Basic rigid-body model representing a system of rigid-bodies connected by 1-6 DoF joints. More...

Inheritance diagram for rigidBodyModel:

Collaboration diagram for rigidBodyModel:

Public Member Functions
	TypeName ("rigidBodyModel")
	Runtime type information. More...

	rigidBodyModel (const Time &time)
	Null-constructor which adds the single root-body at the origin. More...

	rigidBodyModel (const Time &time, const dictionary &dict)
	Construct from dictionary. More...

virtual	~rigidBodyModel ()
	Destructor. More...

const Time &	time () const
	Return the time. More...

label	nBodies () const
	Return the number of bodies in the model (bodies().size()) More...

PtrList< rigidBody >	bodies () const
	Return the list of the bodies in the model. More...

const DynamicList< label > &	lambda () const
	List of indices of the parent of each body. More...

const PtrList< joint > &	joints () const
	Return the list of joints in the model. More...

label	nDoF () const
	Return the number of degrees of freedom of the model. More...

bool	unitQuaternions () const
	Return true if any of the joints using quaternions. More...

const vector &	g () const
	Return the acceleration due to gravity. More...

vector &	g ()
	Allow the acceleration due to gravity to be set. More...

const word &	name (const label bodyID) const
	Return the name of body with the given ID. More...

const rigidBodyInertia &	I (const label i) const
	Return the inertia of body i. More...

const spatialVector &	v (const label i) const
	Return the spatial velocity of the bodies. More...

const spatialVector &	a (const label i) const
	Return the spatial acceleration of the bodies. More...

virtual label	join (const label parentID, const spatialTransform &XT, autoPtr< joint > jointPtr, autoPtr< rigidBody > bodyPtr)
	Join the given body to the parent with ID parentID via the given. More...

label	join (const label parentID, const spatialTransform &XT, autoPtr< joints::composite > cJoint, autoPtr< rigidBody > bodyPtr)
	Join the given body to the parent with ID parentID via the given. More...

label	merge (const label parentID, const spatialTransform &X, autoPtr< rigidBody > bodyPtr)
	Merge the given body with transform X into the parent with ID. More...

bool	merged (label bodyID) const
	Return true if the body with given ID has been merged with a parent. More...

label	master (label bodyID) const
	Return the ID of the master body for a sub-body otherwise. More...

label	mergedBodyIndex (const label mergedBodyID) const
	Return the index of the merged body in the mergedBody list. More...

label	mergedBodyID (const label mergedBodyIndex) const
	Return the merged body ID for the given merged body index. More...

const subBody &	mergedBody (label mergedBodyID) const
	Return the merged body for the given body ID. More...

label	bodyID (const word &name) const
	Return the ID of the body with the given name. More...

spatialTransform	X0 (const label bodyId) const
	Return the current transform to the global frame for the given body. More...

vector	masterPoint (const label bodyID, const vector &p) const

spatialVector	v (const label bodyID, const vector &p) const
	Return the velocity of the given point on the given body. More...

void	applyRestraints (scalarField &tau, Field< spatialVector > &fx, const rigidBodyModelState &state) const
	Apply the restraints and accumulate the internal joint forces. More...

void	forwardDynamics (rigidBodyModelState &state, const scalarField &tau, const Field< spatialVector > &fx) const
	Calculate the joint acceleration qDdot from the joint state q,. More...

void	forwardDynamicsCorrection (const rigidBodyModelState &state) const
	Correct the velocity and acceleration of the bodies in the model. More...

virtual void	write (Ostream &) const
	Write. More...

bool	read (const dictionary &dict)
	Read coefficients dictionary and update system parameters,. More...

Protected Member Functions
virtual label	join_ (const label parentID, const spatialTransform &XT, autoPtr< joint > jointPtr, autoPtr< rigidBody > bodyPtr)
	Join the given body to the parent with ID parentID via the given. More...

Protected Attributes
const Time &	time_
	Reference to time database. More...

PtrList< rigidBody >	bodies_
	List of the bodies. More...

PtrList< subBody >	mergedBodies_
	Bodies may be merged into existing bodies, the inertia of which is. More...

HashTable< label >	bodyIDs_
	Lookup-table of the IDs of the bodies. More...

DynamicList< label >	lambda_
	List of indices of the parent of each body. More...

PtrList< joint >	joints_
	Each body it attached with a joint which are held on this list. More...

DynamicList< spatialTransform >	XT_
	Transform from the parent body frame to the joint frame. More...

label	nDoF_
	The number of degrees of freedom of the model. More...

bool	unitQuaternions_
	True if any of the joints using quaternions. More...

