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separate spinning friction (torsional friction around contact normal) from

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rolling friction (orthogonal to contact normal)
This commit is contained in:
Erwin Coumans
2016-09-16 00:04:33 +01:00
parent 4d6a95017e
commit 1d88cf71e4
11 changed files with 67 additions and 9 deletions
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1
data/r2d2.urdf
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@@ -388,6 +388,7 @@
<child link="head"/>
<axis xyz="0 0 1"/>
<origin xyz="0 0 0.3"/>
<limit effort="1000.0" lower="-0.38" upper="0" velocity="0.5"/>
</joint>
<link name="box">

4
examples/Importers/ImportURDFDemo/URDF2Bullet.cpp
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@@ -410,6 +410,10 @@ void ConvertURDF2BulletInternal(
{
col->setRollingFriction(contactInfo.m_rollingFriction);
}
if ((contactInfo.m_flags & URDF_CONTACT_HAS_SPINNING_FRICTION)!=0)
{
col->setSpinningFriction(contactInfo.m_spinningFriction);
}
if ((contactInfo.m_flags & URDF_CONTACT_HAS_STIFFNESS_DAMPING)!=0)
{
col->setContactStiffnessAndDamping(contactInfo.m_contactStiffness,contactInfo.m_contactDamping);

6
examples/Importers/ImportURDFDemo/URDFJointTypes.h
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@@ -16,17 +16,20 @@ enum UrdfJointTypes
enum URDF_LinkContactFlags
{
URDF_CONTACT_HAS_LATERAL_FRICTION=1,
URDF_CONTACT_HAS_ROLLING_FRICTION=2,
URDF_CONTACT_HAS_INERTIA_SCALING=2,
URDF_CONTACT_HAS_CONTACT_CFM=4,
URDF_CONTACT_HAS_CONTACT_ERP=8,
URDF_CONTACT_HAS_STIFFNESS_DAMPING=16,
URDF_CONTACT_HAS_ROLLING_FRICTION=32,
URDF_CONTACT_HAS_SPINNING_FRICTION=64,
};
struct URDFLinkContactInfo
{
btScalar m_lateralFriction;
btScalar m_rollingFriction;
btScalar m_spinningFriction;
btScalar m_inertiaScaling;
btScalar m_contactCfm;
btScalar m_contactErp;
@@ -38,6 +41,7 @@ struct URDFLinkContactInfo
URDFLinkContactInfo()
:m_lateralFriction(0.5),
m_rollingFriction(0),
m_spinningFriction(0),
m_inertiaScaling(1),
m_contactCfm(0),
m_contactErp(0),

23
examples/Importers/ImportURDFDemo/UrdfParser.cpp
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@@ -672,7 +672,28 @@ bool UrdfParser::parseLink(UrdfModel& model, UrdfLink& link, TiXmlElement *confi
}
}
}
{
TiXmlElement *spinning_xml = ci->FirstChildElement("spinning_friction");
if (spinning_xml)
{
if (m_parseSDF)
{
link.m_contactInfo.m_spinningFriction = urdfLexicalCast<double>(spinning_xml->GetText());
link.m_contactInfo.m_flags |= URDF_CONTACT_HAS_SPINNING_FRICTION;
} else
{
if (!spinning_xml->Attribute("value"))
{
logger->reportError("Link/contact: spinning friction element must have value attribute");
return false;
}
link.m_contactInfo.m_spinningFriction = urdfLexicalCast<double>(spinning_xml->Attribute("value"));
link.m_contactInfo.m_flags |= URDF_CONTACT_HAS_SPINNING_FRICTION;
}
}
}
{
TiXmlElement *stiffness_xml = ci->FirstChildElement("stiffness");

1
src/BulletCollision/CollisionDispatch/btCollisionObject.cpp
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@@ -33,6 +33,7 @@ btCollisionObject::btCollisionObject()
m_friction(btScalar(0.5)),
m_restitution(btScalar(0.)),
m_rollingFriction(0.0f),
m_spinningFriction(0.f),
m_contactDamping(.1),
m_contactStiffness(1e4),
m_internalType(CO_COLLISION_OBJECT),

