Description

Base class for a hydraulic actuator.

All hydraulic actuators contain a cylinder and a directional valve. Derived classes may add additional components and combine these in circuits with different numbers of fluid (oil) volumes.

A hydraulic actuator can be attached between two bodies, in which case the actuator length and length rate of change is inferred from the states of those two bodies. Alternatively, a hydraulic actuator can be instantiated stand-alone (e.g., for use in a co-simulation setting), in which case the actuator length and rate must be provided from outside.

#include <ChHydraulicActuator.h>

Inheritance diagram for chrono::ChHydraulicActuatorBase:

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Collaboration diagram for chrono::ChHydraulicActuatorBase:

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Public Member Functions
void	SetInputFunction (std::shared_ptr< ChFunction > fun)
	Set the actuation function. More...

void	SetPressures (double pump_pressure, double tank_pressure)
	Set the tank and pump pressures.

void	SetActuatorInitialLength (double len)
	Set actuator initial length [m]. More...

void	SetInitialLoad (double F0)
	Set initial loading force. More...

void	Initialize ()
	Initialize the hydraulic actuator stand-alone. More...

void	Initialize (std::shared_ptr< ChBody > body1, std::shared_ptr< ChBody > body2, bool local, ChVector3d loc1, ChVector3d loc2)
	Initialize this hydraulic actuator by connecting it between the two specified bodies. More...

ChHydraulicCylinder &	Cylinder ()
	Access the hydraulic cylinder in this circuit.

ChHydraulicDirectionalValve4x3 &	DirectionalValve ()
	Access the directoinal valve in this circuit.

ChVector3d	GetPoint1Abs () const
	Get the endpoint location on 1st body (expressed in absolute coordinate system). More...

ChVector3d	GetPoint2Abs () const
	Get the endpoint location on 2nd body (expressed in body coordinate system). More...

void	SetActuatorLength (double len, double vel)
	Set the current actuator length and rate of change. More...

double	GetActuatorForce ()
	Get the current actuator force. More...

std::array< double, 2 >	GetCylinderPressures ()
	Get the current cylinder pressures.

double	GetValvePosition ()
	Get the current directional valve position.

Public Member Functions inherited from chrono::ChExternalDynamics
virtual ChExternalDynamics *	Clone () const override
	"Virtual" copy constructor (covariant return type).

void	Initialize ()
	Initialize the physics item.

ChVectorDynamic	GetInitialStates ()
	Get the initial values (state at initial time).

const ChVectorDynamic &	GetStates () const
	Get current states.

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

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

virtual unsigned int	GetNumConstraintsBilateral ()
	Get the number of bilateral 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	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	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_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 &descriptor)
	Register with the given system descriptor any ChConstraint objects associated with this item.

virtual void	LoadConstraintJacobians ()
	Compute and load current Jacobians in encapsulated ChConstraint objects.

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

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::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 ()

Protected Member Functions
virtual void	OnInitialize (const Vec2 &cyl_p0, const Vec2 &cyl_L0, double dvalve_U0)=0
	Process initial cylinder pressures and initial valve displacement. More...

virtual double	ExtractValveSpoolPosition () const =0
	Extract directional valve spool position from current state.

virtual Vec2	ExtractCylinderPressures () const =0
	Extract cylinder pressures from current state.

double	GetInput (double t) const
	Get current actuator input.

virtual bool	IsStiff () const override
	Declare the EOM of this physics item as stiff or non-stiff.

virtual void	Update (double time, bool update_assets=true) override
	Update the physics item at current state.

virtual void	IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
	Load generalized forces.

Protected Member Functions inherited from chrono::ChExternalDynamics
virtual unsigned int	GetNumStates () const
	Specify number of states (dimension of y).

virtual void	SetInitialConditions (ChVectorDynamic<> &y0)
	Set initial conditions. More...

virtual void	CalculateRHS (double time, const ChVectorDynamic<> &y, ChVectorDynamic<> &rhs)
	Calculate and return the ODE right-hand side at the provided time and states. More...

virtual bool	CalculateJac (double time, const ChVectorDynamic<> &y, const ChVectorDynamic<> &rhs, ChMatrixDynamic<> &J)
	Calculate the Jacobian of the ODE right-hand side with respect to the ODE states. More...

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

ChVariables &	Variables ()

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

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

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, bool full_update) 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_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &v, 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	IntLoadLumpedMass_Md (const unsigned int off, ChVectorDynamic<> &Md, double &err, const double c) override
	Adds the lumped mass to a Md vector, representing a mass diagonal matrix. 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	LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor) override
	Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. More...

virtual void	VariablesFbReset () override
	Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.

virtual void	VariablesFbLoadForces (double factor=1) override
	Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.

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

virtual void	VariablesQbSetSpeed (double step=0) override
	Fetches the item speed (ex. More...

