Description

Base class for joints implemented using the "lock formulation".

Derived classes provide models for revolute, prismatic, spherical, etc. Note that certain kinematic joints (e.g., Universal) cannot be modeled using the lock formulation. Joints of this type can optionally specify 'limits' over upper-lower motions of their respective degrees of freedom, using the ChLinkLimit objects.

#include <ChLinkLock.h>

Inheritance diagram for chrono::ChLinkLock:

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Collaboration diagram for chrono::ChLinkLock:

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Public Types
using	ChConstraintVectorX = Eigen::Matrix< double, Eigen::Dynamic, 1, Eigen::ColMajor, 7, 1 >

using	ChConstraintMatrixX6 = Eigen::Matrix< double, Eigen::Dynamic, BODY_DOF, Eigen::RowMajor, 7, BODY_DOF >

using	ChConstraintMatrixX7 = Eigen::Matrix< double, Eigen::Dynamic, BODY_QDOF, Eigen::RowMajor, 7, BODY_QDOF >

Public Member Functions
	ChLinkLock ()
	Default constructor. Builds a ChLinkLockSpherical.

	ChLinkLock (const ChLinkLock &other)
	Copy constructor.

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

int	RestoreRedundant () override
	If some constraint is redundant, return to normal state.

virtual void	SetDisabled (bool mdis) override
	Enable/disable all constraints of the link.

virtual void	SetBroken (bool mon) override
	For example, a 3rd party software can set the 'broken' status via this method.

ChLinkMask &	GetMask ()
	Get the link mask (a container for the ChConstraint items).

virtual void	SetUpMarkers (ChMarker mark1, ChMarker mark2) override
	Set the two markers associated with this link.

ChLinkForce &	GetForce_D ()
	Accessors for internal forces on free degrees of freedom. More...

ChLinkForce &	GetForce_R ()

ChLinkForce &	GetForce_X ()

ChLinkForce &	GetForce_Y ()

ChLinkForce &	GetForce_Z ()

ChLinkForce &	GetForce_Rx ()

ChLinkForce &	GetForce_Ry ()

ChLinkForce &	GetForce_Rz ()

ChLinkLimit &	GetLimit_X ()
	Accessors for limits on free degrees of freedom. More...

ChLinkLimit &	GetLimit_Y ()

ChLinkLimit &	GetLimit_Z ()

ChLinkLimit &	GetLimit_Rx ()

ChLinkLimit &	GetLimit_Ry ()

ChLinkLimit &	GetLimit_Rz ()

ChLinkLimit &	GetLimit_Rp ()

ChLinkLimit &	GetLimit_D ()

virtual int	GetDOC () override
	Get the number of scalar constraints for this link.

virtual int	GetDOC_c () override
	Get the number of bilateral constraints for this link.

virtual int	GetDOC_d () override
	Get the number of unilateral constraints for this link.

const ChConstraintVectorX &	GetC () const
	Link violation (residuals of the link constraint equations).

const ChConstraintVectorX &	GetC_dt () const
	Time derivatives of link violation.

const ChConstraintVectorX &	GetC_dtdt () const
	Second time derivatives of link violation.

const ChConstraintMatrixX7 &	GetCq1 () const
	The jacobian (body n.1 part, i.e. columns= 7 , rows= ndoc)

const ChConstraintMatrixX7 &	GetCq2 () const
	The jacobian (body n.2 part, i.e. columns= 7 , rows= ndoc)

const ChConstraintMatrixX6 &	GetCqw1 () const
	The jacobian for Wl (col 6, rows= ndoc), as [Cqw1_rot]=[Cq_rot]*[Gl_1]'.

const ChConstraintMatrixX6 &	GetCqw2 () const
	The jacobian for Wl (col 6, rows= ndoc) as [Cqw2_rot]=[Cq_rot]*[Gl_2]'.

const ChConstraintVectorX &	GetQc () const
	The gamma vector used in dynamics, [Cq]x''=Qc.

const ChConstraintVectorX &	GetCt () const
	The Ct vector used in kinematics, [Cq]x'=Ct.

const ChConstraintVectorX &	GetReact () const
	Access the reaction vector, after dynamics computations.

virtual void	UpdateState ()
	Given current time and body state, computes the constraint differentiation to get the the state matrices Cq1, Cq2, Qc, Ct , and also C, C_dt, C_dtd.

virtual void	UpdateForces (double mytime) override
	Updates the local F, M forces adding penalties from ChLinkLimit objects, if any.

void	UpdateCqw ()
	Updates Cqw1 and Cqw2 given updated Cq1 and Cq2, i.e. More...

virtual void	Update (double mytime, bool update_assets=true) override
	Full update. More...

