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implement joint reaction forces for mobilizer motor/limit, by passing the constraint forces as 'external forces' and going through the Articulated Body Algorithm

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minor refactor for forwardKinematics, store the cached world transform in each btMultiBody::link
This commit is contained in:
erwin coumans
2015-06-19 15:51:24 -07:00
parent 89edc40d61
commit 6e9eb13235
9 changed files with 178 additions and 91 deletions
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45
src/BulletDynamics/Featherstone/btMultiBodyJointMotor.cpp
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@@ -22,11 +22,11 @@ subject to the following restrictions:
btMultiBodyJointMotor::btMultiBodyJointMotor(btMultiBody* body, int link, btScalar desiredVelocity, btScalar maxMotorImpulse)
:btMultiBodyConstraint(body,body,link,link,1,true),
:btMultiBodyConstraint(body,body,link,body->getLink(link).m_parent,1,true),
m_desiredVelocity(desiredVelocity)
{
int parent = body->getLink(link).m_parent;
m_maxAppliedImpulse = maxMotorImpulse;
// the data.m_jacobians never change, so may as well
// initialize them here
@@ -51,7 +51,7 @@ void btMultiBodyJointMotor::finalizeMultiDof()
btMultiBodyJointMotor::btMultiBodyJointMotor(btMultiBody* body, int link, int linkDoF, btScalar desiredVelocity, btScalar maxMotorImpulse)
//:btMultiBodyConstraint(body,0,link,-1,1,true),
:btMultiBodyConstraint(body,body,link,link,1,true),
:btMultiBodyConstraint(body,body,link,body->getLink(link).m_parent,1,true),
m_desiredVelocity(desiredVelocity)
{
btAssert(linkDoF < body->getLink(link).m_dofCount);
@@ -98,7 +98,7 @@ void btMultiBodyJointMotor::createConstraintRows(btMultiBodyConstraintArray& con
{
// only positions need to be updated -- data.m_jacobians and force
// directions were set in the ctor and never change.
if (m_numDofsFinalized != m_jacSizeBoth)
{
finalizeMultiDof();
@@ -117,7 +117,42 @@ void btMultiBodyJointMotor::createConstraintRows(btMultiBodyConstraintArray& con
fillMultiBodyConstraint(constraintRow,data,jacobianA(row),jacobianB(row),dummy,dummy,dummy,posError,infoGlobal,-m_maxAppliedImpulse,m_maxAppliedImpulse,1,false,m_desiredVelocity);
constraintRow.m_useJointForce = true;
if (m_bodyA->isMultiDof())
{
constraintRow.m_useJointForce = false;
//expect either prismatic or revolute joint type for now
btAssert((m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::eRevolute)||(m_bodyA->getLink(m_linkA).m_jointType == btMultibodyLink::ePrismatic));
switch (m_bodyA->getLink(m_linkA).m_jointType)
{
case btMultibodyLink::eRevolute:
{
constraintRow.m_contactNormal1.setZero();
constraintRow.m_contactNormal2.setZero();
btVector3 revoluteAxisInWorld = quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(),m_bodyA->getLink(m_linkA).m_axes[0].m_topVec);
constraintRow.m_relpos1CrossNormal=revoluteAxisInWorld;
constraintRow.m_relpos2CrossNormal=-revoluteAxisInWorld;
break;
}
case btMultibodyLink::ePrismatic:
{
btVector3 prismaticAxisInWorld = quatRotate(m_bodyA->getLink(m_linkA).m_cachedWorldTransform.getRotation(),m_bodyA->getLink(m_linkA).m_axes[0].m_bottomVec);
constraintRow.m_contactNormal1=prismaticAxisInWorld;
constraintRow.m_contactNormal2=-prismaticAxisInWorld;
constraintRow.m_relpos1CrossNormal.setZero();
constraintRow.m_relpos2CrossNormal.setZero();
break;
}
default:
{
btAssert(0);
}
};
}
}
}