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

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

virtual void	ConstraintsFbLoadForces (double factor=1) override
	Adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints.

void	ComputeJac (double time)
	Compute the Jacobian at the current time and state.

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

Protected Attributes
bool	is_attached
	true if actuator attached to bodies

ChBody *	m_body1
	first conected body

ChBody *	m_body2
	second connected body

ChVector3d	m_loc1
	point on body 1 (local frame)

ChVector3d	m_loc2
	point on body 2 (local frame)

ChVector3d	m_aloc1
	point on body 1 (global frame)

ChVector3d	m_aloc2
	point on body 2 (global frame)

ChVectorDynamic	m_Qforce
	generalized forcing terms

ChHydraulicCylinder	cyl
	hydraulic cylinder

ChHydraulicDirectionalValve4x3	dvalve
	directional valve

std::shared_ptr< ChFunction >	ref_fun
	actuation function (spool displacement reference)

double	s_0
	initial actuator length [m]

double	s
	current actuator length [m]

double	sd
	current actuator speed [m/s]

double	pP
	pump pressure [Pa]

double	pT
	tank pressure [Pa]

bool	calculate_consistent_IC
	solve initialization nonlinear system

double	F0
	estimated initial load

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

◆ GetActuatorForce()

double chrono::ChHydraulicActuatorBase::GetActuatorForce ( )

Get the current actuator force.

Can be used in a co-simulation interface.

◆ GetPoint1Abs()

ChVector3d chrono::ChHydraulicActuatorBase::GetPoint1Abs ( ) const

inline

Get the endpoint location on 1st body (expressed in absolute coordinate system).

Returns a zero location if the actuator is not attached to bodies.

◆ GetPoint2Abs()

ChVector3d chrono::ChHydraulicActuatorBase::GetPoint2Abs ( ) const

inline

Get the endpoint location on 2nd body (expressed in body coordinate system).

Returns a zero location if the actuator is not attached to bodies.

◆ Initialize() [1/2]

void chrono::ChHydraulicActuatorBase::Initialize ( )

Initialize the hydraulic actuator stand-alone.

In this case, actuator position and rate are supposed to be provided from the outside.

◆ Initialize() [2/2]

void chrono::ChHydraulicActuatorBase::Initialize	(	std::shared_ptr< ChBody >	body1,
		std::shared_ptr< ChBody >	body2,
		bool	local,
		ChVector3d	loc1,
		ChVector3d	loc2
	)

Initialize this hydraulic actuator by connecting it between the two specified bodies.

Parameters

body1	first connected body
body2	second connected body
local	true if locations given in body local frames
loc1	location of connection point on body 1
loc2	location of connection point on body 2

◆ OnInitialize()

virtual void chrono::ChHydraulicActuatorBase::OnInitialize	(	const Vec2 &	cyl_p0,
		const Vec2 &	cyl_L0,
		double	dvalve_U0
	)

protectedpure virtual

Process initial cylinder pressures and initial valve displacement.

Optionally, if the initial load F0 is provided, a derived class may calculate consistent initial conditions using the provided values as an initial guess.

◆ SetActuatorInitialLength()

void chrono::ChHydraulicActuatorBase::SetActuatorInitialLength ( double len )

Set actuator initial length [m].

This value is used only for an actuator not attached to bodies. For a connected actuator, the initial length is inferred from the initial body positions.

◆ SetActuatorLength()

void chrono::ChHydraulicActuatorBase::SetActuatorLength	(	double	len,
		double	vel
	)

Set the current actuator length and rate of change.

Can be used in a co-simulation interface.

◆ SetInitialLoad()

void chrono::ChHydraulicActuatorBase::SetInitialLoad ( double F0 )

Set initial loading force.

If provided, this value is used in calculating consistent initial conditions, using the initial dircetional valve spool position and the initial cylinder pressures as initial guesses. Otherwise, the initial actuator state is set to the user specified values (which may be inconsistent with the configuration of the cylinder piston).

◆ SetInputFunction()

void chrono::ChHydraulicActuatorBase::SetInputFunction ( std::shared_ptr< ChFunction > fun )

inline

Set the actuation function.

This function should return the directional valve input, normalized to the interval [-1,1]. The extreme values correspond to the maximum input voltage (providing full opening of the valve) to the proportional magnet controlling the valve spool position. Note that the provided input is automatically clamped to [-1,1].

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

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

Description

Public Member Functions

Protected Member Functions

Protected Attributes

Member Function Documentation

◆ GetActuatorForce()

◆ GetPoint1Abs()

◆ GetPoint2Abs()

◆ Initialize() [1/2]

◆ Initialize() [2/2]

◆ OnInitialize()

◆ SetActuatorInitialLength()

◆ SetActuatorLength()

◆ SetInitialLoad()

◆ SetInputFunction()