PtrList< restraint >	restraints_
	Motion restraints. More...

vector	g_
	Acceleration due to gravity. More...

DynamicList< spatialTransform >	Xlambda_
	Transform from the parent body to the current body. More...

DynamicList< spatialTransform >	X0_
	Transform for external forces to the bodies reference frame. More...

DynamicList< spatialVector >	v_
	The spatial velocity of the bodies. More...

DynamicList< spatialVector >	a_
	The spatial acceleration of the bodies. More...

DynamicList< spatialVector >	c_
	The velocity dependent spatial acceleration of the joints. More...

DynamicList< spatialTensor >	IA_
	Velocity-product acceleration. More...

DynamicList< spatialVector >	pA_
	Articulated body bias force. More...

DynamicList< compactSpatialTensor >	S_
	Motion subspace for joints with 3 degrees of freedom. More...

DynamicList< spatialVector >	S1_
	Motion subspace for joints with 1 degrees of freedom. More...

DynamicList< compactSpatialTensor >	U_
	Sub-expression IA.S in the forward-dynamics algorithm. More...

DynamicList< spatialVector >	U1_
	Sub-expression IA.S1 in the forward-dynamics algorithm. More...

DynamicList< tensor >	Dinv_
	Sub-expression (S^T.U)^-1 in the forward-dynamics algorithm. More...

DynamicList< vector >	u_
	Sub-expression tau - S^T.pA in the forward-dynamics algorithm. More...

Friends
Ostream &	operator<< (Ostream &, const rigidBodyModel &)

Detailed Description

Basic rigid-body model representing a system of rigid-bodies connected by 1-6 DoF joints.

This class holds various body and joint state fields needed by the kinematics and forward-dynamics algorithms presented in

reference:

    Featherstone, R. (2008).
    Rigid body dynamics algorithms.
    Springer.
    Chapter 4.

Source files

Definition at line 83 of file rigidBodyModel.H.

Constructor & Destructor Documentation

◆ rigidBodyModel() [1/2]

rigidBodyModel ( const Time & time )

Null-constructor which adds the single root-body at the origin.

Definition at line 169 of file rigidBodyModel.C.

◆ rigidBodyModel() [2/2]

rigidBodyModel	(	const Time &	time,
		const dictionary &	dict
	)

Construct from dictionary.

Definition at line 179 of file rigidBodyModel.C.

References dict, dictionary::found(), dictionary::get(), rigidBody::New(), joint::New(), Foam::read(), and dictionary::subDict().

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◆ ~rigidBodyModel()

~rigidBodyModel ( )

virtual

Destructor.

Definition at line 224 of file rigidBodyModel.C.

Member Function Documentation

◆ join_()

Foam::label join_	(	const label	parentID,
		const spatialTransform &	XT,
		autoPtr< joint >	jointPtr,
		autoPtr< rigidBody >	bodyPtr
	)

protectedvirtual

Join the given body to the parent with ID parentID via the given.

joint with transform from the parent frame to the joint frame XT.

Definition at line 123 of file rigidBodyModel.C.

References subBody::masterID(), subBody::masterXT(), rigidBody::name(), joint::nDoF(), and joint::unitQuaternion().

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◆ TypeName()

TypeName ( "rigidBodyModel" )

Runtime type information.

◆ time()

const Foam::Time & time ( ) const

inline

Return the time.

Definition at line 31 of file rigidBodyModelI.H.

References rigidBodyModel::time_.

◆ nBodies()

Foam::label nBodies ( ) const

inline

Return the number of bodies in the model (bodies().size())

Definition at line 37 of file rigidBodyModelI.H.

◆ bodies()

Foam::PtrList< Foam::RBD::rigidBody > bodies ( ) const

inline

Return the list of the bodies in the model.

Definition at line 44 of file rigidBodyModelI.H.

◆ lambda()

const Foam::DynamicList< Foam::label > & lambda ( ) const

inline

List of indices of the parent of each body.

Definition at line 51 of file rigidBodyModelI.H.

◆ joints()

const Foam::PtrList< Foam::RBD::joint > & joints ( ) const

inline

Return the list of joints in the model.

Definition at line 58 of file rigidBodyModelI.H.

◆ nDoF()

Foam::label nDoF ( ) const

inline

Return the number of degrees of freedom of the model.

used to set the size of the of joint state fields q, qDot and qDdot.

Definition at line 64 of file rigidBodyModelI.H.

Referenced by rigidBodyModelState::rigidBodyModelState().

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◆ unitQuaternions()

bool unitQuaternions ( ) const

inline

Return true if any of the joints using quaternions.