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

virtual void	ArchiveIN (ChArchiveIn &marchive) override
	Method to allow deserialization of transient data from archives.

Public Member Functions inherited from chrono::ChLinkMarkers
ChMarker *	GetMarker1 ()
	Return the 1st referenced marker (the 'slave' marker, owned by 1st body)

ChMarker *	GetMarker2 ()
	Return the 2nd referenced marker (the 'master' marker, owned by 2nd body)

void	SetMarkID1 (int mid)

void	SetMarkID2 (int mid)

int	GetMarkID1 ()

int	GetMarkID2 ()

bool	ReferenceMarkers (ChMarker mark1, ChMarker mark2)
	Shortcut: set markers and marker IDs at once.

virtual void	Initialize (std::shared_ptr< ChMarker > mark1, std::shared_ptr< ChMarker > mark2)
	Use this function after link creation, to initialize the link from two markers to join. More...

virtual void	Initialize (std::shared_ptr< ChBody > mbody1, std::shared_ptr< ChBody > mbody2, const ChCoordsys<> &mpos)
	Use this function after link creation, to initialize the link from two joined rigid bodies. More...

virtual void	Initialize (std::shared_ptr< ChBody > mbody1, std::shared_ptr< ChBody > mbody2, bool pos_are_relative, const ChCoordsys<> &mpos1, const ChCoordsys<> &mpos2)
	Use this function after link creation, to initialize the link from two joined rigid bodies. More...

virtual ChCoordsys	GetLinkRelativeCoords () override
	Get the link coordinate system, expressed relative to Body2 (the 'master' body). More...

virtual ChFrame	GetAssetsFrame (unsigned int nclone=0) override
	Get the master coordinate system for the assets (this will return the absolute coordinate system of the 'master' marker2)

virtual void	UpdateRelMarkerCoords ()
	Updates auxiliary quantities for all relative degrees of freedom of the two markers.

virtual void	IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
	Adds force to residual R, as R= Fc NOTE: here the off offset in R is NOT used because add F at the TWO offsets of the two connected bodies, so it is assumed that offsets for Body1 and Body2 variables have been already set properly!

virtual void	ConstraintsFbLoadForces (double factor=1) override
	Overrides the empty behaviour of the parent ChLink implementation, which does not consider any user-imposed force between the two bodies. More...

const Coordsys &	GetRelM () const
	Relative position of marker 1 respect to marker 2.

const Coordsys &	GetRelM_dt () const
	Relative speed of marker 1 respect to marker 2.

const Coordsys &	GetRelM_dtdt () const
	Relative acceleration of marker 1 respect to marker 2.

double	GetRelAngle () const
	Relative rotation angle of marker 1 respect to marker 2 (best with revolute joints..).

const ChVector &	GetRelAxis () const
	Relative finite rotation axis of marker 1 respect to marker 2.

const ChVector &	GetRelRotaxis () const

const ChVector &	GetRelWvel () const
	Relative angular speed of marker 1 respect to marker 2.

const ChVector &	GetRelWacc () const
	Relative angular acceleration of marker 1 respect to marker 2.

double	GetDist () const
	Relative 'polar' distance of marker 1 respect to marker 2.

double	GetDist_dt () const
	Relative speed of marker 1 respect to marker 2, along the polar distance vector.

const ChVector &	GetC_force () const
	Get the total applied force accumulators (force, momentum) in link coords. More...

const ChVector &	GetC_torque () const

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

int	GetLeftDOF ()
	Get the number of free degrees of freedom left by this link, between two bodies.

