Description

Class for defining a 'freewheel' (a 1D model of a ratchet wheel or a sprag-clutch) between two one-degree-of-freedom parts; i.e., shafts that can be used to build 1D models of powertrains.

This is more efficient than simulating power trains modeled with full 3D ChBody objects.

#include <ChShaftsFreewheel.h>

Inheritance diagram for chrono::ChShaftsFreewheel:

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Collaboration diagram for chrono::ChShaftsFreewheel:

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Public Member Functions
	ChShaftsFreewheel ()
	By default this is a ratcheting clutch with 24 teeth: use SetRatchetingModeTeeth() or SetRatchetingModeStep() or SetJammingMode() to change this.

	ChShaftsFreewheel (const ChShaftsFreewheel &other)

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

virtual int	GetDOC_c () override
	Number of scalar constraints.

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

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

bool	Initialize (std::shared_ptr< ChShaft > mshaft1, std::shared_ptr< ChShaft > mshaft2) override
	Use this function after gear creation, to initialize it, given two shafts to join. More...

void	SetRatchetingModeStep (double mt)
	Set if you want the clutch to work in "ratcheting mode", here defined via an angular step in [rad]. More...

void	SetRatchetingModeTeeth (int n_teeth)
	Set if you want the clutch to work in "ratcheting mode", here defined via a number of teeth. More...

void	SetJammingMode ()
	Set if you want the clutch to work in "jamming mode" like a sprag clutch, based on friction with pawls and jamming. More...

double	GetRatchetingStep () const
	Get the angular step [rad], if a "ratcheting mode" freewheel (it is zero if in "jamming mode").

bool	IsModeJamming ()
	True if the clutch is working in "jamming mode" like a sprag clutch, hence a perfect unidirectional clutch without backward backlash.

bool	IsModeRatcheting ()
	True if the clutch is working in "ratcheting mode", hence with some periodic backward backlash.

void	SetFreeForward ()
	Shaft 1 free to rotate forward respect to shaft 2. More...

void	SetFreeBackward ()
	Shaft 1 free to rotate backward respect to shaft 2. More...

bool	IsFreeForward ()
	If true, shaft 1 is free to rotate forward respect to shaft 2 (default). More...

void	SetPhase (double mp)
	If in "ratcheting mode", this is the phase of the first tooth respect to zero rotation of shaft 1. Default 0.

double	GetPhase ()
	If in "ratcheting mode", this is the phase of the first tooth respect to zero rotation of shaft 1.

double	GetTorqueReactionOn1 () const override
	Get the reaction torque exchanged between the two shafts, considered as applied to the 1st axis.

double	GetTorqueReactionOn2 () const override
	Get the reaction torque exchanged between the two shafts, considered as applied to the 2nd axis.

double	GetConstraintViolation () const
	Return current constraint violation.

double	GetMaxReachedRelativeRotation () const
	Return current max relative rotation.

double	GetCurrentTeethVane () const
	Return the current teeth vane in ratcheting freewheel (returns zero if in jamming mode).

virtual void	Update (double mytime, bool update_assets=true) override
	Update all auxiliary data of the gear transmission at given time.

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::ChShaftsCouple
	ChShaftsCouple (const ChShaftsCouple &other)

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

ChShaft *	GetShaft1 ()
	Get the first (input) shaft.

ChShaft *	GetShaft2 ()
	Get the second (output) shaft.

double	GetRelativeRotation () const
	Get the actual relative angle in terms of phase of shaft 1 respect to 2.

double	GetRelativeRotation_dt () const
	Get the actual relative speed in terms of speed of shaft 1 respect to 2.

double	GetRelativeRotation_dtdt () const
	Get the actual relative acceleration in terms of speed of shaft 1 respect to 2.

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 ChFrame	GetVisualModelFrame (unsigned int nclone=0)
	Get the reference frame (expressed in and relative to the absolute frame) of the visual model. 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	IsActive () const
	Return true if the object is active and included in dynamics.

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	Update (bool update_assets=true)
	As above, but does not require updating of time-dependent data. More...

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...

virtual int	GetDOC ()
	Get the number of scalar constraints, if any, in this item.

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

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	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	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	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.

