Penetration model problem

[zhanglepy]

hello,
I am a graduate student and I am using Sofapython3 to achieve contact compression between rigid and soft bodies. If a rigid ball generated by SphereCollisionModel is used, it can allow the software to make normal contact and deformation. However, if a self created model is imported, there may be a problem of rigid bodies penetrating the software. The version I am using is SOFA23, and the following file is my program. Please provide more guidance, thank you!

code.zip

[zhanglepy]

This is the program I wrote for your guidance. Thank you
code.zip

[zhanglepy]

Hello everyone, I have already avoided grid penetration by root.addObject('MinProximityIntersection', useLineLine=True, usePointPoint=True, alarmDistance=0.001, contactDistance=0.0004, useLinePoint=True) change to root.addObject('MinProximityIntersection', useLineLine=True, usePointPoint=True, alarmDistance=0.004, contactDistance=0.002, useLinePoint=True)。 This method of increasing contact distance can temporarily avoid grid penetration, but significantly reduce simulation speed. I don't know if there is a better way, thank you everyone!

[zhanglepy]

Hello everyone, there is another issue with the program above, which is that the rigid body will bounce back after squeezing the soft body. Even with clear position control, it cannot prevent the rebound. Therefore, I tried to modify the mass of the rigid body, such as changing Cube.addObject ('UniformMass', total Mass=1) to Cube.addObject ('UniformMass', total Mass=100), which significantly reduced the rebound problem. May I ask if there are other more effective methods to achieve precise rigid body position control? Thank you!

[hugtalbot]

I got it bouncing too, I only made some modif , mostly :

• making sure that the CollisionResponse is defined after the Intersection component
• decreasing a bit a the speed of the probe

sim_githu__r60_0003.mp4

If you want your object to be only moved through your Python script and undergo no forces, you can simply suppress the solvers from the node "Probe" and only control its position through the script. Here is an implem :

import Sofa.Core, SofaRuntime
import numpy as np
import Sofa.Gui,Sofa.Simulation
import csv
# Choose in your script to activate or not the GUI
USE_GUI = True

def main():
    root = Sofa.Core.Node("root")
    createScene(root)
    Sofa.Simulation.init(root)

    if not USE_GUI:
        for iteration in range(1000):
            Sofa.Simulation.animate(root, root.dt.value)
    else:
        Sofa.Gui.GUIManager.Init("myscene", "qglviewer")
        Sofa.Gui.GUIManager.createGUI(root, __file__)
        Sofa.Gui.GUIManager.SetDimension(1080, 1080)
        Sofa.Gui.GUIManager.MainLoop(root)
        Sofa.Gui.GUIManager.closeGUI()

class drawPositionAndForce(Sofa.Core.Controller):
    def __init__(self, *args, **kwargs):
        # 继承 Sofa.Core.Controller 的初始化方法
        Sofa.Core.Controller.__init__(self, *args, **kwargs)
        self.rootNode = kwargs.get("rootNode")

    def onAnimateBeginEvent(self, event):
        # Get the current rigid body positions
        position = self.rootNode.Probe.MechanicalCube.position.value

        # Make a copy of the position array to allow modification
        position_copy = np.copy(position)

        print(position[0][2])

        # Modify the position (simple upward movement along the Y axis)
        for i, p in enumerate(position_copy):
            if position[i][2] > 0.05:
                position_copy[i][2] -= 0.0001  # Change only the y coordinate
                print('Current position z:', position[i][2])
            else:
                position_copy[i][2] == 0.05 # Keep position
                print('stop:', position[i][2])
            # position_copy[i][0] -= 0.0001

        # Assign the updated position back to the particle's position
        self.rootNode.Probe.MechanicalCube.position.value = position_copy


def createScene(root):
    root.gravity=[0, 0, 0]
    root.dt = 0.02
    root.addObject("RequiredPlugin", pluginName=[
                                                 'Sofa.Component.Collision.Detection.Algorithm',
                                                 'Sofa.Component.Collision.Detection.Intersection',
                                                 'Sofa.Component.Collision.Geometry',
                                                 'Sofa.Component.Collision.Response.Contact',
                                                 'Sofa.Component.Constraint.Projective',
                                                 'Sofa.Component.IO.Mesh',
                                                 'Sofa.Component.LinearSolver.Iterative',
                                                 'Sofa.Component.Mapping.Linear',
                                                 'Sofa.Component.Mass',
                                                 'Sofa.Component.ODESolver.Backward',
                                                 'Sofa.Component.SolidMechanics.FEM.Elastic',
                                                 'Sofa.Component.StateContainer',
                                                 'Sofa.Component.Topology.Container.Dynamic',
                                                 'Sofa.Component.Visual',
                                                 'Sofa.GL.Component.Rendering3D',
                                                 'Sofa.Component.AnimationLoop',
                                                 'Sofa.Component.LinearSolver.Direct',
                                                 'Sofa.Component.MechanicalLoad',
                                                 'Sofa.Component.Engine.Select',
                                                 'Sofa.Component.Constraint.Lagrangian.Correction',
                                                 'Sofa.Component.Constraint.Lagrangian.Solver',
                                                 'Sofa.Component.Engine.Transform',
                                                 'Sofa.Component.Topology.Mapping',
                                                 # 'Sofa.Component.Visual',  # 用于可视化
    ])
    # root.addObject('VisualStyle',
    #                displayFlags="showVisual showCollisionModels showWireFrame showForceFields")
    root.addObject('VisualStyle', displayFlags="showVisual showCollisionModels showWireframe showForceFields")
    root.addObject('FreeMotionAnimationLoop')
    root.addObject('GenericConstraintSolver', name="GCS", maxIterations=1000, tolerance=1e-6,
                   computeConstraintForces="1")  # 添加通用约束求解器
    root.addObject('CollisionPipeline', name="CollisionPipeline")
    root.addObject('BruteForceBroadPhase', name="BroadPhase")
    root.addObject('BVHNarrowPhase', name="NarrowPhase")
    root.addObject('MinProximityIntersection', useLineLine=True, usePointPoint=True, alarmDistance=0.001, contactDistance=0.0004, useLinePoint=True)
    root.addObject('CollisionResponse', name="CollisionResponse", response="FrictionContactConstraint")

