Description

This class implements the functionality for a constraint between a couple of two objects of type ChVariablesBody.

#include <ChConstraintTwoBodies.h>

Inheritance diagram for chrono::ChConstraintTwoBodies:

Collaboration diagram for chrono::ChConstraintTwoBodies:

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Public Member Functions
	ChConstraintTwoBodies ()
	Default constructor.

	ChConstraintTwoBodies (ChVariablesBody mvariables_a, ChVariablesBody mvariables_b)
	Construct and immediately set references to variables.

	ChConstraintTwoBodies (const ChConstraintTwoBodies &other)
	Copy constructor.

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

ChConstraintTwoBodies &	operator= (const ChConstraintTwoBodies &other)
	Assignment operator: copy from other object.

virtual ChRowVectorRef	Get_Cq_a () override
	Access jacobian vector.

virtual ChRowVectorRef	Get_Cq_b () override
	Access jacobian vector.

virtual ChVectorRef	Get_Eq_a () override
	Access auxiliary vector (ex: used by iterative solvers).

virtual ChVectorRef	Get_Eq_b () override
	Access auxiliary vector (ex: used by iterative solvers).

void	SetVariables (ChVariables mvariables_a, ChVariables mvariables_b) override
	Set references to the constrained objects, each of ChVariablesBody type, automatically creating/resizing jacobians if needed. More...

virtual void	Update_auxiliary () override
	This function updates the following auxiliary data: More...

virtual double	Compute_Cq_q () override
	This function must computes the product between the row-jacobian of this constraint '[Cq_i]' and the vector of variables 'v', that is CV=[Cq_i]*v. More...

virtual void	Increment_q (const double deltal) override
	This function must increment the vector of variables 'v' with the quantity [invM][Cq_i]'deltal, that is v+=[invM][Cq_i]'deltal or better: v+=[Eq_i]*deltal. More...

virtual void	MultiplyAndAdd (double &result, const ChVectorDynamic< double > &vect) const override
	Computes the product of the corresponding block in the system matrix by 'vect', and add to 'result'. More...

virtual void	MultiplyTandAdd (ChVectorDynamic< double > &result, double l) override
	Computes the product of the corresponding transposed blocks in the system matrix (ie. More...

virtual void	Build_Cq (ChSparseMatrix &storage, int insrow) override
	Puts the two jacobian parts into the 'insrow' row of a sparse matrix, where both portions of the jacobian are shifted in order to match the offset of the corresponding ChVariable.The same is done on the 'insrow' column, so that the sparse matrix is kept symmetric.

virtual void	Build_CqT (ChSparseMatrix &storage, int inscol) override
	Same as Build_Cq, but puts the transposed jacobian row as a column.

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

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

Public Member Functions inherited from chrono::ChConstraintTwo
	ChConstraintTwo ()
	Default constructor.

	ChConstraintTwo (const ChConstraintTwo &other)
	Copy constructor.

ChConstraintTwo &	operator= (const ChConstraintTwo &other)
	Assignment operator: copy from other object.

ChVariables *	GetVariables_a ()
	Access the first variable object.

ChVariables *	GetVariables_b ()
	Access the second variable object.

Public Member Functions inherited from chrono::ChConstraint
	ChConstraint ()
	Default constructor.

	ChConstraint (const ChConstraint &other)
	Copy constructor.

ChConstraint &	operator= (const ChConstraint &other)
	Assignment operator: copy from other object.

bool	operator== (const ChConstraint &other) const
	Comparison (compares only flags, not the jacobians etc.)

bool	IsValid () const
	Tells if the constraint data is currently valid.

void	SetValid (bool mon)
	Use this function to set the valid state (child class Children classes must use this function depending on the result of their implementations of RestoreReference();.

bool	IsDisabled () const
	Tells if the constraint is currently turned on or off by the user.

void	SetDisabled (bool mon)
	User can use this to enable/disable the constraint as desired.

bool	IsRedundant () const
	Tells if the constraint is redundant or singular.

void	SetRedundant (bool mon)
	Solvers may use the following to mark a constraint as redundant.

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

void	SetBroken (bool mon)
	3rd party software can set the 'broken' status via this method (by default, constraints never break);

virtual bool	IsUnilateral () const
	Tells if the constraint is unilateral (typical complementarity constraint).

virtual bool	IsLinear () const
	Tells if the constraint is linear (if non linear, returns false).

eChConstraintMode	GetMode () const
	Gets the mode of the constraint: free / lock / complementary A typical constraint has 'lock = true' by default.

void	SetMode (eChConstraintMode mmode)
	Sets the mode of the constraint: free / lock / complementary.

bool	IsActive () const
	Tells if the constraint is currently active, in general, that is tells if it must be included into the system solver or not. More...

void	SetActive (bool isactive)
	Set the status of the constraint to active.

virtual double	Compute_c_i ()
	Compute the residual of the constraint using the LINEAR expression. More...

double	Get_c_i () const
	Return the residual 'c_i' of this constraint. // CURRENTLY NOT USED.

void	Set_b_i (const double mb)
	Sets the known term b_i in [Cq_i]q + b_i = 0, where: c_i = [Cq_i]q + b_i = 0.

double	Get_b_i () const
	Return the known term b_i in [Cq_i]q + b_i = 0, where: c_i= [Cq_i]q + b_i = 0.

void	Set_cfm_i (const double mcfm)
	Sets the constraint force mixing term (default=0). More...

double	Get_cfm_i () const
	Returns the constraint force mixing term.

