[SOLVED] Collision detection algorithm and the algorithm to calculate the feedback force.

[Sen]

Hi,everyone
I have q question ,I would like to know the collision detection algorithm and the calculation of the feedback algorithm, and how to achieve in SOFA .
Thank you

[Hugo]

Hi Sen,

You have an example in the scene applications/plugins/Geomagic/scenes/Geomagic-FEMLiver.scn using a Geomagic haptic device. You will find the following collision pipieline:

<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"/>

and the object on which you wan to have force feedback will be like

<Node name="Instrument" >
        <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="@GeomagicDevice.positionDevice" template="Rigid" />
        <UniformMass name="mass" totalmass="0.005" />
        <LCPForceFeedback activate="true" forceCoef="0.005"/> <!-- ADDED : Compute a force-feedback for the device -->
        <UncoupledConstraintCorrection/>
</Node>

Hope this helps.

Hugo

[Sen]

Hi,
There are formulas or documents to how to explain or calculate it ?

[Hugo]

You can have a look at : https://www.researchgate.net/profile/Christian_Duriez/publication/221470428_Contact_Model_for_Haptic_Medical_Simulations/links/09e4150f46d3e29cbe000000.pdf

[Author]

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