Cannot inflate or deflate a sphere balloon

[gurkanozhan]

I am trying to develop a simulation that inflates and deflates a ballon. My ultimate goal is to use this balloon its an angioplasty balloon catheter. However; I could not achieve any inflation animation so far, I have a 2 cm diameter tetrahedron sphere mesh with 5120 elements and a corresponding sphere surface consisting of triangles. In Sofa GUI I can see the ball sphere, but when I click Animate no inflation or any movement is observed. However, my logs show I am applying a varying amount of pressure at each step. I have been struggling with this for a long tome. Any help is much appreciated. Below is my source file:

import Sofa
import Sofa.Core

def createScene(rootNode):
    rootNode.name = "SurfaceBalloonInflation"
    rootNode.gravity = [0.0, 0.0, 0.0]
    rootNode.dt = 0.01

    # Required plugins
    rootNode.addObject("RequiredPlugin", pluginName="Sofa.Component.IO.Mesh Sofa.Component.Topology.Container.Dynamic Sofa.Component.Mass Sofa.Component.StateContainer Sofa.Component.MechanicalLoad Sofa.Component.SolidMechanics.FEM.Elastic Sofa.Component.Constraint.Projective Sofa.Component.ODESolver.Backward Sofa.Component.LinearSolver.Iterative Sofa.Component.Visual Sofa.GL.Component.Rendering3D SoftRobots")

    rootNode.addObject("DefaultAnimationLoop")
    rootNode.addObject("VisualStyle", displayFlags="showVisual")

    # Solver
    rootNode.addObject("EulerImplicitSolver")
    rootNode.addObject("CGLinearSolver", iterations=25, tolerance=1e-9)

    # Balloon
    balloon = rootNode.addChild("Balloon")
    balloon.addObject("MeshGmshLoader", name="loader", filename="meshes/sphere.msh")
    balloon.addObject("TetrahedronSetTopologyContainer", src="@loader")
    balloon.addObject("TetrahedronSetTopologyModifier")
    balloon.addObject("TetrahedronSetGeometryAlgorithms")
    balloon.addObject("MechanicalObject", name="dofs")
    balloon.addObject("UniformMass", totalMass=0.1)
    balloon.addObject("TetrahedralCorotationalFEMForceField", youngModulus=1500, poissonRatio=0.3)

    # Surface
    surface = balloon.addChild("Surface")
    surface.addObject("MeshOBJLoader", name="loader", filename="meshes/sphere_surface.obj", triangulate=True)
    surface.addObject("TriangleSetTopologyContainer", src="@loader")
    surface.addObject("TriangleSetTopologyModifier")
    surface.addObject("TriangleSetGeometryAlgorithms")
    surface.addObject("MechanicalObject", name="surfaceDOFs")
    surface.addObject("SurfacePressureConstraint", name="pressure", pressure=1.0, triangles="@loader.triangles")

    surface.addObject("BarycentricMapping", input="@../dofs", output="@surfaceDOFs")

    # Visual
    vis = balloon.addChild("Visual")
    vis.addObject("OglModel", name="visual", src="@../loader", color=[1.0, 1.0, 0.7, 1.0], texturename="meshes/balloon_texture.jpg")
    vis.addObject("MechanicalObject", name="visualDOFs")
    vis.addObject("BarycentricMapping", input="@../dofs", output="@visualDOFs")

    # Controller for stepwise inflate-deflate
    class InflateController(Sofa.Core.Controller):
        def __init__(self, node, constraint):
            super().__init__()
            self.node = node
            self.constraint = constraint
            self.pressure = 0.0
            self.inflating = True

        def onAnimateBeginEvent(self, event):
            if self.inflating:
                self.pressure += 0.05
                if self.pressure >= 5.0:
                    self.inflating = False
            else:
                self.pressure -= 0.05
                if self.pressure <= 0.0:
                    self.inflating = True

            self.constraint.findData("pressure").value = self.pressure
            print(f"[Controller] Pressure = {self.pressure:.2f}")

    surface.addObject(InflateController(surface, surface.pressure))

[hugtalbot]

Hi @gurkanozhan

Have you taken a look at this example in the public SoftRobots plugin : SurfacePressureConstraint.py

It should perform the de/inflation you are looking for.
Best wishes

[github-actions[bot]]

⚠️ ⚠️ ⚠️
@gurkanozhan
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding

[github-actions[bot]]

⚠️ ⚠️ ⚠️
@gurkanozhan
In accordance with our forum management policy, the last reply is more than 4 months old and is therefore closed. Our objective is to keep the forum up to date and offer the best support experience.

Please feel free to reopen it if the topic is still active by providing us with an update. Please feel free to open a new thread at any time - we'll be happy to help where and when we can.