Definition at line 70 of file rigidBodyModelI.H.

◆ g() [1/2]

const Foam::vector & g ( ) const

inline

Return the acceleration due to gravity.

Definition at line 76 of file rigidBodyModelI.H.

◆ g() [2/2]

Foam::vector & g ( )

inline

Allow the acceleration due to gravity to be set.

after model construction

Definition at line 82 of file rigidBodyModelI.H.

◆ name()

const Foam::word & name ( const label bodyID ) const

inline

Return the name of body with the given ID.

Definition at line 89 of file rigidBodyModelI.H.

◆ I()

const Foam::RBD::rigidBodyInertia & I ( const label i ) const

inline

Return the inertia of body i.

Definition at line 105 of file rigidBodyModelI.H.

◆ v() [1/2]

const Foam::spatialVector & v ( const label i ) const

inline

Return the spatial velocity of the bodies.

Definition at line 112 of file rigidBodyModelI.H.

◆ a()

const Foam::spatialVector & a ( const label i ) const

inline

Return the spatial acceleration of the bodies.

Definition at line 118 of file rigidBodyModelI.H.

◆ join() [1/2]

Foam::label join	(	const label	parentID,
		const spatialTransform &	XT,
		autoPtr< joint >	jointPtr,
		autoPtr< rigidBody >	bodyPtr
	)

virtual

Join the given body to the parent with ID parentID via the given.

joint with transform from the parent frame to the joint frame XT.

Definition at line 231 of file rigidBodyModel.C.

References autoPtr< T >::ptr().

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◆ join() [2/2]

Foam::label join	(	const label	parentID,
		const spatialTransform &	XT,
		autoPtr< joints::composite >	cJoint,
		autoPtr< rigidBody >	bodyPtr
	)

Join the given body to the parent with ID parentID via the given.

composite joint (specified as a list of co-located joints) with transform from the parent frame to the joint frame XT. Composite joins are useful to represent complex joints with degrees of freedom other than 1 or 3 which are directly supported.

Definition at line 265 of file rigidBodyModel.C.

References autoPtr< T >::ptr().

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◆ merge()

Foam::label merge	(	const label	parentID,
		const spatialTransform &	X,
		autoPtr< rigidBody >	bodyPtr
	)

Merge the given body with transform X into the parent with ID.

parentID. The parent body assumes the properties of the combined body (inertia etc.) and the merged body is held on a separate list for reference.

Definition at line 323 of file rigidBodyModel.C.

References subBody::masterID(), subBody::masterXT(), subBody::name(), Foam::name(), and autoPtr< T >::reset().

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◆ merged()

bool merged ( label bodyID ) const

inline

Return true if the body with given ID has been merged with a parent.

Definition at line 123 of file rigidBodyModelI.H.

◆ master()

Foam::label master ( label bodyID ) const

inline

Return the ID of the master body for a sub-body otherwise.

return the given body ID

Definition at line 129 of file rigidBodyModelI.H.

◆ mergedBodyIndex()

Foam::label mergedBodyIndex ( const label mergedBodyID ) const

inline

Return the index of the merged body in the mergedBody list.

from the given body ID

Definition at line 150 of file rigidBodyModelI.H.

◆ mergedBodyID()

Foam::label mergedBodyID ( const label mergedBodyIndex ) const

inline

Return the merged body ID for the given merged body index.

in the mergedBody list

Definition at line 143 of file rigidBodyModelI.H.

◆ mergedBody()

const Foam::RBD::subBody & mergedBody ( label mergedBodyID ) const

inline

Return the merged body for the given body ID.

Definition at line 157 of file rigidBodyModelI.H.

References Foam::abort(), Foam::FatalError, and FatalErrorInFunction.

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◆ bodyID()

Foam::label bodyID ( const word & name ) const

inline

Return the ID of the body with the given name.

Definition at line 170 of file rigidBodyModelI.H.

References Foam::name().

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◆ X0()

Foam::spatialTransform X0 ( const label bodyId ) const

Return the current transform to the global frame for the given body.

Definition at line 381 of file rigidBodyModel.C.

References subBody::masterID(), and subBody::masterXT().

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◆ masterPoint()

Foam::vector masterPoint	(	const label	bodyID,
		const vector &	p
	)		const

inline

Definition at line 177 of file rigidBodyModelI.H.

References Foam::inv(), p, and Foam::Zero.

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◆ v() [2/2]

Foam::spatialVector v	(	const label	bodyID,
		const vector &	p
	)		const

inline

Return the velocity of the given point on the given body.

