Description

Class for one-degree-of-freedom mechanical parts with associated inertia (mass, or J moment of inertial for rotating parts).

In most cases these represent shafts that can be used to build 1D models of power trains. This is more efficient than simulating power trains modeled with full 3D ChBody objects.

#include <ChShaft.h>

Inheritance diagram for chrono::ChShaft:

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Collaboration diagram for chrono::ChShaft:

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Public Member Functions
	ChShaft (const ChShaft &other)

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

void	SetShaftFixed (bool mev)
	Sets the 'fixed' state of the shaft. More...

bool	GetShaftFixed () const

void	SetLimitSpeed (bool mlimit)
	Trick. More...

bool	GetLimitSpeed () const

void	SetUseSleeping (bool ms)
	Trick. More...

bool	GetUseSleeping () const

void	SetSleeping (bool ms)
	Force the shaft in sleeping mode or not (usually this state change is not handled by users, anyway, because it is mostly automatic).

bool	GetSleeping () const
	Tell if the shaft is actually in sleeping state.

bool	TrySleeping ()
	Put the shaft in sleeping state if requirements are satisfied.

bool	IsActive () const
	Tell if the body is active, i.e. More...

void	SetId (unsigned int identifier)
	Set the shaft id for indexing (only used internally)

unsigned int	GetId () const
	Get the shaft id for indexing (only used internally)

virtual int	GetDOF () override
	Number of coordinates of the shaft.

ChVariablesShaft &	Variables ()
	Returns reference to the encapsulated ChVariables,.

virtual void	IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T) override
	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) override
	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) override
	From item's state acceleration to global acceleration vector. More...

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

virtual void	IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
	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) override
	Takes the Mv term, multiplying mass by a vector, scale and adds to R at given offset: R += cM*w. 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	VariablesFbReset () override
	Sets the 'fb' part of the encapsulated ChVariables to zero.

virtual void	VariablesFbLoadForces (double factor=1) override
	Adds the current torques in the 'fb' part: qf+=torques*factor.

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

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

virtual void	VariablesQbSetSpeed (double step=0) override
	Fetches the shaft speed from the 'qb' part of the ChVariables (does not updates the full shaft state) and sets it as the current shaft speed. More...

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

virtual void	InjectVariables (ChSystemDescriptor &mdescriptor) override
	Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver)

virtual int	LoadableGet_ndof_x () override
	Gets the number of DOFs affected by this element (position part)

virtual int	LoadableGet_ndof_w () override
	Gets the number of DOFs affected by this element (speed part)

virtual void	LoadableGetStateBlock_x (int block_offset, ChState &mD) override
	Gets all the DOFs packed in a single vector (position part)

virtual void	LoadableGetStateBlock_w (int block_offset, ChStateDelta &mD) override
	Gets all the DOFs packed in a single vector (speed part)

virtual void	LoadableStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv) override
	Increment all DOFs using a delta. More...

virtual int	Get_field_ncoords () override
	Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc.

virtual int	GetSubBlocks () override
	Tell the number of DOFs blocks (ex. =1 for a body, =4 for a tetrahedron, etc.)

virtual unsigned int	GetSubBlockOffset (int nblock) override
	Get the offset of the i-th sub-block of DOFs in global vector.

virtual unsigned int	GetSubBlockSize (int nblock) override
	Get the size of the i-th sub-block of DOFs in global vector.

virtual void	LoadableGetVariables (std::vector< ChVariables * > &mvars) override
	Get the pointers to the contained ChVariables, appending to the mvars vector.

void	SetNoSpeedNoAcceleration () override
	Set no speed and no accelerations (but does not change the position)

void	SetAppliedTorque (double mtorque)
	Set the torque applied to the shaft.

double	GetAppliedTorque () const
	Get the torque applied to the shaft.

void	SetPos (double mp)
	Set the angular position.

double	GetPos () const
	Get the angular position.

void	SetPos_dt (double mp)
	Set the angular velocity.

