Description

Class for modeling a universal joint between two two ChBodyFrame objects.

This joint is defined through 4 constraint equations between two marker frames, one on each body. Kinematically, these constraints impose the condition that the two marker origins coincide (3 constraints) and that two directions (one on each body) are always perpendicular. Together, these constraints model the cross in a physical universal joint.

#include <ChLinkUniversal.h>

Inheritance diagram for chrono::ChLinkUniversal:

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Collaboration diagram for chrono::ChLinkUniversal:

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Public Member Functions
	ChLinkUniversal (const ChLinkUniversal &other)

virtual ChLinkUniversal *	Clone () const override
	"Virtual" copy constructor (covariant return type).

virtual unsigned int	GetNumConstraintsBilateral () override
	Get the number of (bilateral) constraints introduced by this joint.

virtual ChFramed	GetFrame1Rel () const override
	Get the link frame 1, relative to body 1.

virtual ChFramed	GetFrame2Rel () const override
	Get the link frame 2, relative to body 2.

virtual ChVectorDynamic	GetConstraintViolation () const override
	Get the joint violation (residuals of the constraint equations)

void	Initialize (std::shared_ptr< ChBody > body1, std::shared_ptr< ChBody > body2, const ChFrame<> &frame)
	Initialize this joint by specifying the two bodies to be connected and a joint frame specified in the absolute frame. More...

void	Initialize (std::shared_ptr< ChBody > body1, std::shared_ptr< ChBody > body2, bool local, const ChFrame<> &frame1, const ChFrame<> &frame2)
	Initialize this joint by specifying the two bodies to be connected and the joint frames on each body. More...

virtual void	ArchiveOut (ChArchiveOut &archive_out) override
	Method to allow serialization of transient data to archives.

virtual void	ArchiveIn (ChArchiveIn &archive_in) override
	Method to allow deserialization of transient data from archives. More...

Public Member Functions inherited from chrono::ChLink
	ChLink (const ChLink &other)

virtual unsigned int	GetNumAffectedCoords () override
	Get the number of scalar variables affected by constraints in this link.

ChBodyFrame *	GetBody1 () const
	Get the constrained body 1.

ChBodyFrame *	GetBody2 () const
	Get the constrained body 2.

virtual ChFramed	GetFrame1Abs () const override
	Get the link frame 1, on body 1, expressed in the absolute frame.

virtual ChFramed	GetFrame2Abs () const override
	Get the link frame 2, on body 2, expressed in the absolute frame.

virtual ChWrenchd	GetReaction1 () const override
	Get the reaction force and torque on the 1st body, expressed in the link frame 1.

virtual ChWrenchd	GetReaction2 () const override
	Get the reaction force and torque on the 2nd body object, expressed in the link frame 2.

virtual void	UpdateTime (double mytime)
	Given new time, current body state, update time-dependent quantities in link state, for example motion laws, moving markers, etc. More...

virtual void	Update (bool update_assets=true) override
	As above, but with current time.

virtual void	UpdatedExternalTime (double prevtime, double time)
	Called from a external package (i.e. a plugin, a CAD app.) to report that time has changed.

Public Member Functions inherited from chrono::ChLinkBase
	ChLinkBase (const ChLinkBase &other)

bool	IsValid ()
	Tells if the link data is currently valid. More...

void	SetValid (bool mon)
	Set the status of link validity.

bool	IsDisabled ()
	Tells if all constraints of this link are currently turned on or off by the user.

virtual void	SetDisabled (bool mdis)
	User can use this to enable/disable all the constraint of the link as desired.

bool	IsBroken ()
	Tells if the link is broken, for excess of pulling/pushing.

virtual void	SetBroken (bool mon)
	Set the 'broken' status vof this link.

virtual bool	IsActive () const override
	Return true if the link is currently active and thereofre included into the system solver. More...

virtual bool	IsRequiringWaking ()
	Tells if this link requires that the connected ChBody objects must be waken if they are sleeping. More...

virtual ChFrame	GetVisualModelFrame (unsigned int nclone=0) const override
	Get the reference frame (expressed in and relative to the absolute frame) of the visual model. More...

