Detailed Description

template<typename T>
class drake::multibody::RigidBodyFrame< T >

A RigidBodyFrame is a material Frame that serves as the unique reference frame for a RigidBody.

Each RigidBody B has a unique body frame for which we use the same symbol B (with meaning clear from context). We represent a body frame by a RigidBodyFrame object that is created whenever a RigidBody is constructed and is owned by the RigidBody. All properties of a RigidBody are defined with respect to its RigidBodyFrame, including its mass properties and attachment locations for joints, constraints, actuators, geometry and so on. Run time motion of the body is defined with respect to the motion of its body frame.

Note that the body frame associated with a rigid body does not necessarily need to be located at its center of mass nor does it need to be aligned with the body's principal axes, although, in practice, it frequently is.

A RigidBodyFrame and RigidBody are tightly coupled concepts; neither makes sense without the other. Therefore, a RigidBodyFrame instance is constructed in conjunction with its RigidBody and cannot be constructed anywhere else. However, you can still access the frame associated with a body, see RigidBody::body_frame(). This access is more than a convenience; you can use the RigidBodyFrame to define other frames on the body and to attach other multibody elements to it.

Template Parameters

T	The scalar type, which must be one of the default scalars.

#include <drake/multibody/tree/rigid_body.h>

Public Member Functions
	~RigidBodyFrame () override

math::RigidTransform< T >	GetFixedPoseInBodyFrame () const override
	Variant of CalcPoseInBodyFrame() that returns the fixed pose `X_BF` of `this` frame F in the body frame B associated with this frame. More...

math::RotationMatrix< T >	GetFixedRotationMatrixInBodyFrame () const override
	Returns the rotation matrix `R_BF` that relates body frame B to `this` frame F (B is the body frame to which `this` frame F is attached). More...

math::RigidTransform< T >	GetFixedOffsetPoseInBody (const math::RigidTransform< T > &X_FQ) const override
	Variant of CalcOffsetPoseInBody() that given the offset pose `X_FQ` of a frame Q in `this` frame F, returns the pose `X_BQ` of frame Q in the body frame B to which this frame is attached. More...

math::RotationMatrix< T >	GetFixedRotationMatrixInBody (const math::RotationMatrix< T > &R_FQ) const override
	Calculates and returns the rotation matrix `R_BQ` that relates body frame B to frame Q via `this` intermediate frame F, i.e., `R_BQ = R_BF * R_FQ` (B is the body frame to which `this` frame F is attached). More...

Does not allow copy, move, or assignment
	RigidBodyFrame (const RigidBodyFrame &)=delete

RigidBodyFrame &	operator= (const RigidBodyFrame &)=delete

	RigidBodyFrame (RigidBodyFrame &&)=delete

RigidBodyFrame &	operator= (RigidBodyFrame &&)=delete

Public Member Functions inherited from Frame< T >
	~Frame () override

const RigidBody< T > &	body () const
	Returns a const reference to the body associated to this Frame. More...

bool	is_world_frame () const
	Returns true if `this` is the world frame. More...

bool	is_body_frame () const
	Returns true if `this` is the body frame. More...

const std::string &	name () const
	Returns the name of this frame. The name will never be empty. More...

ScopedName	scoped_name () const
	Returns scoped name of this frame. More...

const math::RigidTransform< T > &	EvalPoseInBodyFrame (const systems::Context< T > &context) const
	Returns a reference to the body-relative pose X_BF giving the pose of this Frame with respect to its body's RigidBodyFrame. More...

math::RigidTransform< T >	CalcPoseInBodyFrame (const systems::Context< T > &context) const
	Returns the pose `X_BF` of `this` frame F in the body frame B associated with this frame. More...

math::RotationMatrix< T >	CalcRotationMatrixInBodyFrame (const systems::Context< T > &context) const
	Returns the rotation matrix `R_BF` that relates body frame B to `this` frame F (B is the body frame to which `this` frame F is attached). More...

math::RigidTransform< T >	CalcOffsetPoseInBody (const systems::Context< T > &context, const math::RigidTransform< T > &X_FQ) const
	Given the offset pose `X_FQ` of a frame Q in `this` frame F, this method computes the pose `X_BQ` of frame Q in the body frame B to which this frame is attached. More...

math::RotationMatrix< T >	CalcOffsetRotationMatrixInBody (const systems::Context< T > &context, const math::RotationMatrix< T > &R_FQ) const
	Calculates and returns the rotation matrix `R_BQ` that relates body frame B to frame Q via `this` intermediate frame F, i.e., `R_BQ = R_BF * R_FQ` (B is the body frame to which `this` frame F is attached). More...

math::RigidTransform< T >	CalcPoseInWorld (const systems::Context< T > &context) const
	Computes and returns the pose `X_WF` of `this` frame F in the world frame W as a function of the state of the model stored in `context`. More...

math::RigidTransform< T >	CalcPose (const systems::Context< T > &context, const Frame< T > &frame_M) const
	Computes and returns the pose `X_MF` of `this` frame F in measured in `frame_M` as a function of the state of the model stored in `context`. More...

math::RotationMatrix< T >	CalcRotationMatrix (const systems::Context< T > &context, const Frame< T > &frame_M) const
	Calculates and returns the rotation matrix `R_MF` that relates `frame_M` and `this` frame F as a function of the state stored in `context`. More...

math::RotationMatrix< T >	CalcRotationMatrixInWorld (const systems::Context< T > &context) const
	Calculates and returns the rotation matrix `R_WF` that relates the world frame W and `this` frame F as a function of the state stored in `context`. More...

const Vector3< T > &	EvalAngularVelocityInWorld (const systems::Context< T > &context) const
	Evaluates `this` frame F's angular velocity measured and expressed in the world frame W. More...

