Description

Motor to enforce the relative position r(t) between two shafts, using a rheonomic constraint.

The position of shaft A with respect to shaft B is set trhough a function of time f(t) and an optional offset: r(t) = f(t) + offset The relative position represents an angle for rotational motor and a displacement for linear motors. Note: no compliance is allowed, so if the actuator hits an undeformable obstacle it hits a pathological situation and the solver result can be unstable/unpredictable. Think at it as a servo drive with "infinitely stiff" control. This type of motor is very easy to use, stable and efficient and should be used if the 'infinitely stiff' control assumption is a good approximation of what you simulate (e.g., very good and reactive controllers). By default it is initialized with linear ramp: df/dt = 1. Use SetPositionFunction() to change to other motion functions.

#include <ChShaftsMotorPosition.h>

Inheritance diagram for chrono::ChShaftsMotorPosition:

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Collaboration diagram for chrono::ChShaftsMotorPosition:

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Public Member Functions
	ChShaftsMotorPosition (const ChShaftsMotorPosition &other)

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

void	SetPositionFunction (const std::shared_ptr< ChFunction > function)
	Set the motor function, f(t). More...

std::shared_ptr< ChFunction >	GetPositionFunction () const
	Gets the motor function f(t).

void	SetOffset (double offset)
	Set the initial offset for f(t)=0 (default: 0). More...

double	GetOffset () const
	Get the initial offset for f(t) = 0.

bool	Initialize (std::shared_ptr< ChShaft > shaft_1, std::shared_ptr< ChShaft > shaft_2) override
	Initialize the motor, given two shafts to join. More...

virtual double	GetMotorLoad () const override
	Get the current motor load between shaft2 and shaft1, expressed as applied to shaft1.

double	GetConstraintViolation () const
	Return current constraint violation.

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

virtual void	ArchiveIn (ChArchiveIn &archive_in) override
	Method to allow deserialization of transient data from archives. More...

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

virtual double	GetMotorPos () const
	Get the position of the motor, as position of shaft 1 with respect to 2. More...

virtual double	GetMotorPosDt () const
	Get the motor speed, as speed of shaft 1 with respect to 2.

virtual double	GetMotorPosDt2 () const
	Get the motor acceleration, as accelerations of shaft 1 with respect to 2.

virtual int	GetMotorNumTurns () const
	Get number of full rotations for this shafts rotational motor. More...

virtual double	GetMotorAngleWrapped () const
	Get the motor angle in the range [-pi, +pi]. More...

virtual double	GetReaction1 () const override
	Get the reaction torque exchanged between the two shafts, considered as applied to the 1st axis.

virtual double	GetReaction2 () const override
	Get the reaction torque exchanged between the two shafts, considered as applied to the 2nd axis.

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

virtual unsigned int	GetNumAffectedCoords ()
	Get the number of scalar variables affected by constraints in this couple.

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

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

double	GetRelativePos () const
	Get the actual relative position (angle or displacement) in terms of phase of shaft 1 with respect to 2.

double	GetRelativePosDt () const
	Get the actual relative speed (angle or displacement) of shaft 1 with respect to 2.

double	GetRelativePosDt2 () const
	Get the actual relative acceleration (angle or displacement) of shaft 1 with 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) const
	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	IsCollisionEnabled () const
	Tell if the object is subject to collision. More...

virtual void	AddCollisionModelsToSystem (ChCollisionSystem *coll_sys) const
	Add to the provided collision system any collision models managed by this physics item. More...

virtual void	RemoveCollisionModelsFromSystem (ChCollisionSystem *coll_sys) const
	Remove from the provided collision system any collision models managed by this physics item. More...

virtual void	SyncCollisionModels ()
	Synchronize the position and bounding box of any collsion models managed by this physics item.

virtual ChAABB	GetTotalAABB ()
	Get the entire AABB axis-aligned bounding box of the object. More...

virtual void	GetCenter (ChVector3d &mcenter)
	Get a symbolic 'center' of the object. 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	Update (bool update_assets=true)
	As above, but does not require updating of time-dependent data. More...

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

virtual unsigned int	GetNumCoordsPosLevel ()
	Get the number of coordinates at the position level. More...

virtual unsigned int	GetNumCoordsVelLevel ()
	Get the number of coordinates at the velocity level. More...

virtual unsigned int	GetNumConstraints ()
	Get the number of scalar constraints.

virtual unsigned int	GetNumConstraintsUnilateral ()
	Get the number of unilateral scalar constraints.

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	IntLoadLumpedMass_Md (const unsigned int off, ChVectorDynamic<> &Md, double &err, const double c)
	Adds the lumped mass to a Md vector, representing a mass diagonal matrix. More...

virtual void	InjectVariables (ChSystemDescriptor &descriptor)
	Register with the given system descriptor any ChVariable objects associated with this item.

virtual void	InjectKRMMatrices (ChSystemDescriptor &descriptor)
	Register with the given system descriptor any ChKRMBlock objects associated with this item.

virtual void	LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor)
	Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. 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	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.

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

int	GetIdentifier () const
	Get the unique integer identifier of this object. More...

void	SetTag (int tag)
	Set an object integer tag (default: -1). More...

int	GetTag () const
	Get the tag of this object.

void	SetName (const std::string &myname)
	Set the name of this object.

const std::string &	GetName () const
	Get the name of this object.

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

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

virtual std::string &	ArchiveContainerName ()

Additional Inherited Members
Protected Member Functions inherited from chrono::ChObj
int	GenerateUniqueIdentifier ()

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
	object simulation time

std::string	m_name
	object name

int	m_identifier
	object unique identifier

int	m_tag
	user-supplied tag

Member Function Documentation

◆ ArchiveIn()

void chrono::ChShaftsMotorPosition::ArchiveIn ( ChArchiveIn & archive_in )

overridevirtual

Method to allow deserialization of transient data from archives.

Method to allow de serialization of transient data from archives.

Reimplemented from chrono::ChShaftsMotor.

◆ Initialize()

bool chrono::ChShaftsMotorPosition::Initialize	(	std::shared_ptr< ChShaft >	shaft_1,
		std::shared_ptr< ChShaft >	shaft_2
	)

overridevirtual

Initialize the motor, given two shafts to join.

The first shaft is the 'output' shaft of the motor, the second is the 'truss', often fixed and not moving. The load is applied to the output shaft, while the truss shafts gets the same load but with opposite sign. Both shafts must belong to the same ChSystem.

Parameters

shaft_1	first shaft to join (motor output shaft)
shaft_2	second shaft to join (motor truss)

Reimplemented from chrono::ChShaftsCouple.

◆ SetOffset()

void chrono::ChShaftsMotorPosition::SetOffset ( double offset )

inline

Set the initial offset for f(t)=0 (default: 0).

Relative position of the two shafts will be r(t) = f(t) + offset.

◆ SetPositionFunction()

void chrono::ChShaftsMotorPosition::SetPositionFunction ( const std::shared_ptr< ChFunction > function )

inline

Set the motor function, f(t).

This function outputs an angle for a rotational motor and a displacement for a linear motor. Note that is must be at least C0 continuous. Ideally, f is C1, otherwise it produces spikes in accelerations.

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

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