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fix rotational friction between btMultiBody and btRigidBody

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This commit is contained in:
Erwin Coumans
2019-07-24 22:07:16 -07:00
parent e96f068220
commit 3eedb2a6f2
3 changed files with 60 additions and 4 deletions
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15
examples/pybullet/examples/rotationalFriction.py Normal file
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@@ -0,0 +1,15 @@
import time
import pybullet as p
import pybullet_data as pd
useMaximalCoordinatesA = True
useMaximalCoordinatesB = True
p.connect(p.GUI)
p.setAdditionalSearchPath(pd.getDataPath())
cube=p.loadURDF("cube_rotate.urdf",useMaximalCoordinates=useMaximalCoordinatesA)
p.loadURDF("sphere2.urdf",[0,0,2],useMaximalCoordinates=useMaximalCoordinatesB)
p.setGravity(0,0,-10)
p.setJointMotorControl2(cube,0,p.VELOCITY_CONTROL,targetVelocity=1, force=100)
while (1):
p.stepSimulation()
time.sleep(1./240.)

41
examples/pybullet/gym/pybullet_data/cube_rotate.urdf Normal file
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@@ -0,0 +1,41 @@
<?xml version="1.0" ?>
<robot name="cube">
<link name="world"/>
<link name="baseLink">
<contact>
<lateral_friction value="1.0"/>
<rolling_friction value="0.0"/>
<contact_cfm value="0.0"/>
<contact_erp value="1.0"/>
</contact>
<inertial>
<origin rpy="0 0 0" xyz="0 0 0"/>
<mass value="1.0"/>
<inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
</inertial>
<visual>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<mesh filename="cube.obj" scale="1 1 1"/>
</geometry>
<material name="white">
<color rgba="1 1 1 1"/>
</material>
</visual>
<collision>
<origin rpy="0 0 0" xyz="0 0 0"/>
<geometry>
<box size="1 1 1"/>
</geometry>
</collision>
</link>
<joint name="joint_baseLink_world" type="continuous">
<parent link="world"/>
<child link="baseLink"/>
<dynamics damping="1.0" friction="0.0001"/>
<origin xyz="0 0 0"/>
<axis xyz="0 0 1"/>
</joint>
</robot>

8
src/BulletDynamics/Featherstone/btMultiBodyConstraintSolver.cpp
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@@ -944,13 +944,13 @@ void btMultiBodyConstraintSolver::setupMultiBodyTorsionalFrictionConstraint(btMu
btScalar* delta = &m_data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacAindex];
multiBodyA->calcAccelerationDeltasMultiDof(&m_data.m_jacobians[solverConstraint.m_jacAindex], delta, m_data.scratch_r, m_data.scratch_v);
btVector3 torqueAxis0 = -constraintNormal;
btVector3 torqueAxis0 = constraintNormal;
solverConstraint.m_relpos1CrossNormal = torqueAxis0;
solverConstraint.m_contactNormal1 = btVector3(0, 0, 0);
}
else
{
btVector3 torqueAxis0 = -constraintNormal;
btVector3 torqueAxis0 = constraintNormal;
solverConstraint.m_relpos1CrossNormal = torqueAxis0;
solverConstraint.m_contactNormal1 = btVector3(0, 0, 0);
solverConstraint.m_angularComponentA = rb0 ? rb0->getInvInertiaTensorWorld() * torqueAxis0 * rb0->getAngularFactor() : btVector3(0, 0, 0);
@@ -986,13 +986,13 @@ void btMultiBodyConstraintSolver::setupMultiBodyTorsionalFrictionConstraint(btMu
multiBodyB->fillConstraintJacobianMultiDof(solverConstraint.m_linkB, cp.getPositionWorldOnB(), -constraintNormal, btVector3(0, 0, 0), &m_data.m_jacobians[solverConstraint.m_jacBindex], m_data.scratch_r, m_data.scratch_v, m_data.scratch_m);
multiBodyB->calcAccelerationDeltasMultiDof(&m_data.m_jacobians[solverConstraint.m_jacBindex], &m_data.m_deltaVelocitiesUnitImpulse[solverConstraint.m_jacBindex], m_data.scratch_r, m_data.scratch_v);
btVector3 torqueAxis1 = constraintNormal;
btVector3 torqueAxis1 = -constraintNormal;
solverConstraint.m_relpos2CrossNormal = torqueAxis1;
solverConstraint.m_contactNormal2 = -btVector3(0, 0, 0);
}
else
{
btVector3 torqueAxis1 = constraintNormal;
btVector3 torqueAxis1 = -constraintNormal;
solverConstraint.m_relpos2CrossNormal = torqueAxis1;
solverConstraint.m_contactNormal2 = -btVector3(0, 0, 0);