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

ChBodyFrame *	GetBody1 ()
	Get the constrained body '1', the 'slave' body.

ChBodyFrame *	GetBody2 ()
	Get the constrained body '2', the 'master' body.

virtual ChCoordsys	GetLinkAbsoluteCoords () override
	Get the link coordinate system in absolute reference. More...

virtual ChVector	Get_react_force () override
	Get reaction force, expressed in link coordinate system.

virtual ChVector	Get_react_torque () override
	Get reaction torque, expressed in link coordinate system.

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.

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

bool	IsActive ()
	An important function! Tells if the link is currently active, in general, that is tells if it must be included into the system solver or not. More...

virtual bool	IsRequiringWaking ()
	Tells if this link requires that the connected ChBody objects must be waken if they are sleeping. 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() and also add to new collision system / remove from old coll.system.

void	AddAsset (std::shared_ptr< ChAsset > masset)
	Add an optional asset (it can be used to define visualization shapes, es ChSphereShape, or textures, or custom attached properties that the user can define by creating his class inherited from ChAsset)

std::vector< std::shared_ptr< ChAsset > > &	GetAssets ()
	Access to the list of optional assets.

std::shared_ptr< ChAsset >	GetAssetN (unsigned int num)
	Access the Nth asset in the list of optional assets.

virtual unsigned int	GetAssetsFrameNclones ()
	Optionally, a ChPhysicsItem can return multiple asset coordinate systems; this can be helpful if, for example, when a ChPhysicsItem contains 'clones' with the same assets (ex. More...

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

virtual void	SyncCollisionModels ()
	If this physical item contains one or more collision models, synchronize their coordinates and bounding boxes to the state of the item.

virtual void	AddCollisionModelsToSystem ()
	If this physical item contains one or more collision models, add them to the system's collision engine.

virtual void	RemoveCollisionModelsFromSystem ()
	If this physical item contains one or more collision models, remove them from the system's collision engine.

virtual void	GetTotalAABB (ChVector<> &bbmin, ChVector<> &bbmax)
	Get the entire AABB axis-aligned bounding box of the object. More...

virtual void	GetCenter (ChVector<> &mcenter)
	Get a symbolic 'center' of the object. More...

virtual void	StreamINstate (ChStreamInBinary &mstream)
	Method to deserialize only the state (position, speed) Must be implemented by child classes.

virtual void	StreamOUTstate (ChStreamOutBinary &mstream)
	Method to serialize only the state (position, speed) Must be implemented by child classes.

virtual void	Setup ()
	This might recompute the number of coordinates, DOFs, constraints, in case this might change (ex in ChAssembly), as well as state offsets of contained items (ex in ChMesh)

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

virtual int	GetDOF ()
	Get the number of scalar coordinates (variables), if any, in this item. More...

virtual int	GetDOF_w ()
	Get the number of scalar coordinates of variables derivatives (usually = DOF, but might be different than DOF, ex. More...

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	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	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	InjectVariables (ChSystemDescriptor &mdescriptor)
	Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.

virtual void	InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
	Tell to a system descriptor that there are items of type ChKblock in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.

virtual void	KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
	Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...

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

int	GetIdentifier () const
	Gets the numerical identifier of the object.

void	SetIdentifier (int id)
	Sets the numerical identifier of the object.

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

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

const char *	GetName () const
	Gets the name of the object as C Ascii null-terminated string -for reading only!

void	SetName (const char myname[])
	Sets the name of this object, as ascii string.

std::string	GetNameString () const
	Gets the name of the object as C Ascii null-terminated string.

void	SetNameString (const std::string &myname)
	Sets the name of this object, as std::string.

void	MFlagsSetAllOFF (int &mflag)

void	MFlagsSetAllON (int &mflag)

void	MFlagSetON (int &mflag, int mask)

void	MFlagSetOFF (int &mflag, int mask)

int	MFlagGet (int &mflag, int mask)

virtual std::string &	ArchiveContainerName ()

Protected Types
enum	LinkType { LOCK, SPHERICAL, POINTPLANE, POINTLINE, CYLINDRICAL, PRISMATIC, PLANEPLANE, OLDHAM, REVOLUTE, FREE, ALIGN, PARALLEL, PERPEND, TRAJECTORY, CLEARANCE, REVOLUTEPRISMATIC }
	Type of link-lock.

