Non-linear simulations & Voxels in Sofa

[Aditya]

I’ve been looking at simulating smart materials & I’m wondering if you have any plans for extending Sofa (or the Soft Robots plugin by DEFROST) for non-linear computation, and for intrinsic material properties that are possibly missed out right now? (because of sofa being inherently linear, I guess?)

Are you looking at working on something at a Voxel level (see github.com/jonhiller/Voxelyze) and extending (or maybe writing another plugin) on top of Sofa, for simulating smart materials?

[Damien Marchal]

Hi @Aditay

Thanks for your interest and questions.

I’m not expert in the plugin to use in Sofa to have non linear models. But you are wrong saying SOFA is inherently linear. SOFA (https://www.sofa-framework.org/) is a general purpose modeling framework for deformable mechanics and it is SOFA is not restricted to linear mechanics. Several plugins & components implements non-linear mechanics. But what is true is that most of the one we use are linear. I think you can find an example of use of non linear model in the recent’s Felix Vanneste’s paper available at https://hal.inria.fr/hal-02475589

Here are also few plugins that pops in my head:
– HighOrder plugin: https://github.com/sofa-framework/plugin.HighOrder
– Flexible plugin:https://www.sofa-framework.org/api/master/plugins/Flexible/html/index.html
– https://www.sofa-framework.org/applications/marketplace/tools-for-multi-material-simulations/

> Are you looking at working on something at a Voxel level (see
> https://github.com/jonhiller/Voxelyze) and extending (or maybe writing
> another library) on top of it, to simulate/control soft robots?

You can do voxels base simulation in SOFA by using the HexahedronFemForceField as well as its multi-resolution extensions (I think it is from this paper: https://hal.inria.fr/inria-00443064). The nice thing with this voxel implementation is that you can any geometrical shape in the voxel grid to have the correct geometry and a simplified mechanics.

In term of roadmap I think that two possible directions starting from that would be to:
– have an in-sofa voxel/implicit shape modeling editor mode to easily’paint’ the shape of the robot
– extends the voxel/octree’s version we have to cope with non-linear materials.

Maybe people like @hugotalbot or @jeannicolas could provide more information.

Regards,
Damien

[Hugo]

Hi @adityamulgundkar

Welcome on the SOFA! Glad to see that you already have a reply from Damien.
Note for next time: post rather in the sub-forum “Using SOFA” rather than the “Announcement/Information” one (I just moved it).

Could you tell us which non-linearity you are referring to? (material, geometric)

For materials, you can find the TetrahedronHyperelasticityFEMForceField which proposes usual non-linear laws (ArrudaBoyce, NeoHookean, MooneyRivlin, Costa, VerondaWestman, Ogden and also St Venant).
On the other hand, for geometry, Damien already pointed it out: a HighOrder plugin exist for this.

Finally, regarding Voxel approach, you can using the image plugin, and then generate grids that you can deform.

I hope this helps.
Best wishes,

Hugo

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