Public Member Functions inherited from chrono::ChPhysicsItem
	ChPhysicsItem (const ChPhysicsItem &other)

ChSystem *	GetSystem () const
	Get the pointer to the parent ChSystem().

virtual void	SetSystem (ChSystem *m_system)
	Set the pointer to the parent ChSystem(). More...

void	AddVisualModel (std::shared_ptr< ChVisualModel > model)
	Add an (optional) visualization model. More...

std::shared_ptr< ChVisualModel >	GetVisualModel () const
	Access the visualization model (if any). More...

void	AddVisualShape (std::shared_ptr< ChVisualShape > shape, const ChFrame<> &frame=ChFrame<>())
	Add the specified visual shape to the visualization model. More...

std::shared_ptr< ChVisualShape >	GetVisualShape (unsigned int i) const
	Access the specified visualization shape in the visualization model (if any). More...

void	AddVisualShapeFEA (std::shared_ptr< ChVisualShapeFEA > shapeFEA)
	Add the specified FEA visualization object to the visualization model. More...

std::shared_ptr< ChVisualShapeFEA >	GetVisualShapeFEA (unsigned int i) const
	Access the specified FEA visualization object in the visualization model (if any). More...

virtual unsigned int	GetNumVisualModelClones () const
	Return the number of clones of the visual model associated with this physics item. More...

void	AddCamera (std::shared_ptr< ChCamera > camera)
	Attach a ChCamera to this physical item. More...

std::vector< std::shared_ptr< ChCamera > >	GetCameras () const
	Get the set of cameras attached to this physics item.

virtual bool	IsCollisionEnabled () const
	Tell if the object is subject to collision. More...

virtual void	AddCollisionModelsToSystem (ChCollisionSystem *coll_sys) const
	Add to the provided collision system any collision models managed by this physics item. More...

virtual void	RemoveCollisionModelsFromSystem (ChCollisionSystem *coll_sys) const
	Remove from the provided collision system any collision models managed by this physics item. More...

virtual void	SyncCollisionModels ()
	Synchronize the position and bounding box of any collsion models managed by this physics item.

virtual ChAABB	GetTotalAABB () const
	Get the axis-aligned bounding box (AABB) of this object. More...

virtual ChVector3d	GetCenter () const
	Get a symbolic 'center' of the object. More...

virtual void	Setup ()
	Perform setup operations. More...

void	UpdateVisualModel ()
	Utility function to update only the associated visual assets (if any).

virtual void	ForceToRest ()
	Set zero speed (and zero accelerations) in state, without changing the position. More...

virtual unsigned int	GetNumCoordsPosLevel ()
	Get the number of coordinates at the position level. More...

virtual unsigned int	GetNumCoordsVelLevel ()
	Get the number of coordinates at the velocity level. More...

virtual unsigned int	GetNumConstraints ()
	Get the number of scalar constraints.

virtual unsigned int	GetNumConstraintsUnilateral ()
	Get the number of unilateral scalar constraints.

unsigned int	GetOffset_x ()
	Get offset in the state vector (position part)

unsigned int	GetOffset_w ()
	Get offset in the state vector (speed part)

unsigned int	GetOffset_L ()
	Get offset in the lagrangian multipliers.

void	SetOffset_x (const unsigned int moff)
	Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this.

void	SetOffset_w (const unsigned int moff)
	Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this.

void	SetOffset_L (const unsigned int moff)
	Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this.

virtual void	IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T)
	From item's state to global state vectors y={x,v} pasting the states at the specified offsets. More...

virtual void	IntStateScatter (const unsigned int off_x, const ChState &x, const unsigned int off_v, const ChStateDelta &v, const double T, bool full_update)
	From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets. More...

virtual void	IntStateGatherAcceleration (const unsigned int off_a, ChStateDelta &a)
	From item's state acceleration to global acceleration vector. More...

virtual void	IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a)
	From global acceleration vector to item's state acceleration. More...

virtual void	IntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv)
	Computes x_new = x + Dt , using vectors at specified offsets. More...

virtual void	IntStateGetIncrement (const unsigned int off_x, const ChState &x_new, const ChState &x, const unsigned int off_v, ChStateDelta &Dv)
	Computes Dt = x_new - x, using vectors at specified offsets. More...

virtual void	IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c)
	Takes the F force term, scale and adds to R at given offset: R += c*F. More...

virtual void	IntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c)
	Takes the Mv term, multiplying mass by a vector, scale and adds to R at given offset: R += cM*w. More...

virtual void	IntLoadLumpedMass_Md (const unsigned int off, ChVectorDynamic<> &Md, double &err, const double c)
	Adds the lumped mass to a Md vector, representing a mass diagonal matrix. More...

virtual void	IntLoadConstraint_Ct (const unsigned int off, ChVectorDynamic<> &Qc, const double c)
	Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...

virtual void	InjectVariables (ChSystemDescriptor &descriptor)
	Register with the given system descriptor any ChVariable objects associated with this item.

virtual void	InjectKRMMatrices (ChSystemDescriptor &descriptor)
	Register with the given system descriptor any ChKRMBlock objects associated with this item.

virtual void	LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor)
	Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. More...

