Description

Base class for all link joints which use a 'six degrees of freedom' mask and auxiliary matrices to store jacobians.

The management of jacobian matrices, as well as other auxiliary matrices, is automatic as soon as the mask is changed. Also, links inherited from this class inherit six ChLinkForce objects, to set inner spring-damper features for each degree of freedom.

#include <ChLinkMasked.h>

Inheritance diagram for chrono::ChLinkMasked:
Collaboration diagram for chrono::ChLinkMasked:

Public Member Functions

 ChLinkMasked (const ChLinkMasked &other)
 
virtual ChLinkMaskedClone () const override
 "Virtual" copy constructor (covariant return type).
 
void ChangeLinkMask (ChLinkMask *new_mask)
 Must be called after whatever change the mask of the link, in order to update auxiliary matrices sizes... More...
 
void ChangedLinkMask ()
 Must be called after whatever change the mask of the link, in order to update auxiliary matrices sizes... More...
 
int RestoreRedundant () override
 If some constraint is redundant, return to normal state. More...
 
virtual void SetDisabled (bool mdis) override
 User can use this to enable/disable all the constraint of the link as desired. More...
 
virtual void SetBroken (bool mon) override
 Ex:3rd party software can set the 'broken' status via this method.
 
ChLinkMaskGetMask ()
 Get the pointer to the link mask, ie. More...
 
virtual void SetUpMarkers (ChMarker *mark1, ChMarker *mark2) override
 overwrites inherited implementation of this method
 
virtual int GetDOC () override
 Get the number of scalar constraints, if any, in this item.
 
virtual int GetDOC_c () override
 Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this. More...
 
virtual int GetDOC_d () override
 Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this. More...
 
virtual void IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L) override
 From item's reaction forces to global reaction vector.
 
virtual void IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L) override
 From global reaction vector to item's reaction forces.
 
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 += c*Cq'*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 for a solution: From a vector R into the F 'force' term of the variables From a vector Qc into the Qb 'constraint' term of the constraints From a vector v into the q 'unknowns' term of the variables (for warm starting) From a vector L into the L 'lagrangian ' term of the constraints (for warm starting) 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: To a vector v from the q 'unknowns' term of the variables To a vector L from the L 'lagrangian ' term of the constraints. More...
 
virtual void InjectConstraints (ChSystemDescriptor &mdescriptor) override
 Tell to a system descriptor that there are contraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this. More...
 
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...
 
virtual void UpdateState ()
 This is expected to update the values in C, C_dt, C_dtdt, in jacobians Cq1 and Cq2, in Qc and in Ct. More...
 
virtual void UpdateCqw ()
 Updates Cqw1 and Cqw2 given updated Cq1 and Cq2, i.e. More...
 
virtual void UpdateForces (double mytime) override
 Inherits, and updates the C_force and C_torque 'intuitive' forces, adding the effects of the contained ChLinkForce objects. More...
 
virtual void Update (double mytime, bool update_assets=true) override
 This following "complete" update functions actually fill all the matrices of the link, and does all calculus, by calling all the previous Update functions in sequence. More...
 
ChMatrixGetC ()
 Link violation (residuals of the link constraint equations)
 
ChMatrixGetC_dt ()
 Time derivatives of link violations.
 
ChMatrixGetC_dtdt ()
 Double time derivatives of link violations.
 
ChMatrixGetCq1 ()
 The jacobian (body n.1 part, i.e. columns= 7 , rows= ndoc)
 
ChMatrixGetCq2 ()
 The jacobian (body n.2 part, i.e. columns= 7 , rows= ndoc)
 
ChMatrixGetCqw1 ()
 The jacobian for Wl (col 6, rows= ndoc), as [Cqw1_rot]=[Cq_rot]*[Gl_1]'.
 
ChMatrixGetCqw2 ()
 The jacobian for Wl (col 6, rows= ndoc) as [Cqw2_rot]=[Cq_rot]*[Gl_2]'.
 
ChMatrixGetQc ()
 The gamma vector used in dynamics, [Cq]x''=Qc.
 
ChMatrixGetCt ()
 The Ct vector used in kinematics, [Cq]x'=Ct.
 
ChMatrixGetReact ()
 Access the reaction vector, after dynamics computations.
 