Protected Member Functions
void	BuildLink ()
	Resize matrices and initializes all mask-dependent quantities. More...

void	BuildLinkType (LinkType link_type)
	Set the mask and then resize matrices.

void	BuildLink (bool x, bool y, bool z, bool e0, bool e1, bool e2, bool e3)

void	ChangeLinkType (LinkType new_link_type)

virtual void	IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L) override
	From global reaction vector to item's reaction forces. More...

virtual void	IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L) override
	From item's reaction forces to global reaction vector. More...

virtual void	IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c) override
	Takes the term Cq'L, scale and adds to R at given offset: R += cCq'*L. More...

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

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

virtual void	IntToDescriptor (const unsigned int off_v, const ChStateDelta &v, const ChVectorDynamic<> &R, const unsigned int off_L, const ChVectorDynamic<> &L, const ChVectorDynamic<> &Qc) override
	Prepare variables and constraints to accommodate a solution: More...

virtual void	IntFromDescriptor (const unsigned int off_v, ChStateDelta &v, const unsigned int off_L, ChVectorDynamic<> &L) override
	After a solver solution, fetch values from variables and constraints into vectors: More...

virtual void	InjectConstraints (ChSystemDescriptor &mdescriptor) override
	Tell to a system descriptor that there are constraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.

virtual void	ConstraintsBiReset () override
	Sets to zero the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_C (double factor=1, double recovery_clamp=0.1, bool do_clamp=false) override
	Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_Ct (double factor=1) override
	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) override
	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	ConstraintsLoadJacobians () override
	Adds the current jacobians in encapsulated ChConstraints.

virtual void	ConstraintsFetch_react (double factor=1) override
	Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...

Protected Member Functions inherited from chrono::ChLinkMarkers
	ChLinkMarkers (const ChLinkMarkers &other)

Protected Attributes
LinkType	type
	type of link_lock joint

ChLinkMaskLF	mask
	scalar constraints

int	ndoc
	number of degrees of constraint

int	ndoc_c
	number of degrees of constraint (bilateral constraintss)

int	ndoc_d
	number of degrees of constraint (unilateral constraints, excluding joint limits)

std::unique_ptr< ChLinkForce >	force_D
	the force acting on the straight line m1-m2 (distance)

std::unique_ptr< ChLinkForce >	force_R
	the torque acting about rotation axis

std::unique_ptr< ChLinkForce >	force_X
	the force acting along X dof

std::unique_ptr< ChLinkForce >	force_Y
	the force acting along Y dof

std::unique_ptr< ChLinkForce >	force_Z
	the force acting along Z dof

std::unique_ptr< ChLinkForce >	force_Rx
	the torque acting about Rx dof

std::unique_ptr< ChLinkForce >	force_Ry
	the torque acting about Ry dof

std::unique_ptr< ChLinkForce >	force_Rz
	the torque acting about Rz dof

double	d_restlength
	the rest length of the "d_spring" spring

std::unique_ptr< ChLinkLimit >	limit_X
	the upper/lower limits for X dof

std::unique_ptr< ChLinkLimit >	limit_Y
	the upper/lower limits for Y dof

std::unique_ptr< ChLinkLimit >	limit_Z
	the upper/lower limits for Z dof

std::unique_ptr< ChLinkLimit >	limit_Rx
	the upper/lower limits for Rx dof

std::unique_ptr< ChLinkLimit >	limit_Ry
	the upper/lower limits for Ry dof

std::unique_ptr< ChLinkLimit >	limit_Rz
	the upper/lower limits for Rz dof

std::unique_ptr< ChLinkLimit >	limit_Rp
	the polar (conical) limit for "shoulder"rotation

std::unique_ptr< ChLinkLimit >	limit_D
	the polar (conical) limit for "shoulder"rotation

ChConstraintVectorX	C
	C(q,q_dt,t), the constraint violations.

