How to genuinely increase the friction in a frictionContact scene?

[Wong]

Hello everyone,

This problem has perplexed me for a long time. I notice that the frictionContact option in CollisionResponse is usually used in quite a number of default scenes in Sofa.

I try to increase the mu at many components, such as CollisionResponse, LCPConstraintSolver, and the collision model and use a grasper to grasp a deformable body. But no remarkable result can be seen after that.

And I notice this link provided a example scene to address the problem:

<Node name="root" dt="0.01" gravity="0 -9.81 0">
    <!– Basic Components to perform the collision detection –>
    <VisualStyle displayFlags="showBehavior showCollisionModels" />
    <CollisionPipeline />
    <BruteForceDetection />
    <FreeMotionAnimationLoop/>
    <GenericConstraintSolver maxIterations="1000" tolerance="0.001"/>
    <DefaultContactManager response="FrictionContact" responseParams="mu=0.6"/>
    <MinProximityIntersection alarmDistance="1" contactDistance="0.5"/>
    <!– Using a deformable cube using collision spheres  –>
    <Node name="Cube1">
        <EulerImplicitSolver name="EulerImplicit Cube1" />
        <SparseLDLSolver name="Solver Cube1" />
        <MechanicalObject name="Particles Cube1" template="Vec3d" position="0 0 1  1 0 1  0 1 1  1 1 1  0 0 2  1 0 2  0 1 2  1 1 2" translation="0.5 2 0" />
        <MeshTopology name="Topology Cube1" hexas="0 4 6 2 1 5 7 3" />
        <UniformMass name="Mass Cube1" totalmass="1" />
        <MeshSpringForceField name="Springs Cube1" stiffness="100" damping="1" />
        <!– Collision Models –>
        <SphereModel name="Spheres For Collision Cube1" radius="0.2" />
        <LinearSolverConstraintCorrection/>
    </Node>
    <!– Using a deformable cube using collision triangles, lines and points  –>
    <Node name="Cube2">
        <EulerImplicitSolver name="EulerImplicit Cube2" />
        <SparseLDLSolver name="Solver Cube2" />
        <MechanicalObject name="Particles Cube2" template="Vec3d" position="0 0 1  1 0 1  0 1 1  1 1 1  0 0 2  1 0 2  0 1 2  1 1 2" />
        <MeshTopology name="Topology Cube2" hexas="0 4 6 2 1 5 7 3" />
        <UniformMass name="Mass Cube2" totalmass="1" />
        <MeshSpringForceField name="Springs Cube2" stiffness="15" damping="1" />
        <!– Collision Models –>
        <TriangleModel name="Triangles For Collision" />
        <LineModel name="Lines For Collision" />
        <PointModel name="Points For Collision" />
        <LinearSolverConstraintCorrection/>
    </Node>
    <Node name="Floor">
        <MeshTopology name="Topology Floor" filename="mesh/floor.obj" />
        <MechanicalObject name="Particles Floor" />
        <TriangleModel name="Triangle For Collision Floor" moving="0" simulated="0" />
    </Node>
</Node>

But an error occurs:
[ERROR] [SparseLDLSolver] Failed to factorize, D(k,k) is zero

So what is the problem?

[Wong]

@hugo, could you give me a reply?

[Hugo]

Hey @outtt

have you checked Antonin’s input here ?
Best

Hugo

[Author]

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