problems of hinges (error reduction parameters)

[lovefoster]

hi!

I set a hinge (hinge3) between crank(pbodyD) and link(pbodyC),just look at my uploaded figure.

1.JPG

As the simulation proceeds the joint will gradually "come apart".i have tried, but i could not solve this problem. In the past, i posted the problem in the forum linked "http://www.bulletphysics.org/Bullet/php ... f=9&t=4545"

my codes:
//construct the hinge joint:
btTransform frameInA, frameInB;
frameInA = btTransform::getIdentity();
frameInA.setOrigin(btVector3(btScalar(-0.2f), btScalar(0.), btScalar(0.05)));
frameInB = btTransform::getIdentity();
frameInB.setOrigin(btVector3(btScalar(0.1f), btScalar(0.), btScalar(-0.05)));
btGeneric6DofConstraint* pHinge3 = new btGeneric6DofConstraint(*pBodyC, *pBodyD, frameInA, frameInB, true);

pHinge3->setLinearLowerLimit(btVector3(0., 0., 0.));
pHinge3->setLinearUpperLimit(btVector3(0., 0., 0.));
pHinge3->setAngularLowerLimit(btVector3(0.f,0., 1));
pHinge3->setAngularUpperLimit(btVector3(0.f,0., 0));

pHinge3->getRotationalLimitMotor(1)->m_ERP=1.0;//whether it is similar as ode's erp
m_dynamicsWorld->addConstraint(pHinge3, true);
pHinge3->setDbgDrawSize(btScalar(5.f));

//Add the torque on the crank(pbodyD):
btVector3 m_fT(0.0,0.0,15.0);
pBodyD->applyTorque(m_fT);

//stepsimulation:
m_dynamicsWorld->stepSimulation(0.0005);

//results:
see my uploaded figure

Any body can help me!
thanks very much!

foster

[Erwin Coumans]

Can you reproduce this using the latest Bullet trunk (or at least SVN revision 1871, download zipfile from http://code.google.com/p/bullet/downloads/list) ?

If not, please modify the Bullet/Demos/ConstraintDemo/ConstraintDemo.cpp with a reproduction case.

Thanks a lot,
Erwin