April 1, 2015 at 4:37:44 AM UTC-4, Joris Beuls wrote:
> >>
> >>

> >> <https://lh3.googleusercontent.com/-vrMVUA3OvbE/VRuuN4ns-dI/AAAAAAAAAB0/I3Yys_9H5v8/s1600/Fault%2B2.png>
> >>
> >>
> >> <https://lh3.googleusercontent.com/-Gfotl9Ws_M4/VRuuK3FZXXI/AAAAAAAAABs/Fd2rdvM_rjY/s1600/fault%2B1.png>

[Joris Beuls]

Thank you for the reply. I tried that but now it looks ugly and collides everywhere. (See images)

If someone could make a proper tutorial for new ROS users, it would be greatly appreciated. Learning ros on your own is very hard. I am currently writing a guide myself for all the problems that i solve.

Best regards

Joris

​

[G.A. vd. Hoorn - 3ME]

On 02/04/15 15:30, Joris Beuls wrote:
> Thank you for the reply. I tried that but now it looks ugly and collides
> everywhere. (See images)

Your meshes have their normals all over the place.

Use meshlab to get all normals to point outwards. That will fix the 'holes'.

Convex hulls can be slightly larger than the normal STLs, so you'll have
to redo / update your moveit pkg after you've changed them.

Also, use the convex hulls _only_ for the collision geometry.

> If someone could make a proper tutorial for new ROS users, it would be
> greatly appreciated. Learning ros on your own is very hard. I am currently
> writing a guide myself for all the problems that i solve.

There are plenty of books about ros. See [1] for an incomplete list.


> Best regards
> Joris


Gijs


[1] http://wiki.ros.org/Books

[ariyan kabir]

Hi Joris, 

We have a Epson C3 in our lab and I would like to do some experiments in simulation with it. I would highly appreciate if you could share the cad models, urdf, FK/IK package, and other packages that you designed to simulate this robot. 

Do you maintain any repository? Otherwise, could you please e-mail them to me? 

Thanks,

Ariyan

Graduate Student

University of Southern California

[G.A. vd. Hoorn - 3ME]

On 5-10-2017 6:01, ariyan kabir wrote:
> Hi Joris,
>
> We have a Epson C3 in our lab and I would like to do some experiments in
> simulation with it. I would highly appreciate if you could share the cad
> models, urdf, FK/IK package, and other packages that you designed to
> simulate this robot.
>
> Do you maintain any repository? Otherwise, could you please e-mail them to
> me?

Not the (exact) packages that were created by Joris, but somewhat later
versions may be found at [1].

This is ongoing work, so if you find something not working for you, do
please report and open an issue.


Gijs

[1] https://github.com/gavanderhoorn/epson_experimental

> On Wednesday, April 1, 2015 at 1:37:44 AM UTC-7, Joris Beuls wrote:
>>
>>

>> <https://lh3.googleusercontent.com/-vrMVUA3OvbE/VRuuN4ns-dI/AAAAAAAAAB0/I3Yys_9H5v8/s1600/Fault%2B2.png>
>>
>>
>> <https://lh3.googleusercontent.com/-Gfotl9Ws_M4/VRuuK3FZXXI/AAAAAAAAABs/Fd2rdvM_rjY/s1600/fault%2B1.png>