OpenSim::RollingOnSurfaceConstraint Class Reference

A class implementing a collection of rolling-without-slipping and non-penetration constraints on a surface. More...

#include <RollingOnSurfaceConstraint.h>

Inheritance diagram for OpenSim::RollingOnSurfaceConstraint:

Public Member Functions
	RollingOnSurfaceConstraint ()
	Default constructor.
	RollingOnSurfaceConstraint (const RollingOnSurfaceConstraint &aConstraint)
	Copy constructor.
virtual	~RollingOnSurfaceConstraint ()
	Destructor.
virtual Object *	copy () const
	Copy this body and return a pointer to the copy.
RollingOnSurfaceConstraint &	operator= (const RollingOnSurfaceConstraint &aConstraint)
	Assignment operator.
void	copyData (const RollingOnSurfaceConstraint &aConstraint)
	Copy data members from one RollingOnSurfaceConstraint to another.
virtual void	setup (Model &aModel)
	Perform some setup functions that happen after the object has been deserialized or copied.
void	setRollingBodyByName (std::string aBodyName)
	Following methods set attributes of the weld constraint.
void	setSurfaceBodyByName (std::string aBodyName)
void	setContactPointSurfaceBody (SimTK::Vec3 point)
virtual std::vector< bool >	unilateralConditionsSatisfied (SimTK::State &state)
virtual bool	getIsDisabled (const SimTK::State &state) const
	Get whether or not the RollingOnSurfaceConstraint is disabled.
virtual bool	setIsDisabled (SimTK::State &state, bool isDisabled)
	Set whether or not the RollingOnSurfaceConstraint is disabled.
bool	setIsDisabled (SimTK::State &state, bool isDisabled, std::vector< bool > shouldBeOn)
bool	setIsDisabledWithCachedUnilateralConditions (bool isDisabled, SimTK::State &state)
virtual void	calcConstraintForces (const SimTK::State &state, SimTK::Vector_< SimTK::SpatialVec > &bodyForcesInParent, SimTK::Vector &mobilityForces)
	Ask the RollingOnSurfaceConstraint for the forces it is imposing on the system Simbody multibody system must be realized to at least position Returns: the bodyForces on those bodies being constrained (constrainedBodies) a SpatialVec (6 components) describing resulting torque and force mobilityForces acting along constrained mobilities.
Protected Attributes
PropertyStr	_rollingBodyNameProp
	Specify the rolling body for this constraint.
std::string &	_rollingBodyName
PropertyStr	_surfaceBodyNameProp
	Specify the body containing the surface (plane) that the rolling body rolls on.
std::string &	_surfaceBodyName
PropertyDblVec3	_surfaceNormalProp
	Surface normal direction in the surface body.
SimTK::Vec3 &	_surfaceNormal
PropertyDbl	_surfaceHeightProp
	Surface height in the direction of the normal in the surface body.
double &	_surfaceHeight
PropertyDbl	_coulombFrictionCoefficientProp
	Coulomb friction coefficient for rolling on the surface.
double &	_coulombFrictionCoefficient
PropertyDbl	_surfaceContactRadiusProp
	A guess at the area of contact approximated by a circle of radius:.
double &	_surfaceContactRadius
Body *	_rollingBody
	First body is the rolling body.
Body *	_surfaceBody
	Second body describes the surface body.
std::vector < SimTK::ConstraintIndex >	_indices
	Get the indices of underlying constraints to access from Simbody.
std::vector< bool >	_cachedUnilateralConditions
	This cache acts a temporary hold for the constraint conditions when time has not changed.
Friends
class	SimbodyEngine

Detailed Description

A class implementing a collection of rolling-without-slipping and non-penetration constraints on a surface.

The underlying Constraints in Simbody are: PointInPlane to oppose penetration into the ground (unitlaterally) ConstantAngle about the normal to the enforce no spinning NoSlip1D along one axis of the plane NoSlip1D along the other axis

mu = Coulomb Friction Coeefficient

Each of these constraints have condition dependent on the reaction forces generate collectively: PointInPlane normal force (Fn) must be positive (in the direction of the normal) ConstantAngle the reaction torque cannnot exceed contactRadius*mu*Fn Both NoSlip conditions are treated together, the magnitude the combined reaction forces (in the plane) cannot exceed mu*Fn

Author:: Ajay Seth

Version:: 1.0

Constructor & Destructor Documentation

RollingOnSurfaceConstraint::RollingOnSurfaceConstraint ( )

Default constructor.

RollingOnSurfaceConstraint::RollingOnSurfaceConstraint ( const RollingOnSurfaceConstraint & aConstraint )

Copy constructor.

Parameters:

aConstraint

RollingOnSurfaceConstraint to be copied.

RollingOnSurfaceConstraint::~RollingOnSurfaceConstraint ( ) [virtual]

Destructor.

Member Function Documentation

void RollingOnSurfaceConstraint::calcConstraintForces	(	const SimTK::State &	state,
		SimTK::Vector_< SimTK::SpatialVec > &	bodyForcesInParent,
		SimTK::Vector &	mobilityForces
	)			`[virtual]`

Ask the RollingOnSurfaceConstraint for the forces it is imposing on the system Simbody multibody system must be realized to at least position Returns: the bodyForces on those bodies being constrained (constrainedBodies) a SpatialVec (6 components) describing resulting torque and force mobilityForces acting along constrained mobilities.

Parameters:

	state	State of model
	bodyForcesInParent	is a Vector of SpatialVecs contain constraint forces
	mobilityForces	is a Vector of forces that act along the constrained mobilitities associated with this constraint

Reimplemented from OpenSim::Constraint.

Object * RollingOnSurfaceConstraint::copy ( ) const [virtual]

Copy this body and return a pointer to the copy.

The copy constructor for this class is used.

Returns:: Pointer to a copy of this OpenSim::Body.

Reimplemented from OpenSim::UnilateralConstraint.

void RollingOnSurfaceConstraint::copyData ( const RollingOnSurfaceConstraint & aConstraint )

Copy data members from one RollingOnSurfaceConstraint to another.

Parameters:

aConstraint

RollingOnSurfaceConstraint to be copied.

Reimplemented from OpenSim::UnilateralConstraint.

bool RollingOnSurfaceConstraint::getIsDisabled ( const SimTK::State & state ) const [virtual]

Get whether or not the RollingOnSurfaceConstraint is disabled.

Simbody multibody system instance is realized every time the isDisabled changes, BUT multiple sets to the same value have no cost.

Parameters:

isDisabled

If true the constraint is disabled; if false the constraint is enabled.

Reimplemented from OpenSim::Constraint.

RollingOnSurfaceConstraint & RollingOnSurfaceConstraint::operator= ( const RollingOnSurfaceConstraint & aConstraint )

Assignment operator.

Returns:: Reference to this object.

Reimplemented from OpenSim::UnilateralConstraint.

void OpenSim::RollingOnSurfaceConstraint::setContactPointSurfaceBody ( SimTK::Vec3 point )

bool RollingOnSurfaceConstraint::setIsDisabled	(	SimTK::State &	state,
		bool	isDisabled,
		std::vector< bool >	shouldBeOn
	)

bool RollingOnSurfaceConstraint::setIsDisabled	(	SimTK::State &	state,
		bool	isDisabled
	)			`[virtual]`

Set whether or not the RollingOnSurfaceConstraint is disabled.

Since the constraint is composed of multiple constraints, this method can diable the constraints, but enabling is not guaranteed. For example, if the unilateral conditions are violated the constraint will be disabled.

Parameters:

isDisabled

If true the constraint is disabled; if false the constraint is enabled.