ChConstraintVectorX	C_dt
	Speed constraint violations.

ChConstraintVectorX	C_dtdt
	Acceleration constraint violations.

ChConstraintMatrixX7	Cq1
	[Cq1], the jacobian of the constraint, for coords1, [ndoc,7]

ChConstraintMatrixX7	Cq2
	[Cq2], the jacobian of the constraint, for coords2. [ndoc,7]

ChConstraintMatrixX6	Cqw1
	[Cqw1], the jacobian [ndoc,6] for 3 Wl rot.coordinates instead of quaternions

ChConstraintMatrixX6	Cqw2
	[Cqw2], the jacobian [ndoc,6] for 3 Wl rot.coordinates instead of quaternions

ChConstraintVectorX	Qc
	{Qc}, the known part, {Qc}=-{C_dtdt}-([Cq]{q_dt})q-2[Cq_dt]{q_dt}

ChConstraintVectorX	Ct
	partial derivative of the link kin. equation wrt to time

ChConstraintVectorX	react
	{l}, the lagrangians forces in the constraints

ChMatrixNM< double, 7, BODY_QDOF >	Cq1_temp

ChMatrixNM< double, 7, BODY_QDOF >	Cq2_temp

ChVectorN< double, 7 >	Qc_temp

Coordsys	Ct_temp

Protected Attributes inherited from chrono::ChLinkMarkers
ChMarker *	marker1
	slave coordsys

ChMarker *	marker2
	master coordsys, =0 if liked to ground

int	markID1
	unique identifier for markers 1 & 2,

int	markID2
	when using plugin dynamic hierarchies

Coordsys	relM
	relative marker position 2-1

Coordsys	relM_dt
	relative marker speed

Coordsys	relM_dtdt
	relative marker acceleration

double	relAngle
	relative angle of rotation

ChVector	relAxis
	relative axis of rotation

ChVector	relRotaxis
	relative rotaion vector =angle*axis

ChVector	relWvel
	relative angular speed

ChVector	relWacc
	relative angular acceleration

double	dist
	the distance between the two origins of markers,

double	dist_dt
	the speed between the two origins of markers

ChVector	C_force
	internal force applied by springs/dampers/actuators

ChVector	C_torque
	internal torque applied by springs/dampers/actuators

ChVector	PQw

ChVector	PQw_dt

ChVector	PQw_dtdt

ChQuaternion	q_AD

ChQuaternion	q_BC

ChQuaternion	q_8

ChVector	q_4

Protected Attributes inherited from chrono::ChLink
ChBodyFrame *	Body1
	first connected body

ChBodyFrame *	Body2
	second connected body

ChVector	react_force
	store the xyz reactions, expressed in local coordinate system of link;

ChVector	react_torque
	store the 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::vector< std::shared_ptr< ChAsset > >	assets
	set of assets

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
	the time of simulation for the object

Friends
class	ChConveyor

Member Function Documentation

◆ BuildLink()

void chrono::ChLinkLock::BuildLink ( )

protected

Resize matrices and initializes all mask-dependent quantities.

Sets number of DOF and number DOC based on current mask information.

◆ ConstraintsFetch_react()

void chrono::ChLinkLock::ConstraintsFetch_react ( double factor = 1 )

overrideprotectedvirtual

Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints.

Mostly used after the solver provided the solution in ChConstraints. Also, should convert the reactions obtained from dynamical simulation, from link space to intuitive react_force and react_torque.

Reimplemented from chrono::ChPhysicsItem.

◆ GetForce_D()

ChLinkForce & chrono::ChLinkLock::GetForce_D ( )

Accessors for internal forces on free degrees of freedom.

These functions provide access to initialize and set parameters for link forces acting on different degrees of freedom of the joint. Note that they use "lazy initialization"; an internal link force object is created on the first invocation of the corresponding accessor function.

◆ GetLimit_X()

ChLinkLimit & chrono::ChLinkLock::GetLimit_X ( )

Accessors for limits on free degrees of freedom.

These functions provide access to initialize and set parameters for link limits on different free degrees of freedom of the joint. Note that they use "lazy initialization"; an internal link limit object is created on the first invocation of the corresponding accessor function.

