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Add secondary friction coefficient parameter #1424

Merged
merged 11 commits into from
Nov 21, 2019
70 changes: 61 additions & 9 deletions dart/constraint/ContactConstraint.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -114,14 +114,24 @@ ContactConstraint::ContactConstraint(
//----------------------------------------------
// TODO(JS): Assume the frictional coefficient can be changed during
// simulation steps.
// Update mFrictionalCoff
const double frictionCoeffA = computeFrictionCoefficient(shapeNodeA);
const double frictionCoeffB = computeFrictionCoefficient(shapeNodeB);
// Update mFrictionCoeff
const double primaryFrictionCoeffA =
computePrimaryFrictionCoefficient(shapeNodeA);
const double primaryFrictionCoeffB =
computePrimaryFrictionCoefficient(shapeNodeB);
const double secondaryFrictionCoeffA =
computeSecondaryFrictionCoefficient(shapeNodeA);
const double secondaryFrictionCoeffB =
computeSecondaryFrictionCoefficient(shapeNodeB);

// TODO(JS): Consider providing various ways of the combined friction or
// allowing to override this method by a custom method
mFrictionCoeff = std::min(frictionCoeffA, frictionCoeffB);
if (mFrictionCoeff > DART_FRICTION_COEFF_THRESHOLD)
mPrimaryFrictionCoeff =
std::min(primaryFrictionCoeffA, primaryFrictionCoeffB);
mSecondaryFrictionCoeff =
std::min(secondaryFrictionCoeffA, secondaryFrictionCoeffB);
if (mPrimaryFrictionCoeff > DART_FRICTION_COEFF_THRESHOLD ||
mSecondaryFrictionCoeff > DART_FRICTION_COEFF_THRESHOLD)
{
mIsFrictionOn = true;

Expand Down Expand Up @@ -387,13 +397,13 @@ void ContactConstraint::getInformation(ConstraintInfo* info)
assert(info->findex[0] == -1);

// Upper and lower bounds of tangential direction-1 impulsive force
info->lo[1] = -mFrictionCoeff;
info->hi[1] = mFrictionCoeff;
info->lo[1] = -mPrimaryFrictionCoeff;
info->hi[1] = mPrimaryFrictionCoeff;
info->findex[1] = 0;

// Upper and lower bounds of tangential direction-2 impulsive force
info->lo[2] = -mFrictionCoeff;
info->hi[2] = mFrictionCoeff;
info->lo[2] = -mSecondaryFrictionCoeff;
info->hi[2] = mSecondaryFrictionCoeff;
info->findex[2] = 0;

//------------------------------------------------------------------------
Expand Down Expand Up @@ -702,6 +712,48 @@ double ContactConstraint::computeFrictionCoefficient(
return dynamicAspect->getFrictionCoeff();
}

//==============================================================================
double ContactConstraint::computePrimaryFrictionCoefficient(
const dynamics::ShapeNode* shapeNode)
{
assert(shapeNode);

auto dynamicAspect = shapeNode->getDynamicsAspect();

if (dynamicAspect == nullptr)
{
dtwarn << "[ContactConstraint] Attempt to extract "
<< "primary friction coefficient "
<< "from a ShapeNode that doesn't have DynamicAspect. The default "
<< "value (" << DART_DEFAULT_FRICTION_COEFF << ") will be used "
<< "instead.\n";
return DART_DEFAULT_FRICTION_COEFF;
}

return dynamicAspect->getPrimaryFrictionCoeff();
}

//==============================================================================
double ContactConstraint::computeSecondaryFrictionCoefficient(
const dynamics::ShapeNode* shapeNode)
{
assert(shapeNode);

auto dynamicAspect = shapeNode->getDynamicsAspect();

if (dynamicAspect == nullptr)
{
dtwarn << "[ContactConstraint] Attempt to extract "
<< "secondary friction coefficient "
<< "from a ShapeNode that doesn't have DynamicAspect. The default "
<< "value (" << DART_DEFAULT_FRICTION_COEFF << ") will be used "
<< "instead.\n";
return DART_DEFAULT_FRICTION_COEFF;
}