13
src/BulletCollision/CollisionDispatch/btCollisionObject.h
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@@ -85,7 +85,8 @@ protected:
btScalar m_friction;
btScalar m_restitution;
btScalar m_rollingFriction;
btScalar m_rollingFriction;//torsional friction orthogonal to contact normal (useful to stop spheres rolling forever)
btScalar m_spinningFriction; // torsional friction around the contact normal (useful for grasping)
btScalar m_contactDamping;
btScalar m_contactStiffness;
@@ -323,7 +324,15 @@ public:
{
return m_rollingFriction;
}
void setSpinningFriction(btScalar frict)
{
m_updateRevision++;
m_spinningFriction = frict;
}
btScalar getSpinningFriction() const
{
return m_spinningFriction;
}
void setContactStiffnessAndDamping(btScalar stiffness, btScalar damping)
{
m_updateRevision++;

12
src/BulletCollision/CollisionDispatch/btManifoldResult.cpp
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@@ -24,7 +24,6 @@ ContactAddedCallback gContactAddedCallback=0;
///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
btScalar btManifoldResult::calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
btScalar friction = body0->getRollingFriction() * body1->getFriction() + body1->getRollingFriction() * body0->getFriction();
@@ -38,6 +37,17 @@ btScalar btManifoldResult::calculateCombinedRollingFriction(const btCollisionObj
}
btScalar btManifoldResult::calculateCombinedSpinningFriction(const btCollisionObject* body0,const btCollisionObject* body1)
{
btScalar friction = body0->getSpinningFriction() * body1->getFriction() + body1->getSpinningFriction() * body0->getFriction();
const btScalar MAX_FRICTION = btScalar(10.);
if (friction < -MAX_FRICTION)
friction = -MAX_FRICTION;
if (friction > MAX_FRICTION)
friction = MAX_FRICTION;
return friction;
}
///User can override this material combiner by implementing gContactAddedCallback and setting body0->m_collisionFlags |= btCollisionObject::customMaterialCallback;
btScalar btManifoldResult::calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1)

3
src/BulletCollision/CollisionDispatch/btManifoldResult.h
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@@ -146,7 +146,8 @@ public:
static btScalar calculateCombinedRestitution(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedRollingFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactDamping(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedSpinningFriction(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactDamping(const btCollisionObject* body0,const btCollisionObject* body1);
static btScalar calculateCombinedContactStiffness(const btCollisionObject* body0,const btCollisionObject* body1);
};

8
src/BulletCollision/NarrowPhaseCollision/btManifoldPoint.h
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@@ -72,7 +72,8 @@ class btManifoldPoint
m_distance1( distance ),
m_combinedFriction(btScalar(0.)),
m_combinedRollingFriction(btScalar(0.)),
m_combinedRestitution(btScalar(0.)),
m_combinedSpinningFriction(btScalar(0.)),
m_combinedRestitution(btScalar(0.)),
m_userPersistentData(0),
m_contactPointFlags(0),
m_appliedImpulse(0.f),
@@ -99,8 +100,9 @@ class btManifoldPoint
btScalar m_distance1;
btScalar m_combinedFriction;
btScalar m_combinedRollingFriction;
btScalar m_combinedRestitution;
btScalar m_combinedRollingFriction;//torsional friction orthogonal to contact normal, useful to make spheres stop rolling forever
btScalar m_combinedSpinningFriction;//torsional friction around contact normal, useful for grasping objects
btScalar m_combinedRestitution;
//BP mod, store contact triangles.
int m_partId0;

2
src/BulletDynamics/Dynamics/btRigidBody.cpp
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@@ -79,6 +79,8 @@ void btRigidBody::setupRigidBody(const btRigidBody::btRigidBodyConstructionInfo&
//moved to btCollisionObject
m_friction = constructionInfo.m_friction;
m_rollingFriction = constructionInfo.m_rollingFriction;
m_spinningFriction = constructionInfo.m_spinningFriction;
m_restitution = constructionInfo.m_restitution;
setCollisionShape( constructionInfo.m_collisionShape );

3
src/BulletDynamics/Dynamics/btRigidBody.h
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@@ -135,6 +135,8 @@ public:
///the m_rollingFriction prevents rounded shapes, such as spheres, cylinders and capsules from rolling forever.
///See Bullet/Demos/RollingFrictionDemo for usage
btScalar m_rollingFriction;
btScalar m_spinningFriction;//torsional friction around contact normal
///best simulation results using zero restitution.
btScalar m_restitution;
@@ -158,6 +160,7 @@ public:
m_angularDamping(btScalar(0.)),
m_friction(btScalar(0.5)),
m_rollingFriction(btScalar(0)),
m_spinningFriction(btScalar(0)),
m_restitution(btScalar(0.)),
m_linearSleepingThreshold(btScalar(0.8)),
m_angularSleepingThreshold(btScalar(1.f)),