[Nguyen]

something like this:

<EulerImplicit name="cg odesolver" printLog="false" rayleighStiffness="0.01"  rayleighMass="1"/>
 <CGLinearSolver iterations="100" name="linear solver" threshold="1e-20" tolerance="1e-20" />
 <MechanicalObject template="Rigid3d" name="instrumentState" position="10 10 10 0 0 0 1 10 10 10 0 0 0 1 10 10 10 0 0 0 1 10 10 10 0 0 0 1" free_position="10 10 10 0 0 0 1 10 10 10 0 0 0 1 10 10 10 0 0 0 1 10 10 10 0 0 0 1"/>  
 <UniformMass template="Rigid3d" name="mass"  totalmass="0.1" />
 <LCPForceFeedback activate="true" tags="Omni1" forceCoef="0.5" /> 

[Nguyen]

I know this problem.

You have to set free_position in the MechanicalObject in your scene file. This MechanicaObject is mapped to your haptic via tagging i.e. using the same tag as OmniDriver.

In old version, sofa initialize free_position for you, now it doesnt.

[Nguyen]

I made a mistake. It’s addContact, not createContact.

Now, I solved the problem. The solution is to use GenericSolver (or similar name) instead of LCPSolver. The interesting thing is when I create a scene with BilateralInteractionConstraint statically, it works with LCPSolver but does not work dynamically i.e. added and removed by C++ code. I guess, LCPSolver needs to be refreshed whenever constraints are changed.

By the way, could you explain for me the differences between Generic and LCP ?

Thanks a lot !

[Nguyen]

Hi Hugo,

Thank you for your kind support.

Now, I can create the BilateralInteractionConstraint. I follow the code in the class StickContactConstraint. However, I sill have a problem that the haptic tool tip is not sticked to the object even though there is a interaction. What I dont understand is the function createContact in the class BilateralInteractionConstraint with many parameters and I dont understand the meaning of some parameters.

I am wondering if the BilateralInteractionConstraint only works with RigidMapping and IdentityMapping and does not work with BarycentricMapping ?

Any help is so much appreciated !

Thanks,
Thien.

[Nguyen]

Thank you all,

I was succeeded in creating a spring between the haptic tool and the collided point on the object. I used ContactMapper to create MechanicalState, then create a spring, then add the spring to the corresponding MechanicalState.

Now, instead of creating the spring, I create the BilateralInteractionConstraint, but it doesnt work.

[Nguyen]

I commented out the part that extracts quad mesh from hex mesh, then the scene worked fine and I can visualize force-field.

I am using old version (last year) of SOFA.

[Nguyen]

I have just modified the caduceus scene file by replace the snake by my object with some fixed points. I pull the object by mouse. When my object moves through the cylinder, i.e. collision resolve is failed, then some fixed points start floating around.

[Author]

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