Definition at line 198 of file rigidBodyModelI.H.

References p, and Foam::T().

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◆ applyRestraints()

void applyRestraints	(	scalarField &	tau,
		Field< spatialVector > &	fx,
		const rigidBodyModelState &	state
	)		const

Apply the restraints and accumulate the internal joint forces.

into the tau field and external forces into the fx field

Definition at line 35 of file forwardDynamics.C.

References DebugInfo, and forAll.

◆ forwardDynamics()

void forwardDynamics	(	rigidBodyModelState &	state,
		const scalarField &	tau,
		const Field< spatialVector > &	fx
	)		const

Calculate the joint acceleration qDdot from the joint state q,.

velocity qDot, internal force tau (in the joint frame) and external force fx (in the global frame) using the articulated body algorithm (Section 7.3 and Table 7.1)

Definition at line 57 of file forwardDynamics.C.

References Field< Type >::block(), joint::XSvc::c, DebugInfo, DebugInFunction, Foam::endl(), Foam::I, Foam::inv(), joint::jcalc(), joint::nDoF(), Foam::nl, rigidBodyModelState::q(), rigidBodyModelState::qDdot(), rigidBodyModelState::qDot(), joint::XSvc::S, joint::XSvc::S1, T, joint::XSvc::v, x, Vector< Cmpt >::x(), joint::XSvc::X, Vector< Cmpt >::y(), Vector< Cmpt >::z(), and Foam::Zero.

Referenced by rigidBodyMotion::forwardDynamics().

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◆ forwardDynamicsCorrection()

void forwardDynamicsCorrection ( const rigidBodyModelState & state ) const

Correct the velocity and acceleration of the bodies in the model.

from the given joint state fields following an integration step of the forwardDynamics

Definition at line 210 of file forwardDynamics.C.

References Field< Type >::block(), joint::XSvc::c, DebugInfo, DebugInFunction, Foam::endl(), joint::jcalc(), joint::nDoF(), rigidBodyModelState::q(), rigidBodyModelState::qDdot(), rigidBodyModelState::qDot(), joint::XSvc::S, joint::XSvc::S1, joint::XSvc::v, joint::XSvc::X, and Foam::Zero.

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◆ write()

void write ( Ostream & os ) const

virtual

Write.

Reimplemented in rigidBodyMotion.

Definition at line 395 of file rigidBodyModel.C.

References Ostream::beginBlock(), Ostream::endBlock(), Foam::endl(), forAll, Foam::indent(), Foam::name(), Foam::nl, Ostream::write(), and Ostream::writeEntry().

Referenced by Foam::RBD::operator<<(), and rigidBodyMotion::write().

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◆ read()

bool read ( const dictionary & dict )

Read coefficients dictionary and update system parameters,.

restraints but not the current state

Definition at line 456 of file rigidBodyModel.C.

References dict.

Referenced by rigidBodyMotion::read().

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Friends And Related Function Documentation

◆ operator<<

Ostream& operator<<	(	Ostream &	,
		const rigidBodyModel &
	)

friend

Member Data Documentation

◆ time_

const Time& time_

protected

Reference to time database.

Definition at line 103 of file rigidBodyModel.H.

Referenced by rigidBodyModel::time().

◆ bodies_

PtrList<rigidBody> bodies_

protected

List of the bodies.

The 0'th body represents the fixed origin and is constructed automatically. The subsequent (moving) bodies are appended by the join member function.

Definition at line 111 of file rigidBodyModel.H.

◆ mergedBodies_

PtrList<subBody> mergedBodies_

protected

Bodies may be merged into existing bodies, the inertia of which is.

updated to represent the combined body which is more efficient than attaching them with fixed joints. These 'merged' bodies are held on this list.

Definition at line 117 of file rigidBodyModel.H.

◆ bodyIDs_

HashTable<label> bodyIDs_

protected

Lookup-table of the IDs of the bodies.

Definition at line 120 of file rigidBodyModel.H.

◆ lambda_

DynamicList<label> lambda_

protected

List of indices of the parent of each body.

Definition at line 123 of file rigidBodyModel.H.

◆ joints_

PtrList<joint> joints_

protected

Each body it attached with a joint which are held on this list.

Definition at line 126 of file rigidBodyModel.H.

◆ XT_

DynamicList<spatialTransform> XT_

protected

Transform from the parent body frame to the joint frame.

Definition at line 129 of file rigidBodyModel.H.

◆ nDoF_

label nDoF_

protected

The number of degrees of freedom of the model.

used to set the size of the of joint state fields q, qDot and qDdot.

Definition at line 133 of file rigidBodyModel.H.