    Breast = root.addChild('breast')
    Breast.addObject('EulerImplicitSolver', name="cg_odesolver", rayleighStiffness=0.1, rayleighMass=0.1)
    Breast.addObject('SparseLDLSolver', name="linear_solver", template="CompressedRowSparseMatrixMat3x3d")
    Breast.addObject('MeshGmshLoader', name="meshLoader", filename=r"v.msh", scale3d =[1,1,1])
    Breast.addObject('TetrahedronSetTopologyContainer', name="topo", src="@meshLoader")
    Breast.addObject('MechanicalObject', name="dofs", src="@meshLoader", showObject=1)
    canshu = Breast.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3d", name="GeomAlgo")
    Breast.addObject('UniformMass', totalMass="0.00003")  # 添加统一质量组件
    # liver.addObject('DiagonalMass', name="Mass", massDensity=1.0)
    Breast.addObject('TetrahedralCorotationalFEMForceField', template="Vec3d", name="FEM", method="large",
                    poissonRatio=0.49, youngModulus=2000, computeGlobalMatrix=False)

    Breast.addObject('BoxROI', name="segment1", box="-0.52 -0.04 -0.00 -0.38 0.07 0.015", drawBoxes="True")
    Breast.addObject('FixedConstraint', name="FixedConstraint", indices="@segment1.indices")
    Breast.addObject('LinearSolverConstraintCorrection')

    BreastSurf = Breast.addChild('ExtractSurface')
    BreastSurf.addObject('TriangleSetTopologyContainer', name="Container", position="@../topo.position")
    BreastSurf.addObject('TriangleSetTopologyModifier', name="Modifier")
    BreastSurf.addObject('Tetra2TriangleTopologicalMapping', name="SurfaceExtractMapping", input="@../topo",
                        output="@Container")
    BreastCollision = BreastSurf.addChild('Surf')
    BreastCollision.addObject('TriangleSetTopologyContainer', name="Container", src="@../Container")
    BreastCollision.addObject('MechanicalObject', name="surfaceDOFs")
    BreastCollision.addObject('TriangleCollisionModel', name="CollisionModel")
    BreastCollision.addObject('PointCollisionModel', name="CollisionModel")
    BreastCollision.addObject('IdentityMapping', name="CollisionMapping", input="@../../dofs", output="@surfaceDOFs")

    Cube = root.addChild('Probe')

    Cube.addObject('MeshGmshLoader', name="meshLoaderCube",filename=r"sphere01_v.msh",rotation='180 0 0')
    Cube.addObject('MechanicalObject', showObject = 0, name='MechanicalCube', template='Rigid3d',
                   position=[-0.463,  0.017 , 0.043053+0.05, 0, 0, 0, 1])

    # Cube Visual Model
    VisuCube = Cube.addChild('VisuCube')
    VisuCube.addObject('OglModel', name="VisuCube", src="@../meshLoaderCube", color="0.9 0.6 0.6")
    VisuCube.addObject('RigidMapping', name="VisuMapping", input="@../MechanicalCube", output="@VisuCube")

    # Cube Collision Model
    ColliCube = Cube.addChild('ColliCube')
    ColliCube.addObject('MeshTopology', src="@../meshLoaderCube")
    ColliCube.addObject('MechanicalObject', name="ColliCubeMe")
    ColliCube.addObject('TriangleCollisionModel', name="Cube Triangle for Collision", simulated="1", moving="1")
    ColliCube.addObject('LineCollisionModel', name='Cube Line for Collision', simulated="1", moving="1")
    ColliCube.addObject('PointCollisionModel', name="Cube Point for Collision", simulated="1", moving="1")
    ColliCube.addObject('RigidMapping', name="CollisionMapping", input="@../MechanicalCube", output="@ColliCube")

    DrawPositionAndForce = drawPositionAndForce(name="RigidBodyController", rootNode=root)
    root.addObject(DrawPositionAndForce)



    return root

# Function used only if this script is called from a python environment
if __name__ == '__main__':
    main()

[github-actions[bot]]

⚠️ ⚠️ ⚠️
@zhanglepy
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]]

⚠️ ⚠️ ⚠️
@zhanglepy
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.

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