return dynamicAspect->getSecondaryFrictionCoeff();
}

//==============================================================================
double ContactConstraint::computeRestitutionCoefficient(
const dynamics::ShapeNode* shapeNode)
Expand Down
11 changes: 9 additions & 2 deletions dart/constraint/ContactConstraint.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,10 @@ class ContactConstraint : public ConstraintBase

static double computeFrictionCoefficient(
const dynamics::ShapeNode* shapeNode);
static double computePrimaryFrictionCoefficient(
const dynamics::ShapeNode* shapeNode);
static double computeSecondaryFrictionCoefficient(
const dynamics::ShapeNode* shapeNode);
static double computeRestitutionCoefficient(
const dynamics::ShapeNode* shapeNode);

Expand Down Expand Up @@ -173,8 +177,11 @@ class ContactConstraint : public ConstraintBase
/// First frictional direction
Eigen::Vector3d mFirstFrictionalDirection;

/// Coefficient of Friction
double mFrictionCoeff;
/// Primary Coefficient of Friction
double mPrimaryFrictionCoeff;

/// Primary Coefficient of Friction
double mSecondaryFrictionCoeff;

/// Coefficient of restitution
double mRestitutionCoeff;
Expand Down
29 changes: 28 additions & 1 deletion dart/dynamics/ShapeFrame.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,21 @@ CollisionAspectProperties::CollisionAspectProperties(const bool collidable)
//==============================================================================
DynamicsAspectProperties::DynamicsAspectProperties(
const double frictionCoeff, const double restitutionCoeff)
: mFrictionCoeff(frictionCoeff), mRestitutionCoeff(restitutionCoeff)
: mPrimaryFrictionCoeff(frictionCoeff),
mRestitutionCoeff(restitutionCoeff),
mSecondaryFrictionCoeff(frictionCoeff)
{
// Do nothing
}

//==============================================================================
DynamicsAspectProperties::DynamicsAspectProperties(
const double primaryFrictionCoeff,
const double secondaryFrictionCoeff,
const double restitutionCoeff)
: mPrimaryFrictionCoeff(primaryFrictionCoeff),
mRestitutionCoeff(restitutionCoeff),
mSecondaryFrictionCoeff(secondaryFrictionCoeff)
{
// Do nothing
}
Expand Down Expand Up @@ -173,6 +187,19 @@ DynamicsAspect::DynamicsAspect(const PropertiesData& properties)
// Do nothing
}

void DynamicsAspect::setFrictionCoeff(const double& value)
{
mProperties.mPrimaryFrictionCoeff = value;
mProperties.mSecondaryFrictionCoeff = value;
}

double DynamicsAspect::getFrictionCoeff() const
{
return 0.5 * (
mProperties.mPrimaryFrictionCoeff +
mProperties.mSecondaryFrictionCoeff);
}

//==============================================================================
ShapeFrame::~ShapeFrame()
{
Expand Down
14 changes: 11 additions & 3 deletions dart/dynamics/ShapeFrame.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -143,9 +143,17 @@ class DynamicsAspect final : public common::AspectWithVersionedProperties<

DynamicsAspect(const PropertiesData& properties = PropertiesData());

DART_COMMON_SET_GET_ASPECT_PROPERTY(double, FrictionCoeff)
// void setFrictionCoeff(const double& value);
// const double& getFrictionCoeff() const;
/// Set both primary and secondary friction coefficients to the same value.
void setFrictionCoeff(const double& value);
/// Get average of primary and secondary friction coefficients.
double getFrictionCoeff() const;

