Rigidfication of an object with SofaCUDA

[jemmyjiang15]

Hi,

I'm trying to get CUDA to work with a simulation that I'm working on. It works fine without CUDA but I'm curious as to whether changing to CUDA would improve the simulation performance or not.

It involves a soft finray finger which is imported as a MeshStringForceField using the following function:

def fingerNode(parent, name="Finger", scale: list = [1, 1, 1],
                translation: list = [0, 0, 0], rotation: list = [0, 0, 0], stiffness: float = 1200,
                damping: float = 0, totalMass:float = 3.14e-3):
    finger = parent.addChild(name)
    finger.addObject('EulerImplicitSolver', name='odeSolver')
    finger.addObject('CGLinearSolver', iterations="25", tolerance=1e-9, threshold=1e-9)

    finger.loader = finger.addObject('MeshGmshLoader', name='loader', filename='Data/t20.msh', 
                                        rotation=rotation, translation=translation, scale3d=scale)
    finger.addObject('MechanicalObject', name='dofs', template='CudaVec3f', src="@loader")
    finger.container = finger.addObject('TetrahedronSetTopologyContainer', src=finger.loader.getLinkPath(), name='container')
    
    finger.addObject('UniformMass', totalMass=totalMass, name='mass', topology='@container')
    finger.addObject('MeshSpringForceField', name='Springs', template='CudaVec3f',tetrasStiffness=stiffness, tetrasDamping=damping, topology='@container')

    return finger

This function is called by an ActuatedFinger node, the same class that is used in the SoftFingerDesign example, and replaces the elasticBody() function, which would've used FEM.

The Rigidify() function imported from stlib3.physics.mixedmaterial is then used to fix the soft finger to the gripper holder:

# Rigidify the finger nodes in the ROI. Create a Rigidified object and set up a spring force
        # field to constrain the nodes to stay in the rest shape
        rigidifiedStruct = Rigidify(self, self.elasticMaterial, groupIndices=indices, frames=frame,
                                    name="RigidifiedStructure")

        servoArm = arm.ServoMotor.Articulation.ServoWheel.ServoArm
        servoArm.addChild(rigidifiedStruct.RigidParts)
        servoArm.RigidParts.addObject('RigidRigidMapping', index=0, input=servoArm.dofs.getLinkPath())

The problem arises when the Rigidify() function is called, which produces the following error:

CUDA: 1 device(s) found.
CUDA:  0 : "NVIDIA RTX A2000 8GB Laptop GPU", 7208/8191 MB, 160 cores at 1.177 GHz, revision 8.6, timeout enabled
CUDA: Using device 0 : "NVIDIA RTX A2000 8GB Laptop GPU"
[INFO]    [PluginManager] Loaded plugin: C:/Users/JIA/Documents/Defrost/bin/SofaCUDA.dll
CUDA SpringForceField: 2367 springs, 497 attached points, max 21 springs per point.
TEST HERE : [[0.]]
[ERROR]   [SofaPython3::SceneLoader] Unable to completely load the scene from file '3_gripper_simulation.py'.
Python exception:
  ValueError: Object type SubsetMultiMapping<Vec3d,Vec3d> was not created
The object is in the factory but cannot be created.
Requested template : Vec3,Vec3
Used template      : Vec3d,Vec3d
Reason(s)          : The 'output' data attribute does not contain a valid path to one or more mechanical states of type 'Vec3d'.
Also tried to create the object with the template 'CudaRigid3f,CudaRigid3f' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'CudaRigid3f'.
Also tried to create the object with the template 'CudaRigid3f,CudaVec3f' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'CudaRigid3f'.
Also tried to create the object with the template 'CudaVec1f,CudaVec1f' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'CudaVec1f'.
Also tried to create the object with the template 'CudaVec3f,CudaVec3f' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'CudaVec3f'.
Also tried to create the object with the template 'Rigid3d,Rigid3d' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'Rigid3d'.
Also tried to create the object with the template 'Rigid3d,Vec3d' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'Rigid3d'.
Also tried to create the object with the template 'Vec1d,Vec1d' but failed for the following reason(s):
    1. The 'input' data attribute does not contain a valid path to one or more mechanical states of type 'Vec1d'.