◆ IntFromDescriptor()

void chrono::ChLinkLock::IntFromDescriptor	(	const unsigned int	off_v,
		ChStateDelta &	v,
		const unsigned int	off_L,
		ChVectorDynamic<> &	L
	)

overrideprotectedvirtual

After a solver solution, fetch values from variables and constraints into vectors:

Parameters

off_v	offset for v
v	vector to where the q 'unknowns' term of the variables will be copied
off_L	offset for L
L	vector to where L 'lagrangian ' term of the constraints will be copied

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadConstraint_C()

void chrono::ChLinkLock::IntLoadConstraint_C	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c,
		bool	do_clamp,
		double	recovery_clamp
	)

overrideprotectedvirtual

Takes the term C, scale and adds to Qc at given offset: Qc += c*C.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*C
c	a scaling factor
do_clamp	apply clamping to c*C?
recovery_clamp	value for min/max clamping of c*C

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadConstraint_Ct()

void chrono::ChLinkLock::IntLoadConstraint_Ct	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c
	)

overrideprotectedvirtual

Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*Ct
c	a scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadResidual_CqL()

void chrono::ChLinkLock::IntLoadResidual_CqL	(	const unsigned int	off_L,
		ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	L,
		const double	c
	)

overrideprotectedvirtual

Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L.

Parameters

off_L	offset in L multipliers
R	result: the R residual, R += cCq'L
L	the L vector
c	a scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateGatherReactions()

void chrono::ChLinkLock::IntStateGatherReactions	(	const unsigned int	off_L,
		ChVectorDynamic<> &	L
	)

overrideprotectedvirtual

From item's reaction forces to global reaction vector.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateScatterReactions()

void chrono::ChLinkLock::IntStateScatterReactions	(	const unsigned int	off_L,
		const ChVectorDynamic<> &	L
	)

overrideprotectedvirtual

From global reaction vector to item's reaction forces.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChPhysicsItem.

◆ IntToDescriptor()

void chrono::ChLinkLock::IntToDescriptor	(	const unsigned int	off_v,
		const ChStateDelta &	v,
		const ChVectorDynamic<> &	R,
		const unsigned int	off_L,
		const ChVectorDynamic<> &	L,
		const ChVectorDynamic<> &	Qc
	)

overrideprotectedvirtual

Prepare variables and constraints to accommodate a solution:

Parameters

off_v	offset for v and R
v	vector that will be copied into the q 'unknowns' term of the variables (for warm starting)
R	vector that will be copied into the F 'force' term of the variables
off_L	offset for L and Qc
L	vector that will be copied into the L 'lagrangian ' term of the constraints (for warm starting)
Qc	vector that will be copied into the Qb 'constraint' term of the constraints

Reimplemented from chrono::ChPhysicsItem.

◆ Update()

void chrono::ChLinkLock::Update	(	double	mytime,
		bool	update_assets = `true`
	)

overridevirtual

Full update.

Fills-in all the matrices of the link, and does all required calculations by calling specific Update functions in sequence:

    UpdateTime;
    UpdateRelMarkerCoords;
    UpdateState;
    UpdateCqw
    UpdateForces;

Reimplemented from chrono::ChLinkMarkers.

◆ UpdateCqw()

void chrono::ChLinkLock::UpdateCqw ( )

Updates Cqw1 and Cqw2 given updated Cq1 and Cq2, i.e.

computes the jacobians with 'Wl' rotational coordinates knowing the jacobians for body rotations in quaternion coordinates.

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

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

Description

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Protected Attributes

Friends

Member Function Documentation

◆ BuildLink()

◆ ConstraintsFetch_react()

◆ GetForce_D()

◆ GetLimit_X()

◆ IntFromDescriptor()

◆ IntLoadConstraint_C()

◆ IntLoadConstraint_Ct()

◆ IntLoadResidual_CqL()

◆ IntStateGatherReactions()

◆ IntStateScatterReactions()

◆ IntToDescriptor()

◆ Update()

◆ UpdateCqw()