DART_COMMON_SET_GET_ASPECT_PROPERTY(double, PrimaryFrictionCoeff)
// void setPrimaryFrictionCoeff(const double& value);
// const double& getPrimaryFrictionCoeff() const;
DART_COMMON_SET_GET_ASPECT_PROPERTY( double, SecondaryFrictionCoeff )
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// void setSecondaryFrictionCoeff(const double& value);
// const double& getSecondaryFrictionCoeff() const;
DART_COMMON_SET_GET_ASPECT_PROPERTY(double, RestitutionCoeff)
// void setRestitutionCoeff(const double& value);
// const double& getRestitutionCoeff() const;
Expand Down
15 changes: 12 additions & 3 deletions dart/dynamics/detail/ShapeFrameAspect.hpp
Original file line number Diff line number Diff line change
Expand Up @@ -88,16 +88,25 @@ struct CollisionAspectProperties

struct DynamicsAspectProperties
{
/// Coefficient of friction
double mFrictionCoeff;
/// Primary coefficient of friction
double mPrimaryFrictionCoeff;
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This breaks backward compatibility since we're changing the name of the public member variable. Could we keep the variable name and add custom functions (i.e., set/getPrimaryFrictionCoeff) to DynamicAspect instead of DART_COMMON_SET_GET_ASPECT_PROPERTY(double, PrimaryFrictionCoeff)?

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/// Coefficient of restitution
double mRestitutionCoeff;

/// Constructor
/// Secondary coefficient of friction
double mSecondaryFrictionCoeff;

/// Constructors
/// The frictionCoeff argument will be used for both primary and secondary friction
DynamicsAspectProperties(
const double frictionCoeff = 1.0, const double restitutionCoeff = 0.0);

DynamicsAspectProperties(
const double primaryFrictionCoeff,
const double secondaryFrictionCoeff,
const double restitutionCoeff);

/// Destructor
virtual ~DynamicsAspectProperties() = default;
};
Expand Down
43 changes: 37 additions & 6 deletions unittests/comprehensive/test_Friction.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -80,15 +80,46 @@ TEST(Friction, FrictionPerShapeNode)
skeleton1->setName("Skeleton2");

auto body1 = skeleton1->getRootBodyNode();
EXPECT_DOUBLE_EQ(
body1->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff(), 1.0);
// default friction values
EXPECT_DOUBLE_EQ(1.0,
body1->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
EXPECT_DOUBLE_EQ(1.0,
body1->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
EXPECT_DOUBLE_EQ(1.0,
body1->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());

auto body2 = skeleton2->getRootBodyNode();
EXPECT_DOUBLE_EQ(
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff(), 1.0);
// default friction values
EXPECT_DOUBLE_EQ(1.0,
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
EXPECT_DOUBLE_EQ(1.0,
body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
EXPECT_DOUBLE_EQ(1.0,
body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
// test setting primary friction
body2->getShapeNode(0)->getDynamicsAspect()->setPrimaryFrictionCoeff(0.5);
EXPECT_DOUBLE_EQ(0.75,
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
EXPECT_DOUBLE_EQ(0.5,
body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
EXPECT_DOUBLE_EQ(1.0,
body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
// test setting secondary friction
body2->getShapeNode(0)->getDynamicsAspect()->setSecondaryFrictionCoeff(0.25);
EXPECT_DOUBLE_EQ(0.375,
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
EXPECT_DOUBLE_EQ(0.5,
body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
EXPECT_DOUBLE_EQ(0.25,
body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());
// set all friction coeffs to 0.0
body2->getShapeNode(0)->getDynamicsAspect()->setFrictionCoeff(0.0);
EXPECT_DOUBLE_EQ(
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff(), 0.0);
EXPECT_DOUBLE_EQ(0.0,
body2->getShapeNode(0)->getDynamicsAspect()->getFrictionCoeff());
EXPECT_DOUBLE_EQ(0.0,
body2->getShapeNode(0)->getDynamicsAspect()->getPrimaryFrictionCoeff());
EXPECT_DOUBLE_EQ(0.0,
body2->getShapeNode(0)->getDynamicsAspect()->getSecondaryFrictionCoeff());

// Create a world and add the rigid body
auto world = simulation::World::create();
Expand Down