[Shan]

Hi Hugo,

The scene seems to work now, I changed the mesh and I believe it was because the mesh for not refined properly that the Sofa scene was giving the error I mentioned above. So I guess the last query is resolved, however if you have any suggestions I would be happy to learn.

Best regards,
Shantanu.

[Shan]

Hi Hugo,

Thanks for the reply. I made the changes you suggested, however now I have the following error:-

[ERROR] [TetrahedronFEMForceField(FEM)] object must have a tetrahedric topology. The component is inactivated. To remove this error message please add a tetrahedric topology component to your scene.

I changed the mesh as well, made it finer for collision problem.

Regards,
Shan

[Shan]

Hi Hugo,

Thanks for the reply. I believe there could be the problem with the mesh. I generated the mesh using Gmsh. Do you have any suggestions, should I make the mesh finer for the collision simulation? I could also send you the geometry for you to check what is wrong with the mesh.

Best regards,
Shan.

[Shan]

Hi Hugo,

Thanks for the reply. Yes, I am getting the above mentioned warning in set3.pyscn in the FirstStep tutorial.

My apologies for the late reply, had some coursework to finish.

Best regrads,
Shan.

[Shan]

Hi Hugo,

Thanks for the reply. I granted you access to google drive, please check if you can access it.
Regarding the query about rigidification, I did go through the example you mentioned. However I am a bit confused regarding the arguments “indices” and “frames” as I am not sure how to extract it from mesh. The part I want to make rigid is the outer wall of the column so that it does not expand radially though it can still expand axially and also can bend.

I understand you guys must be busy with the upcoming events on SOFA training in November, though it would be really helpful if you could explain the functions in Python. I have gone through https://www.sofa-framework.org/api/master/sofa/html/index.html to understand the functions and classes used in SOFA Python, but its not really clear to me.

Looking forward to see you for the training session.

Best regards,
Shan

[Shan]

Hi,

I would be obliged if someone could advise me on the above mentioned query.

Regards,
Shan

[Shan]

Hi,

Also I have another question regarding the rigidification, what is the need for creating a simulationNode as given one of the topics in forum.

RigidMapping from Rigid3d to only some particles of FEMbody

simulationNode = rootNode.createChild(“Simulation”)
simulationNode.createObject(“EulerImplicitSolver”)
simulationNode.createObject(“CGLinearSolver”)
simulationNode.addChild(o)

Best regrads,
Shan

[Shan]

Hi,

I have been trying to work with tripod tutorial example to rigidify outer boundary of the cylindrical actuator I mentioned earlier. However I am stuck at extracting the “groupIndices” and “frame”. I would be highly obliged if you could help me out here. The code I implemented is as follows:

import Sofa
 import os

#from stlib.visuals import ShowGrid
from stlib.scene import MainHeader
from stlib.physics.deformable import ElasticMaterialObject
#from stlib.physics.constraint import FixedBox
from stlib.physics.mixedmaterial import Rigidify
from splib.objectmodel import setData

def createScene(rootNode):
        #Another way to add gravity with MainHeader
        MainHeader(rootNode, gravity=[0.0,0.0,-9810.0])
        #MainHeader(rootNode, plugins=["SofaSparseSolver"])
        rootNode.createObject('VisualStyle', displayFlags='showForceFields')
        rootNode.createObject('RequiredPlugin', name='soft', pluginName='SoftRobots')
        rootNode.createObject('RequiredPlugin', name='SofaPython', pluginName='SofaPython')

        rootNode.createObject('PythonScriptController', filename="pythonControllers/fingerController.py", classname="controller")
        rootNode.createObject('FreeMotionAnimationLoop')
        rootNode.createObject('GenericConstraintSolver', tolerance="1e-12", maxIterations="10000")

        # Create Actuator mechanical model

        finger = rootNode.createChild('finger')
        finger.createObject('MeshVTKLoader', name='loader', filename='data/mesh/TestActuator')
        finger.createObject('Mesh', src='@loader', name='container')
        finger.createObject('MechanicalObject', name='tetras', template='Vec3d',showObject='true', showObjectScale='1')
        #finger.createObject('SubsetMultiMapping', template='Vec3d', indices='1 2 3 100')
        finger.createObject('TetrahedronFEMForceField', template='Vec3d', name='FEM', method='large', poissonRatio='0.4',  youngModulus='1500', drawAsEdges="true")
        finger.createObject('UniformMass', totalMass='0.0008')
        finger.createObject('EulerImplicit', name='odesolver', rayleighStiffness='0.1', rayleighMass='0.1')
        finger.createObject('SparseLDLSolver', name='directSolver')
        #finger.createObject('CGLinearSolver', name='Solver')

        # tracking Mesh Nodes 1 2 5 6 8 10 50 55 60 100
        tracking = finger.createChild('tracking')
        tracking.createObject('MechanicalObject', showObject='true', showObjectScale='5')
        tracking.createObject('SubsetMapping', indices='1 2 5 6 8 10 50 55 60 100')
       
 # FixedBox constraint at the bottom of actuator

        finger.createObject('BoxROI', name='boxROI', box='-10.5 -10.5 -4.5 10.5 10.5 -2', drawBoxes='true', drawSize='0.1')
        finger.createObject('RestShapeSpringsForceField', points='@boxROI.indices', stiffness='1e12', angularStiffness='1e12')
        finger.createObject('LinearSolverConstraintCorrection', solverName='directSolver')

        # FixedBox constraint on top of actuator

        finger.createObject('BoxROI', name='boxROI1', box='-10.5 -10.5 82.5 10.5 10.5 86', drawBoxes='true', drawSize='0.1')
        finger.createObject('RestShapeSpringsForceField', points='@boxROI1.indices', stiffness='1e12', angularStiffness='1e12')
        finger.createObject('LinearSolverConstraintCorrection', solverName='directSolver')

        # Cavity of elastic cylinder (Actuator)

        cavity = rootNode.finger.createChild('cavity')
        cavity.createObject('MeshVTKLoader', name='loader2', filename='data/mesh/TestCavity')
        cavity.createObject('Mesh', src='@loader2', name='cavityMesh')
        cavity.createObject('MechanicalObject', name='cavity', showObject='true', showObjectScale='1')
        cavity.createObject('SurfacePressureConstraint', name="SurfacePressureConstraint", template='Vec3d', value="0.0001", valueType="pressure")
        cavity.createObject('BarycentricMapping', name='mapping', mapForces='false', mapMasses='false')

The meshed geometry is in this link
https://drive.google.com/drive/folders/1r3zk_WkzGLM0yhyyY7_W996jcpUx0akv?usp=sharing

Best regards,
Shan

[Shan]

Hi Cristian,

I looked at Tripod tutorial and also looked at the following example

https://github.com/SofaDefrost/STLIB/blob/master/python/stlib/physics/mixedmaterial/rigidification.py

However I have questions regarding “frames” and “groupIndices”. Could you please explain what do they mean in terms of the mesh. I looked at few topics on rigidification and it seems to me that it has to do with BoxROI. Since I am an amateur in python so I couldn’t completely understand the code so please pardon my lack of knowledge of python. I am unclear about how to rigidify the surface mesh elements of the the outer boundary of the cylindrical structure.
In short how can I obtain frames and indices from the meshed structure.

Best regards,
Shantanu.

[Shan]

Hi Christian,

Thanks for the suggestion. I will look into the tutorial example of Tripod to see how to implement “rigidification”. Hope to get back to you with some progress.

Cheers.
Shan

[Shan]

Thanks. I will update you if I am able to resolve the issue with your suggestion.

[Author]

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