ChLinkForceGetForce_D ()
 
ChLinkForceGetForce_R ()
 
ChLinkForceGetForce_X ()
 
ChLinkForceGetForce_Y ()
 
ChLinkForceGetForce_Z ()
 
ChLinkForceGetForce_Rx ()
 
ChLinkForceGetForce_Ry ()
 
ChLinkForceGetForce_Rz ()
 
void SetForce_D (ChLinkForce *m_for)
 
void SetForce_R (ChLinkForce *m_for)
 
void SetForce_X (ChLinkForce *m_for)
 
void SetForce_Y (ChLinkForce *m_for)
 
void SetForce_Z (ChLinkForce *m_for)
 
void SetForce_Rx (ChLinkForce *m_for)
 
void SetForce_Ry (ChLinkForce *m_for)
 
void SetForce_Rz (ChLinkForce *m_for)
 
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. More...
 
- Public Member Functions inherited from chrono::ChPhysicsItem
 ChPhysicsItem (const ChPhysicsItem &other)
 
ChSystemGetSystem () 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< ChAssetGetAssetN (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, sinchronize their coordinates and bounding boxes to the state of the item. More...
 
virtual void AddCollisionModelsToSystem ()
 If this physical item contains one or more collision models, add them to the system's collision engine. More...
 
virtual void RemoveCollisionModelsFromSystem ()
 If this physical item contains one or more collision models, remove them from the system's collision engine. More...
 
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. More...
 
virtual void StreamOUTstate (ChStreamOutBinary &mstream)
 Method to serialize only the state (position, speed) Must be implemented by child classes. More...
 
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)
 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 M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*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. More...
 
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. More...
 
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)
 

Protected Member Functions

void BuildLink (ChLinkMask *new_mask)
 
void BuildLink ()
 
void DestroyLink ()
 

Static Protected Member Functions

static void Transform_Cq_to_Cqw (ChMatrix<> *mCq, ChMatrix<> *mCqw, ChBodyFrame *mbody)
 UPDATING PROCEDURES.
 

Protected Attributes

ChLinkMaskmask
 scalar constraints
 
int ndoc
 number of DOC, degrees of costraint
 
int ndoc_c
 number of DOC, degrees of costraint (only bilaterals)
 
int ndoc_d
 number of DOC, degrees of costraint (only unilaterals)
 
ChLinkForceforce_D
 the force acting on the straight line m1-m2 (distance)
 
ChLinkForceforce_R
 the torque acting about rotation axis
 
ChLinkForceforce_X
 the force acting along X dof
 
ChLinkForceforce_Y
 the force acting along Y dof
 
ChLinkForceforce_Z
 the force acting along Z dof
 
ChLinkForceforce_Rx
 the torque acting about Rx dof
 
ChLinkForceforce_Ry
 the torque acting about Ry dof
 
ChLinkForceforce_Rz
 the torque acting about Rz dof
 
double d_restlength
 the rest length of the "d_spring" spring
 
ChMatrixC
 {C(q,q_dt,t)}, <<<<!!! that is
 
ChMatrixC_dt
 the violation= relC = C(q,qdt,t)
 
ChMatrixC_dtdt
 also speed violations. and acc violations
 
ChMatrixCq1
 [Cq1], the jacobian of the constraint, for coords1, [ndoc,7]
 
ChMatrixCq2
 [Cq2], the jacobian of the constraint, for coords2. [ndoc,7]
 
ChMatrixCqw1
 [Cqw1], the jacobian [ndoc,6] for 3 Wl rot.coordinates instead of quaternions
 
ChMatrixCqw2
 [Cqw2], the jacobian [ndoc,6] for 3 Wl rot.coordinates instead of quaternions
 
ChMatrixQc
 {Qc}, the known part, {Qc}=-{C_dtdt}-([Cq]{q_dt})q-2[Cq_dt]{q_dt}
 
ChMatrixCt
 partial derivative of the link kin. equation wrt to time
 
ChMatrixreact
 {l}, the lagrangians forces in the constraints
 
- Protected Attributes inherited from chrono::ChPhysicsItem
ChSystemsystem
 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
 

Member Function Documentation

void chrono::ChLinkMasked::ArchiveIN ( ChArchiveIn marchive)
overridevirtual

Method to allow deserialization of transient data from archives.

Method to allow de serialization of transient data from archives.

Reimplemented from chrono::ChLinkMarkers.