double	GetPos_dt () const
	Get the angular velocity.

void	SetPos_dtdt (double mp)
	Set the angular acceleration.

double	GetPos_dtdt () const
	Get the angular acceleration.

void	SetInertia (double newJ)
	Inertia of the shaft. More...

double	GetInertia () const

void	SetMaxSpeed (float m_max_speed)
	Trick. More...

float	GetMaxSpeed () const

void	ClampSpeed ()
	When this function is called, the speed of the shaft is clamped into limits posed by max_speed and max_wvel - but remember to put the shaft in the SetLimitSpeed(true) mode.

void	SetSleepTime (float m_t)
	Set the amount of time which must pass before going automatically in sleep mode when the shaft has very small movements.

float	GetSleepTime () const

void	SetSleepMinSpeed (float m_t)
	Set the max linear speed to be kept for 'sleep_time' before freezing.

float	GetSleepMinSpeed () const

void	SetSleepMinWvel (float m_t)
	Set the max linear speed to be kept for 'sleep_time' before freezing.

float	GetSleepMinWvel () const

virtual void	Update (double mytime, bool update_assets=true) override
	Update all auxiliary data of the shaft 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::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 ChFrame	GetAssetsFrame (unsigned int nclone=0)
	Get the master coordinate system for assets that have some geometric meaning. More...

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	Update (bool update_assets=true)
	As above, but does not require updating of time-dependent data. 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_c ()
	Get the number of scalar constraints, if any, in this item (only bilateral constr.) Children classes might override this.

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

virtual void	IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L)
	From global reaction vector to item's reaction forces. 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_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c)
	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)
	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)
	Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...

virtual void	InjectConstraints (ChSystemDescriptor &mdescriptor)
	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 ()
	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)
	Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.

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	ConstraintsLoadJacobians ()
	Adds the current jacobians in encapsulated ChConstraints.

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

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::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

Member Function Documentation

◆ ArchiveIN()

void chrono::ChShaft::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::ChPhysicsItem.

◆ IntFromDescriptor()

void chrono::ChShaft::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.

◆ IntLoadResidual_F()

void chrono::ChShaft::IntLoadResidual_F	(	const unsigned int	off,
		ChVectorDynamic<> &	R,
		const double	c
	)

overridevirtual

Takes the F force term, scale and adds to R at given offset: R += c*F.

Parameters

off	offset in R residual
R	result: the R residual, R += c*F
c	a scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntLoadResidual_Mv()

void chrono::ChShaft::IntLoadResidual_Mv	(	const unsigned int	off,
		ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	w,
		const double	c
	)

overridevirtual

Takes the M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*w.

Parameters

off	offset in R residual
R	result: the R residual, R += cMv
w	the w vector
c	a scaling factor

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateGather()

void chrono::ChShaft::IntStateGather	(	const unsigned int	off_x,
		ChState &	x,
		const unsigned int	off_v,
		ChStateDelta &	v,
		double &	T
	)

overridevirtual

From item's state to global state vectors y={x,v} pasting the states at the specified offsets.

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateGatherAcceleration()

void chrono::ChShaft::IntStateGatherAcceleration	(	const unsigned int	off_a,
		ChStateDelta &	a
	)

overridevirtual

From item's state acceleration to global acceleration vector.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateScatter()

void chrono::ChShaft::IntStateScatter	(	const unsigned int	off_x,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	v,
		const double	T
	)

overridevirtual

From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets.

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time

Reimplemented from chrono::ChPhysicsItem.

◆ IntStateScatterAcceleration()

void chrono::ChShaft::IntStateScatterAcceleration	(	const unsigned int	off_a,
		const ChStateDelta &	a
	)

overridevirtual

From global acceleration vector to item's state acceleration.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChPhysicsItem.

◆ IntToDescriptor()

void chrono::ChShaft::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 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.

