[SOLVED] Problem when running SoftRobots tutorial

[nicklj]

After I build SOFA from scratch together with SoftRobots and STLIB plugins (all master branch on the date of July 2), I met some problem when running the tutorial case located in SoftRobots/docs/tutorials/CableGripper/details
$ runSofa cablegripper.pyscn
The program can run, and the main sofa window can appear. However, there is ERROR information as:

[ERROR]   [TetrahedronSetTopologyContainer(container)] Cannot find edge 0 [28, 77] in triangle 0
[ERROR]   [TetrahedronSetTopologyContainer(container)] Cannot find edge 0 [28, 77] in triangle 0
[WARNING] [TetrahedronSetTopologyContainer(container)] TrianglesAroundEdge buffer can't be created as EdgesInTriangle buffer creation failed.
[ERROR]   [TetrahedronSetTopologyContainer(container)] Cannot find triangle 0 [140, 113, 125] in tetrahedron 0
[ERROR]   [TetrahedronSetTopologyContainer(container)] Cannot find triangle 0 [140, 113, 125] in tetrahedron 0
[WARNING] [TetrahedronSetTopologyContainer(container)] TetrahedraAroundTriangle buffer can't be created as trianglesInTetrahedron buffer creation failed.
[WARNING] [CableConstraint(CableConstraint)] An old implementation of CableConstraint was not allowing negative force. This is now possible. However, to limit the force to be strictly positive you now have to set minForce=0.

The same information repeated 3 times as there are three fingers. I found this seems to be the problem when SOFA read vtk meshes. Then I use gmsh to convert the .vtk mesh to .msh format (only support version 2, but not version 4), and change volumeMeshFileName to the msh file. Then the error disappears.

Then, no matter use vtk file (with errors), or use msh file (without errors), the gripper can correctly move, but cannot use ctrl+ to grasp. The fingers can interact with brick, but just directly penetrate the plate surface.

Sorry for all these chaos information. Some of them maybe caused by SOFA, some of them maybe caused by SoftRobots/STLIB, or may because I still did not setup the software correctly. So would appreciate if anyone may help me to figure it out.

[Hugo]

Hey @nicklj

I am no expert from SoftRobot, but I just poked the SoftRobot devs! The community should get back to you!
Cheers

Hugo

[Damien Marchal]

Hi @nicklj, hi hugo,

I will add that to my todo list.

[twxu]

Hi @nicklj, @Damien Marchal,

Sorry to add to an old post, but I am experiencing the same issue (after updating SOFA from v19.06 to v20.12). I see the exact same warning messages, but the scene still appears to work as it did before (using .VTK files).

Any updates on why these error messages appear?

[Hugo]

Dear @twxu

I would guess that your mesh has some issue (maybe duplicated edge). Could you check this ?
Best,

Hugo

[twxu]

Hi @Hugo,

Is there a way to check that inside SOFA? It seems ok when opened in Gmsh.
I’m also confused by this error because I only saw it appear after switching to v20.06 (the same scene opened in v19.06 did not show these errors).

[Hugo]

These checked were added by @epernod.
Could you confirm us Erik that these errors (see first post) come from issues in the mesh? could you tell us more?

Hugo

[epernod]

hi,

yes I saw that as well. Indeed the mesh file used in this tutorial need some cleanup. The errors notify that some topological element are not created but in this mesh they correspond to duplicated elements. This is not affecting the tutorial behavior.

I’ll clean it up when I have 2 mins.

best,

[beichun]

Hi,
I’m also having the same problem. Would like to hear any update! Is the mesh updated @epernod ?

[beichun]

Problem solved 🙂
I managed to convert the mesh, by converting the finger.stl to finger.msh using gmsh (needed to use format version 2, the default version 4 doesn’t work).

[Hugo]

great @beichun

It’s really good to hear that. I solve the topic then.
Best wishes,

Hugo

[Shaswat]

@beichun could you share the .msh file you created. The msh file created by converting stl to msh using Gmsh is having some errors.

If you could share the file you created, it would be helpful.

Regards
Shaswat Garg

[Hugo]

Yes and do not hesitate to PR them to the SoftRobots project @beichun!

Cheers

Hugo

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