void	Set_l_i (double ml_i)
	Sets the 'l_i' value (constraint reaction, see 'l' vector)

double	Get_l_i () const
	Return the 'l_i' value (constraint reaction, see 'l' vector)

double	Get_g_i () const
	Return the 'g_i' product , that is [Cq_i][invM_i][Cq_i]' (+cfm)

void	Set_g_i (double m_g_i)
	Usually you should not use the Set_g_i function, because g_i should be automatically computed during the Update_auxiliary() .

virtual void	Project ()
	For iterative solvers: project the value of a possible 'l_i' value of constraint reaction onto admissible orthant/set. More...

virtual double	Violation (double mc_i)
	Given the residual of the constraint computed as the linear map mc_i = [Cq]q + b_i + cfml_i , returns the violation of the constraint, considering inequalities, etc. More...

void	SetOffset (int moff)
	Set offset in global q vector (set automatically by ChSystemDescriptor)

int	GetOffset () const
	Get offset in global q vector.

Protected Attributes
ChRowVectorN< double, 6 >	Cq_a
	The [Cq_a] jacobian of the constraint.

ChRowVectorN< double, 6 >	Cq_b
	The [Cq_b] jacobian of the constraint.

ChVectorN< double, 6 >	Eq_a
	The [Eq_a] product [Eq_a]=[invM_a]*[Cq_a]'.

ChVectorN< double, 6 >	Eq_b
	The [Eq_a] product [Eq_b]=[invM_b]*[Cq_b]'.

Protected Attributes inherited from chrono::ChConstraintTwo
ChVariables *	variables_a
	The first constrained object.

ChVariables *	variables_b
	The second constrained object.

Protected Attributes inherited from chrono::ChConstraint
double	c_i
	The 'c_i' residual of the constraint (if satisfied, c must be 0)

double	l_i
	The 'l_i' lagrangian multiplier (reaction)

double	b_i
	The 'b_i' right term in [Cq_i]q+b_i=0 , note: c_i= [Cq_i]q + b_i.

double	cfm_i
	The constraint force mixing, if needed (usually is zero) to add some numerical 'compliance' in the constraint, that is the equation becomes: c_i= [Cq_i]q + b_i + cfml_i =0; Example, it could be cfm = [k * h^2](^-1) where k is stiffness.

eChConstraintMode	mode
	mode of the constraint: free / lock / complementar

double	g_i
	'g_i' product [Cq_i][invM_i][Cq_i]' (+cfm)

int	offset
	offset in global "l" state vector (needed by some solvers)

Member Function Documentation

◆ Compute_Cq_q()

double chrono::ChConstraintTwoBodies::Compute_Cq_q ( )

overridevirtual

This function must computes the product between the row-jacobian of this constraint '[Cq_i]' and the vector of variables 'v', that is CV=[Cq_i]*v.

This is used for some iterative solvers.

Implements chrono::ChConstraint.

◆ Increment_q()

void chrono::ChConstraintTwoBodies::Increment_q ( const double deltal )

overridevirtual

This function must increment the vector of variables 'v' with the quantity [invM]*[Cq_i]'deltal, that is v+=[invM][Cq_i]'*deltal or better: v+=[Eq_i]*deltal.

This is used for some iterative solvers.

Implements chrono::ChConstraint.

◆ MultiplyAndAdd()

void chrono::ChConstraintTwoBodies::MultiplyAndAdd	(	double &	result,
		const ChVectorDynamic< double > &	vect
	)		const

overridevirtual

Computes the product of the corresponding block in the system matrix by 'vect', and add to 'result'.

NOTE: the 'vect' vector must already have the size of the total variables&constraints in the system; the procedure will use the ChVariable offsets (that must be already updated) to know the indexes in result and vect;

Implements chrono::ChConstraint.

◆ MultiplyTandAdd()

void chrono::ChConstraintTwoBodies::MultiplyTandAdd	(	ChVectorDynamic< double > &	result,
		double	l
	)

overridevirtual

Computes the product of the corresponding transposed blocks in the system matrix (ie.

the TRANSPOSED jacobian matrix C_q') by 'l', and add to 'result'. NOTE: the 'result' vector must already have the size of the total variables&constraints in the system; the procedure will use the ChVariable offsets (that must be already updated) to know the indexes in result and vect;

Implements chrono::ChConstraint.

◆ SetVariables()

void chrono::ChConstraintTwoBodies::SetVariables	(	ChVariables *	mvariables_a,
		ChVariables *	mvariables_b
	)

overridevirtual

Set references to the constrained objects, each of ChVariablesBody type, automatically creating/resizing jacobians if needed.

If variables are not from ChVariablesBody class, an assert failure happens.

Implements chrono::ChConstraintTwo.

◆ Update_auxiliary()

void chrono::ChConstraintTwoBodies::Update_auxiliary ( )

overridevirtual

This function updates the following auxiliary data:

the Eq_a and Eq_b matrices
the g_i product This is often called by solvers at the beginning of the solution process. Most often, inherited classes won't need to override this.

Reimplemented from chrono::ChConstraint.

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

/builds/uwsbel/chrono/src/chrono/solver/ChConstraintTwoBodies.h
/builds/uwsbel/chrono/src/chrono/solver/ChConstraintTwoBodies.cpp

Description

Public Member Functions

Protected Attributes

Member Function Documentation

◆ Compute_Cq_q()

◆ Increment_q()

◆ MultiplyAndAdd()

◆ MultiplyTandAdd()

◆ SetVariables()

◆ Update_auxiliary()