Reimplemented in chrono::ChLinkLock, chrono::ChLinkEngine, chrono::ChLinkPulley, chrono::ChLinkGear, chrono::ChLinkPneumaticActuator, chrono::ChLinkClearance, chrono::ChLinkLinActuator, chrono::ChLinkTrajectory, chrono::ChLinkBrake, chrono::ChLinkBushing, chrono::ChLinkPointSpline, and chrono::ChLinkScrew.

void chrono::ChLinkMasked::ChangedLinkMask ( )

Must be called after whatever change the mask of the link, in order to update auxiliary matrices sizes...

void chrono::ChLinkMasked::ChangeLinkMask ( ChLinkMask new_mask)

Must be called after whatever change the mask of the link, in order to update auxiliary matrices sizes...

void chrono::ChLinkMasked::ConstraintsFetch_react ( double  factor = 1)
overridevirtual

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.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

virtual int chrono::ChLinkMasked::GetDOC_c ( )
overridevirtual

Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this.

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkEngine.

virtual int chrono::ChLinkMasked::GetDOC_d ( )
overridevirtual

Get the number of scalar constraints, if any, in this item (only unilateral constr.) Children classes might override this.

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock.

ChLinkMask* chrono::ChLinkMasked::GetMask ( )

Get the pointer to the link mask, ie.

a ChLinkMask (sort of array containing a set of ChConstraint items).

void chrono::ChLinkMasked::InjectConstraints ( ChSystemDescriptor mdescriptor)
overridevirtual

Tell to a system descriptor that there are contraints of type ChConstraint in this object (for further passing it to a solver) Basically does nothing, but maybe that inherited classes may specialize this.

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

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

After a solver solution, fetch values from variables and constraints: To a vector v from the q 'unknowns' term of the variables To a vector L from the L 'lagrangian ' term of the constraints.

Parameters
off_voffset in v
off_Loffset in L

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

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

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

Parameters
offoffset in Qc residual
Qcresult: the Qc residual, Qc += c*C
ca scaling factor
do_clampapply clamping to c*C?
recovery_clampvalue for min/max clamping of c*C

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

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

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

Parameters
offoffset in Qc residual
Qcresult: the Qc residual, Qc += c*Ct
ca scaling factor

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

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

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

Parameters
off_Loffset in L multipliers
Rresult: the R residual, R += c*Cq'*L
Lthe L vector
ca scaling factor

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

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

Prepare variables and constraints for a solution: From a vector R into the F 'force' term of the variables From a vector Qc into the Qb 'constraint' term of the constraints From a vector v into the q 'unknowns' term of the variables (for warm starting) From a vector L into the L 'lagrangian ' term of the constraints (for warm starting)

Parameters
off_voffset in v, R
off_Loffset in L, Qc

Reimplemented from chrono::ChPhysicsItem.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkEngine.

int chrono::ChLinkMasked::RestoreRedundant ( )
overridevirtual

If some constraint is redundant, return to normal state.

Returns
number of changed states

Reimplemented from chrono::ChLink.

void chrono::ChLinkMasked::SetDisabled ( bool  mdis)
overridevirtual

User can use this to enable/disable all the constraint of the link as desired.

Reimplemented from chrono::ChLinkBase.

Reimplemented in chrono::ChLinkBrake.

void chrono::ChLinkMasked::Update ( double  mytime,
bool  update_assets = true 
)
overridevirtual

This following "complete" update functions actually fill all the matrices of the link, and does all calculus, by calling all the previous Update functions in sequence.

Reimplemented from chrono::ChLinkMarkers.

void chrono::ChLinkMasked::UpdateCqw ( )
virtual

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.

void chrono::ChLinkMasked::UpdateForces ( double  mytime)
overridevirtual

Inherits, and updates the C_force and C_torque 'intuitive' forces, adding the effects of the contained ChLinkForce objects.

(Default: inherits parent UpdateForces(), then C_force and C_torque are incremented with the Link::ChLinkForces objects)

Reimplemented from chrono::ChLinkMarkers.

Reimplemented in chrono::ChLinkLock, chrono::ChLinkEngine, chrono::ChLinkPneumaticActuator, chrono::ChLinkBrake, and chrono::ChLinkClearance.

virtual void chrono::ChLinkMasked::UpdateState ( )
virtual

This is expected to update the values in C, C_dt, C_dtdt, in jacobians Cq1 and Cq2, in Qc and in Ct.

By default, this does NOTHING, so it is up to the inherited classes to fill these vectors/matrices depending on how they describe the constraint equations.

Reimplemented in chrono::ChLinkLock, and chrono::ChLinkScrew.