At:
  C:\Users/JIA/Documents/Defrost/plugins/STLIB/lib/python3/site-packages\stlib3\physics\mixedmaterial\rigidification.py(126): Rigidify
  C:\Users\JIA\Documents\GitHub\Physics-Sim\SOFA\Rigid\actuated_finger_array.py(55): init
  C:\Users\JIA\Documents\Defrost\plugins\SofaPython3\lib\python3\site-packages\Sofa\prefab.py(123): __init__
  C:\Users\JIA\Documents\GitHub\Physics-Sim\SOFA\Rigid\actuated_finger_array.py(25): __init__
  C:\Users\JIA\Documents\GitHub\Physics-Sim\SOFA\Rigid\3_gripper_simulation.py(39): createScene

Is it because Rigidify cannot be used with SofaCUDA at the moment, or am I making a mistake elsewhere? Happy to send more code should it be necessary.

Thanks,
Jemmy

[alxbilger]

Hi,

you are perfectly right. The function Rigidify has not been designed to support other templates than Vec3. I can make the change to introduce this support in STLIB. In the meantime, could you just try to replace Vec3 by CudaVec3f in the content of the Rigidify function? You need to replace template="Vec3" by template="CudaVec3f" and template="Vec3,Vec3" by template="CudaVec3f,CudaVec3f". Let me know if it works.

[jemmyjiang15]

Hi Alex,

this does seem to work. However, there appears to be another problem with this section of code in the simulation file:

# Temporary addition to have the system correctly built in SOFA
# Will no longer be required in SOFA v22.12
scene.Simulation.addObject('MechanicalMatrixMapper',
                           name="deformableAndFreeCenterCoupling1",
                           template='Vec1,Vec3',
                           object1=actuatedFingerLeft.ActuatedArmLeft.ServoMotor.Articulation.dofs.getLinkPath(),
                           object2=actuatedFingerLeft.RigidifiedStructure.DeformableParts.dofs.getLinkPath(),
                           nodeToParse=actuatedFingerLeft.RigidifiedStructure.DeformableParts.Finger.getLinkPath())

And it is causing it to segfault:

[WARNING] [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] Link update failed for object2 = @/Modelling/ActuatedFingerLeft/RigidifiedStructure/DeformableParts/dofs
[ERROR]   [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] MechanicalState #2 (object2): No compatible MechanicalState found in the current context. This may be because there is no MechanicalState in the local context, or because the type is not compatible.
[ERROR]   [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)]  failed to initialized -> missing/wrong link object1 or object2
[ERROR]   [UniformMass(mass)] TopologyData: indices already has a TopologyDataHandler. createTopologyHandler should only be called once at init of the TopologyData.
[WARNING] [UniformMass(mass)] totalMass value overriding the value of the attribute vertexMass.
vertexMass = totalMass / nb_dofs.
To remove this warning you need to set either totalMass or vertexMass data field, but not both.
CUDA SpringForceField: 2367 springs, 497 attached points, max 21 springs per point.

########## SIG 11 - SIGSEGV: segfault ##########
  sofa::helper::BackTrace::dump
  sofa::helper::BackTrace::sig
  seh_filter_exe
  seh_filter_exe
  _C_specific_handler
  _chkstk
  RtlRaiseException
  KiUserExceptionDispatcher
  sofa::component::mapping::mappedmatrix::MechanicalMatrixMapper<sofa::defaulttype::StdVectorTypes<sofa::type::Vec<3,double>,sofa::type::Vec<3,double>,double>,sofa::defaulttype::StdRigidTypes<3,double> >::bwdInit
  sofa::simulation::InitVisitor::processNodeBottomUp
  sofa::simulation::graph::DAGNode::executeVisitorBottomUp
  sofa::simulation::graph::DAGNode::doExecuteVisitor
  sofa::simulation::Node::executeVisitor
  sofa::simulation::Simulation::initNode
  sofa::simulation::Simulation::init
  sofa::simulation::Simulation::init
  sofa::simulation::Simulation::init
  BaseThreadInitThunk
  RtlUserThreadStart

I have tried changing the template to template='Vec1,CudaVec3f' which produces the same segfault with these new error messages:

[WARNING] [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] Link update failed for object1 = @/Modelling/ActuatedFingerLeft/ActuatedArmLeft/ServoMotor/Articulation/dofs
[WARNING] [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] Link update failed for object2 = @/Modelling/ActuatedFingerLeft/RigidifiedStructure/DeformableParts/dofs
[ERROR]   [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] MechanicalState #1 (object1): No compatible MechanicalState found in the current context. This may be because there is no MechanicalState in the local context, or because the type is not compatible.
[ERROR]   [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)] MechanicalState #2 (object2): No compatible MechanicalState found in the current context. This may be because there is no MechanicalState in the local context, or because the type is not compatible.
[ERROR]   [MechanicalMatrixMapper(deformableAndFreeCenterCoupling1)]  failed to initialized -> missing/wrong link object1 or object2

Finally, I've tried to remove that section altogether as it was stated that v22.12 would not require this bit of code. Although the objects and scene would load successfully, it also produced an error upon clicking 'Animate', where SOFA would crash and print this segfault message:

[WARNING] [SparseLDLSolver(LinearSolver)] Invalid Linear System to solve. Please insure that there is enough constraints (not rank deficient).

########## SIG 11 - SIGSEGV: segfault ##########
  sofa::helper::BackTrace::dump
  sofa::helper::BackTrace::sig
  seh_filter_exe
  seh_filter_exe
  _C_specific_handler
  _chkstk
  RtlRaiseException
  KiUserExceptionDispatcher
  sofa::component::linearsolver::direct::SparseLDLSolver<sofa::linearalgebra::CompressedRowSparseMatrix<double,sofa::type::vector<double,sofa::type::CPUMemoryManager<double> >,sofa::type::vector<unsigned int,sofa::type::CPUMemoryManager<unsigned int> > >,so
  sofa::component::linearsolver::MatrixLinearSolver<sofa::component::linearsolver::GraphScatteredMatrix,sofa::component::linearsolver::GraphScatteredVector,sofa::component::linearsolver::NoThreadManager>::addJMInvJt
  sofa::component::linearsolver::MatrixLinearSolver<sofa::linearalgebra::CompressedRowSparseMatrix<double,sofa::type::vector<double,sofa::type::CPUMemoryManager<double> >,sofa::type::vector<unsigned int,sofa::type::CPUMemoryManager<unsigned int> > >,sofa::l
  sofa::component::constraint::lagrangian::correction::GenericConstraintCorrection::addComplianceInConstraintSpace
  sofa::component::constraint::lagrangian::solver::GenericConstraintSolver::sequentialBuildSystem_matrixAssembly
  sofa::component::constraint::lagrangian::solver::GenericConstraintSolver::buildSystem_matrixAssembly
  sofa::component::constraint::lagrangian::solver::GenericConstraintSolver::buildSystem
  sofa::core::behavior::ConstraintSolver::solveConstraint
  sofa::component::animationloop::FreeMotionAnimationLoop::step
  sofa::simulation::Simulation::animate
  sofa::gui::qt::RealGUI::step
  QMetaObject::activate
  QTimer::timerEvent
  QObject::event
  QApplicationPrivate::notify_helper
  QApplication::notify
  QCoreApplication::notifyInternal2
  QEventDispatcherWin32::event
  QApplicationPrivate::notify_helper
  QApplication::notify
  QCoreApplication::notifyInternal2
  QCoreApplicationPrivate::sendPostedEvents
  qt_plugin_query_metadata
  QEventDispatcherWin32::processEvents
  CallWindowProcW
  DispatchMessageW
  QEventDispatcherWin32::processEvents
  qt_plugin_query_metadata
  QEventLoop::exec
  QCoreApplication::exec
  sofa::gui::qt::RealGUI::mainLoop
  sofa::gui::common::GUIManager::MainLoop
  sofa::gui::common::GUIManager::MainLoop
  sofa::gui::common::GUIManager::MainLoop
  BaseThreadInitThunk
  RtlUserThreadStart

[alxbilger]

Your approach was good.

The MechanicalMatrixMapper is deprecated but not in 22.12. It is deprecated in the master branch, and starting 23.06 (which is not yet available). I am afraid that you need it if you are with 22.12 and earlier.

The crash happening if you remove MechanicalMatrixMapper is in SparseLDLSolver. But without more information, I cannot really say why it crashes (and how to fix it). If you are on 22.12, it's probably because you really need the MechanicalMatrixMapper.

MechanicalMatrixMapper is not available for cuda types...

The best strategy would probably be to use the master branch of SOFA where you don't need the MechanicalMatrixMapper... By the way, I think they have been removed in STLIB (in its master branch).