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 ()

Additional Inherited Members
Protected Attributes inherited from chrono::ChShaftsCouple
ChShaft *	shaft1
	first shaft

ChShaft *	shaft2
	second shaft

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
	the time of simulation for the object

Member Function Documentation

◆ ArchiveIN()

void chrono::ChShaftsFreewheel::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::ChShaftsCouple.

◆ ConstraintsFetch_react()

void chrono::ChShaftsFreewheel::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.

◆ Initialize()

bool chrono::ChShaftsFreewheel::Initialize	(	std::shared_ptr< ChShaft >	mshaft1,
		std::shared_ptr< ChShaft >	mshaft2
	)

overridevirtual

Use this function after gear creation, to initialize it, given two shafts to join.

Each shaft must belong to the same ChSystem. By default this is a ratcheting clutch with 24 teeth: use SetRatchetingModeTeeth() or SetRatchetingModeStep() or SetJammingMode() to change this.

Parameters

mshaft1	first shaft to join
mshaft2	second shaft to join

Reimplemented from chrono::ChShaftsCouple.

◆ IntFromDescriptor()

void chrono::ChShaftsFreewheel::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 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::ChShaftsFreewheel::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

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.

◆ IntLoadResidual_CqL()

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

overridevirtual

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::ChShaftsFreewheel::IntStateScatterReactions	(	const unsigned int	off_L,
		const ChVectorDynamic<> &	L
	)

overridevirtual

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::ChShaftsFreewheel::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 to accommodate a solution:

Parameters

off_v	offset for v and R
v	vector copied into the q 'unknowns' term of the variables
R	vector copied into the F 'force' term of the variables
off_L	offset for L and Qc
L	vector copied into the L 'lagrangian ' term of the constraints
Qc	vector copied into the Qb 'constraint' term of the constraints

Reimplemented from chrono::ChPhysicsItem.

◆ IsFreeForward()

bool chrono::ChShaftsFreewheel::IsFreeForward ( )

inline

If true, shaft 1 is free to rotate forward respect to shaft 2 (default).

Viceversa, if false. Use SetFreeForward() or SetFreeBackward() to change this mode.

◆ SetFreeBackward()

void chrono::ChShaftsFreewheel::SetFreeBackward ( )

inline

Shaft 1 free to rotate backward respect to shaft 2.

Viceversa, forward rotation of 1 respect to 2 is prevented and will generate a torque.

◆ SetFreeForward()

void chrono::ChShaftsFreewheel::SetFreeForward ( )

inline

Shaft 1 free to rotate forward respect to shaft 2.

Viceversa, backward rotation of 1 respect to 2 is prevented and will generate a torque.

◆ SetJammingMode()

void chrono::ChShaftsFreewheel::SetJammingMode ( )

inline

Set if you want the clutch to work in "jamming mode" like a sprag clutch, based on friction with pawls and jamming.

This is like a ratcheting clutch with infinite teeth, hence a perfect unidirectional clutch without backward backlash, but instead of using SetRatchetingModeStep(0), that can't work well because of bad conditioning, just use this.

◆ SetRatchetingModeStep()

void chrono::ChShaftsFreewheel::SetRatchetingModeStep ( double mt )

inline

Set if you want the clutch to work in "ratcheting mode", here defined via an angular step in [rad].

When in ratcheting mode, there is a periodic "backward backlash", like in bicycle freewheels.

◆ SetRatchetingModeTeeth()

void chrono::ChShaftsFreewheel::SetRatchetingModeTeeth ( int n_teeth )

inline

Set if you want the clutch to work in "ratcheting mode", here defined via a number of teeth.

When in ratcheting mode, there is a periodic "backward backlash", like in bicycle freewheels.

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

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

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ArchiveIN()

◆ ConstraintsFetch_react()

◆ Initialize()

◆ IntFromDescriptor()

◆ IntLoadConstraint_C()

◆ IntLoadResidual_CqL()

◆ IntStateGatherReactions()

◆ IntStateScatterReactions()

◆ IntToDescriptor()

◆ IsFreeForward()

◆ SetFreeBackward()

◆ SetFreeForward()

◆ SetJammingMode()

◆ SetRatchetingModeStep()

◆ SetRatchetingModeTeeth()