virtual void	VariablesFbReset ()
	Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.

virtual void	VariablesFbLoadForces (double factor=1)
	Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.

virtual void	VariablesQbLoadSpeed ()
	Initialize the 'qb' part of the ChVariables with the current value of speeds. More...

virtual void	VariablesFbIncrementMq ()
	Adds M*q (masses multiplied current 'qb') to Fb, ex. More...

virtual void	VariablesQbSetSpeed (double step=0)
	Fetches the item speed (ex. More...

virtual void	VariablesQbIncrementPosition (double step)
	Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More...

virtual void	ConstraintsBiLoad_Ct (double factor=1)
	Adds the current Ct (partial t-derivative, as in C_dt=0-> [Cq]*q_dt=-Ct) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_Qc (double factor=1)
	Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsFbLoadForces (double factor=1)
	Adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints.

Public Member Functions inherited from chrono::ChObj
	ChObj (const ChObj &other)

int	GetIdentifier () const
	Get the unique integer identifier of this object. More...

void	SetTag (int tag)
	Set an object integer tag (default: -1). More...

int	GetTag () const
	Get the tag of this object.

void	SetName (const std::string &myname)
	Set the name of this object.

const std::string &	GetName () const
	Get the name of this object.

double	GetChTime () const
	Gets the simulation time of this object.

void	SetChTime (double m_time)
	Sets the simulation time of this object.

virtual std::string &	ArchiveContainerName ()

Additional Inherited Members
Protected Member Functions inherited from chrono::ChObj
int	GenerateUniqueIdentifier ()

Protected Attributes inherited from chrono::ChLink
ChBodyFrame *	m_body1
	first connected body

ChBodyFrame *	m_body2
	second connected body

ChVector3d	react_force
	xyz reactions, expressed in local coordinate system of link;

ChVector3d	react_torque
	torque reactions, expressed in local coordinate system of link;

Protected Attributes inherited from chrono::ChLinkBase
bool	disabled
	all constraints of link disabled because of user needs

bool	valid
	link data is valid

bool	broken
	link is broken because of excessive pulling/pushing.

Protected Attributes inherited from chrono::ChPhysicsItem
ChSystem *	system
	parent system

std::shared_ptr< ChVisualModelInstance >	vis_model_instance
	instantiated visualization model

std::vector< std::shared_ptr< ChCamera > >	cameras
	set of cameras

unsigned int	offset_x
	offset in vector of state (position part)

unsigned int	offset_w
	offset in vector of state (speed part)

unsigned int	offset_L
	offset in vector of lagrangian multipliers

Protected Attributes inherited from chrono::ChObj
double	ChTime
	object simulation time

std::string	m_name
	object name

int	m_identifier
	object unique identifier

int	m_tag
	user-supplied tag

Member Function Documentation

◆ ArchiveIn()

void chrono::ChLinkUniversal::ArchiveIn ( ChArchiveIn & archive_in )

overridevirtual

Method to allow deserialization of transient data from archives.

Method to allow de serialization of transient data from archives.

Reimplemented from chrono::ChLink.

◆ Initialize() [1/2]

void chrono::ChLinkUniversal::Initialize	(	std::shared_ptr< ChBody >	body1,
		std::shared_ptr< ChBody >	body2,
		bool	local,
		const ChFrame<> &	frame1,
		const ChFrame<> &	frame2
	)

Initialize this joint by specifying the two bodies to be connected and the joint frames on each body.

If local = true, it is assumed that these quantities are specified in the local body frames. Otherwise, it is assumed that they are specified in the absolute frame.

Parameters

body1	first body frame
body2	second body frame
local	true if data given in body local frames
frame1	joint frame on body 1
frame2	joint frame on body 2

◆ Initialize() [2/2]

void chrono::ChLinkUniversal::Initialize	(	std::shared_ptr< ChBody >	body1,
		std::shared_ptr< ChBody >	body2,
		const ChFrame<> &	frame
	)

Initialize this joint by specifying the two bodies to be connected and a joint frame specified in the absolute frame.

Two local joint frames, one on each body, are constructed so that they coincide with the specified global joint frame at the current configuration. The kinematics of the universal joint are obtained by imposing that the origins of these two frames are the same and that the X axis of the joint frame on body 1 and the Y axis of the joint frame on body 2 are perpendicular.

Parameters

body1	first body frame
body2	second body frame
frame	joint frame (in absolute frame)

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono/physics/ChLinkUniversal.h
/builds/uwsbel/chrono/src/chrono/physics/ChLinkUniversal.cpp

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ArchiveIn()

◆ Initialize() [1/2]

◆ Initialize() [2/2]