How to completely prevent penetration when collision occurs?

[Wong]

I just simplify the .scn (as shown below) from an example in Geomagic plugin, but penetration still occurs sometimes when the instrument is manipulated to collide with the liver.
So how to more effectively prevent such penetration?

<Node name="root" dt="0.005" gravity="0 -9.81 0" >
    <VisualStyle displayFlags="hideBehaviorModels hideCollisionModels hideMappings hideForceFields" />
    <RequiredPlugin name="Geomagic plugin" pluginName="Geomagic" />
    
    <CollisionPipeline name="pipeline" depth="6" verbose="0"/>
    <BruteForceDetection name="detection" />
    <CollisionResponse name="response" response="FrictionContact" />
    <LocalMinDistance name="proximity" alarmDistance="0.15" contactDistance="0.05" angleCone="0.0" />
    <FreeMotionAnimationLoop/>
    <LCPConstraintSolver tolerance="0.001" maxIt="1000"/>
    <GeomagicDriver name="GeomagicDeviceL" deviceName="Default Device" tags="L" scale="1" forceScale="5" drawDeviceFrame="1" positionBase="-2 0 0" orientationBase="0 0 0 1"  />

    <Node name="Liver" gravity="0 -9.81 0">
        <EulerImplicitSolver name="cg_odesolver"  />
        <CGLinearSolver name="linear solver" iterations="25" tolerance="1e-09" threshold="1e-09" />
        <MeshGmshLoader name="meshLoader" filename="mesh/liver.msh" />
        <TetrahedronSetTopologyContainer name="topo" src="@meshLoader" />
        <MechanicalObject name="dofs" src="@meshLoader" dx="0"/>
        <TetrahedronSetGeometryAlgorithms template="Vec3d" name="GeomAlgo" />
        <DiagonalMass  name="computed using mass density" massDensity="1" />
        <TetrahedralCorotationalFEMForceField template="Vec3d" name="FEM" method="large" poissonRatio="0.3" youngModulus="6e3" computeGlobalMatrix="0" />
        <PrecomputedConstraintCorrection recompute="1"/>
        <BoxROI template="Vec3d" box="-3 1 -2 -1 3 3" drawBoxes="1" position="@dofs.rest_position" name="FixedROI" computeTriangles="0" computeTetrahedra="0" computeEdges="0" />
        <FixedConstraint template="Vec3d" name="default6" indices="@FixedROI.indices" />

        <Node name="Visu" tags="Visual" gravity="0 -9.81 0">
            <OglModel  name="VisualModel" fileMesh="mesh/liver-smooth.obj"  dx="0"/>
            <BarycentricMapping name="visual mapping" input="@../dofs" output="@VisualModel" />
        </Node>
        <Node name="Surf" gravity="0 -9.81 0">
            <MeshObjLoader name="meshLoader" filename="mesh/liver.obj"/>
	    <Mesh src="@meshLoader" />
	    <MechanicalObject name="spheres"  dx="0"/>
	    <Triangle group="0" name="ballT" contactStiffness="10"/>
	    <Line group="0" name="ballL" contactStiffness="10"/>
	    <Point group="0" name="ballP" contactStiffness="10"/>
            <BarycentricMapping name="sphere mapping" input="@../dofs" output="@spheres" />
        </Node>
    </Node>

    <Node name="InstrumentL" >
        <EulerImplicitSolver name="ODE solver" rayleighStiffness="0.05" rayleighMass="1.0" />
        <CGLinearSolver name="linear solver" iterations="25" tolerance="1e-10" threshold="10e-10" /> 
        <MechanicalObject name="instrumentState" position="@GeomagicDeviceL.positionDevice" template="Rigid" />
        <UniformMass name="mass" totalmass="0.005" />
        <LCPForceFeedback tags="L" activate="true" forceCoef="0.005"/> <!-- ADDED : Compute a force-feedback for the device -->
        <RestShapeSpringsForceField points="0" stiffness="10" angularStiffness="10"/> <!--external_rest_shape="toto"/>-->
        <UncoupledConstraintCorrection/>
        <Node name="VisualModel" >
            <OglModel name="InstrumentVisualModel" fileMesh="Demos/Dentistry/data/mesh/dental_instrument.obj" color="1.0 0.2 0.2 1.0" ry="-180" rz="-90" dz="3.5" dx="-0.3"/>
            <RigidMapping name="MM->VM mapping" input="@instrumentState" output="@InstrumentVisualModel" />
        </Node>
        <Node name="CollisionModel" >
            <MeshObjLoader filename="Demos/Dentistry/data/mesh/dental_instrument_centerline.obj"  name="loader"/>
            <Mesh src="@loader" name="InstrumentCollisionModel" />
            <MechanicalObject src="@loader" name="instrumentCollisionState"  ry="-180" rz="-90" dz="3.5" dx="-0.3" />
            <Line name="L" contactStiffness="10" />
            <Point name="P" contactStiffness="10" /> 
            <RigidMapping name="MM->CM mapping" input="@instrumentState" output="@instrumentCollisionState" />
        </Node>
    </Node>

</Node>

[Hugo]

Hi @outtt

Are you as specified in the topic info the v17.12?
Best,

Hugo

[Wong]

Hi @hugo,
Where is the topic info?

[Hugo]

It corresponds to information (“tag”) regarding your SOFA version and your operating system that you have to precise when creating a new topic (look juste down the topic title)

Well, what is your SOFA version then?

Best

Hugo

[Wong]

Hello @hugo,

Just V17.12, can you help me?

[Hugo]

Ok, it was just to check: some more recent version have issues with Geomagic. But v17.12 should be fine.

Have you tried to increase both the alarmDistance and contactDistance in the LocalMinDistance ?
If it does not solve your issue, I’ll test the scene with the Geomagic compiled on my machine.

Best,

Hugo

[Wong]

Hello @hugo,
Increasing both the alarmDistance and contactDistance is sure to be fine, but the animation would become slow. How to address this issue?

[Hugo]

Hi @outtt

if the simulation slows down, it means the computation becomes more complicated. Hard to make it more efficient. You can:
– decrease the refinement of your collision mesh
– try to increase the stiffness of your collision models

Let me know if this helps.
I did not use the Geomagic for some weeks. As soon as I use it again, I will give a try to your scene.

Best

Hugo

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