◆ IsActive()

bool chrono::ChShaft::IsActive ( ) const

inline

Tell if the body is active, i.e.

it is neither fixed to ground nor it is in sleep mode.

◆ LoadableStateIncrement()

virtual void chrono::ChShaft::LoadableStateIncrement	(	const unsigned int	off_x,
		ChState &	x_new,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	Dv
	)

inlineoverridevirtual

Increment all DOFs using a delta.

Default is sum, but may override if ndof_x is different than ndof_w, for example with rotation quaternions and angular w vel. This could be invoked, for example, by the BDF differentiation that computes the jacobians.

Implements chrono::ChLoadable.

◆ SetInertia()

void chrono::ChShaft::SetInertia ( double newJ )

Inertia of the shaft.

Must be positive. Try not to mix bodies with too high/too low values of mass, for numerical stability.

◆ SetLimitSpeed()

void chrono::ChShaft::SetLimitSpeed ( bool mlimit )

inline

Trick.

Set the maximum shaft velocity (beyond this limit it will be clamped). This is useful in virtual reality and real-time simulations. The realism is limited, but the simulation is more stable.

◆ SetMaxSpeed()

void chrono::ChShaft::SetMaxSpeed ( float m_max_speed )

inline

Trick.

Set the maximum velocity (beyond this limit it will be clamped). This is useful in virtual reality and real-time simulations, to increase robustness at the cost of realism. This limit is active only if you set SetLimitSpeed(true);

◆ SetShaftFixed()

void chrono::ChShaft::SetShaftFixed ( bool mev )

inline

Sets the 'fixed' state of the shaft.

If true, it does not rotate despite constraints, forces, etc.

◆ SetUseSleeping()

void chrono::ChShaft::SetUseSleeping ( bool ms )

inline

Trick.

If use sleeping= true, shafts which do not rotate for too long time will be deactivated, for optimization. The realism is limited, but the simulation is faster.

◆ VariablesFbIncrementMq()

void chrono::ChShaft::VariablesFbIncrementMq ( )

overridevirtual

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

if qb is initialized with v_old using VariablesQbLoadSpeed, this method can be used in timestepping schemes that do: M*v_new = M*v_old + forces*dt

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbIncrementPosition()

void chrono::ChShaft::VariablesQbIncrementPosition ( double step )

overridevirtual

Increment shaft position by the 'qb' part of the ChVariables, multiplied by a 'step' factor.

pos+=qb*step

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbLoadSpeed()

void chrono::ChShaft::VariablesQbLoadSpeed ( )

overridevirtual

Initialize the 'qb' part of the ChVariables with the current value of shaft speed.

Note: since 'qb' is the unknown , this function seems unnecessary, unless used before VariablesFbIncrementMq()

Reimplemented from chrono::ChPhysicsItem.

◆ VariablesQbSetSpeed()

void chrono::ChShaft::VariablesQbSetSpeed ( double step = 0 )

overridevirtual

Fetches the shaft speed from the 'qb' part of the ChVariables (does not updates the full shaft state) and sets it as the current shaft speed.

If 'step' is not 0, also computes the approximate acceleration of the shaft using backward differences, that is accel=(new_speed-old_speed)/step.

Reimplemented from chrono::ChPhysicsItem.

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

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

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ArchiveIN()

◆ IntFromDescriptor()

◆ IntLoadResidual_F()

◆ IntLoadResidual_Mv()

◆ IntStateGather()

◆ IntStateGatherAcceleration()

◆ IntStateScatter()

◆ IntStateScatterAcceleration()

◆ IntToDescriptor()

◆ IsActive()

◆ LoadableStateIncrement()

◆ SetInertia()

◆ SetLimitSpeed()

◆ SetMaxSpeed()

◆ SetShaftFixed()

◆ SetUseSleeping()

◆ VariablesFbIncrementMq()

◆ VariablesQbIncrementPosition()

◆ VariablesQbLoadSpeed()

◆ VariablesQbSetSpeed()