◆ unitQuaternions_

bool unitQuaternions_

protected

True if any of the joints using quaternions.

Definition at line 136 of file rigidBodyModel.H.

◆ restraints_

PtrList<restraint> restraints_

protected

Motion restraints.

Definition at line 139 of file rigidBodyModel.H.

◆ g_

vector g_

protected

Acceleration due to gravity.

Definition at line 145 of file rigidBodyModel.H.

◆ Xlambda_

DynamicList<spatialTransform> Xlambda_

mutableprotected

Transform from the parent body to the current body.

Definition at line 151 of file rigidBodyModel.H.

◆ X0_

DynamicList<spatialTransform> X0_

mutableprotected

Transform for external forces to the bodies reference frame.

Definition at line 154 of file rigidBodyModel.H.

◆ v_

DynamicList<spatialVector> v_

mutableprotected

The spatial velocity of the bodies.

Definition at line 160 of file rigidBodyModel.H.

◆ a_

DynamicList<spatialVector> a_

mutableprotected

The spatial acceleration of the bodies.

Definition at line 163 of file rigidBodyModel.H.

◆ c_

DynamicList<spatialVector> c_

mutableprotected

The velocity dependent spatial acceleration of the joints.

Definition at line 166 of file rigidBodyModel.H.

◆ IA_

DynamicList<spatialTensor> IA_

mutableprotected

Velocity-product acceleration.

Articulated body inertia

Definition at line 174 of file rigidBodyModel.H.

◆ pA_

DynamicList<spatialVector> pA_

mutableprotected

Articulated body bias force.

Definition at line 177 of file rigidBodyModel.H.

◆ S_

DynamicList<compactSpatialTensor> S_

mutableprotected

Motion subspace for joints with 3 degrees of freedom.

Definition at line 183 of file rigidBodyModel.H.

◆ S1_

DynamicList<spatialVector> S1_

mutableprotected

Motion subspace for joints with 1 degrees of freedom.

Definition at line 186 of file rigidBodyModel.H.

◆ U_

DynamicList<compactSpatialTensor> U_

mutableprotected

Sub-expression IA.S in the forward-dynamics algorithm.

Definition at line 189 of file rigidBodyModel.H.

◆ U1_

DynamicList<spatialVector> U1_

mutableprotected

Sub-expression IA.S1 in the forward-dynamics algorithm.

Definition at line 192 of file rigidBodyModel.H.

◆ Dinv_

DynamicList<tensor> Dinv_

mutableprotected

Sub-expression (S^T.U)^-1 in the forward-dynamics algorithm.

Definition at line 195 of file rigidBodyModel.H.

◆ u_

DynamicList<vector> u_

mutableprotected

Sub-expression tau - S^T.pA in the forward-dynamics algorithm.

Definition at line 198 of file rigidBodyModel.H.

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

src/rigidBodyDynamics/rigidBodyModel/rigidBodyModel.H
src/rigidBodyDynamics/rigidBodyModel/forwardDynamics.C
src/rigidBodyDynamics/rigidBodyModel/rigidBodyModel.C
src/rigidBodyDynamics/rigidBodyModel/rigidBodyModelI.H

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ rigidBodyModel() [1/2]

◆ rigidBodyModel() [2/2]

◆ ~rigidBodyModel()

Member Function Documentation

◆ join_()

◆ TypeName()

◆ time()

◆ nBodies()

◆ bodies()

◆ lambda()

◆ joints()

◆ nDoF()

◆ unitQuaternions()

◆ g() [1/2]

◆ g() [2/2]

◆ name()

◆ I()

◆ v() [1/2]

◆ a()

◆ join() [1/2]

◆ join() [2/2]

◆ merge()

◆ merged()

◆ master()

◆ mergedBodyIndex()

◆ mergedBodyID()

◆ mergedBody()

◆ bodyID()

◆ X0()

◆ masterPoint()

◆ v() [2/2]

◆ applyRestraints()

◆ forwardDynamics()

◆ forwardDynamicsCorrection()

◆ write()

◆ read()

Friends And Related Function Documentation

◆ operator<<

Member Data Documentation

◆ time_

◆ bodies_

◆ mergedBodies_

◆ bodyIDs_

◆ lambda_

◆ joints_

◆ XT_

◆ nDoF_

◆ unitQuaternions_

◆ restraints_

◆ g_

◆ Xlambda_

◆ X0_

◆ v_

◆ a_

◆ c_

◆ IA_

◆ pA_

◆ S_

◆ S1_

◆ U_

◆ U1_

◆ Dinv_

◆ u_