Vector3< T >	CalcAngularVelocity (const systems::Context< T > &context, const Frame< T > &measured_in_frame, const Frame< T > &expressed_in_frame) const
	Calculates `this` frame F's angular velocity measured in a frame M, expressed in a frame E. More...

SpatialVelocity< T >	CalcSpatialVelocityInWorld (const systems::Context< T > &context) const
	Calculates `this` frame F's spatial velocity measured and expressed in the world frame W. More...

SpatialVelocity< T >	CalcSpatialVelocity (const systems::Context< T > &context, const Frame< T > &frame_M, const Frame< T > &frame_E) const
	Calculates `this` frame F's spatial velocity measured in a frame M, expressed in a frame E. More...

SpatialVelocity< T >	CalcRelativeSpatialVelocityInWorld (const systems::Context< T > &context, const Frame< T > &other_frame) const
	Calculates `this` frame C's spatial velocity relative to another frame B, measured and expressed in the world frame W. More...

SpatialVelocity< T >	CalcRelativeSpatialVelocity (const systems::Context< T > &context, const Frame< T > &other_frame, const Frame< T > &measured_in_frame, const Frame< T > &expressed_in_frame) const
	Calculates `this` frame C's spatial velocity relative to another frame B, measured in a frame M, expressed in a frame E. More...

SpatialAcceleration< T >	CalcSpatialAccelerationInWorld (const systems::Context< T > &context) const
	Calculates `this` frame F's spatial acceleration measured and expressed in the world frame W. More...

SpatialAcceleration< T >	CalcSpatialAcceleration (const systems::Context< T > &context, const Frame< T > &measured_in_frame, const Frame< T > &expressed_in_frame) const
	Calculates `this` frame F's spatial acceleration measured in a frame M, expressed in a frame E. More...

SpatialAcceleration< T >	CalcRelativeSpatialAccelerationInWorld (const systems::Context< T > &context, const Frame< T > &other_frame) const
	Calculates `this` frame C's spatial acceleration relative to another frame B, measured and expressed in the world frame W. More...

SpatialAcceleration< T >	CalcRelativeSpatialAcceleration (const systems::Context< T > &context, const Frame< T > &other_frame, const Frame< T > &measured_in_frame, const Frame< T > &expressed_in_frame) const
	Calculates `this` frame C's spatial acceleration relative to another frame B, measured in a frame M, expressed in a frame E. More...

template<typename ToScalar >
std::unique_ptr< Frame< ToScalar > >	CloneToScalar (const internal::MultibodyTree< ToScalar > &tree_clone) const
	(Advanced) NVI to DoCloneToScalar() templated on the scalar type of the new clone to be created. More...

	Frame (const Frame &)=delete

Frame &	operator= (const Frame &)=delete

	Frame (Frame &&)=delete

Frame &	operator= (Frame &&)=delete

void	set_body_pose_index_in_cache (int body_pose_index)
	(Internal use only) A Frame's pose-in-parent X_PF can be parameterized, the parent's pose may also be parameterized, and so on. More...

int	get_body_pose_index_in_cache () const
	(Internal use only) Retrieve this Frame's body pose index in the cache. More...

const math::RigidTransform< T > &	get_X_BF (const internal::FrameBodyPoseCache< T > &frame_body_poses) const
	(Internal use only) Given an already up-to-date frame body pose cache, extract X_BF for this Frame from it. More...

const math::RigidTransform< T > &	get_X_FB (const internal::FrameBodyPoseCache< T > &frame_body_poses) const
	(Internal use only) Given an already up-to-date frame body pose cache, extract X_FB (=X_BF⁻¹) for this Frame from it. More...

Public Member Functions inherited from FrameBase< T >
FrameIndex	index () const
	Returns this element's unique index. More...

	~FrameBase () override

Public Member Functions inherited from MultibodyElement< T >
virtual	~MultibodyElement ()

ModelInstanceIndex	model_instance () const
	Returns the ModelInstanceIndex of the model instance to which this element belongs. More...

template<typename MultibodyPlantDeferred = MultibodyPlant<T>>
const MultibodyPlantDeferred &	GetParentPlant () const
	Returns the MultibodyPlant that owns this MultibodyElement. More...

void	DeclareParameters (internal::MultibodyTreeSystem< T > *tree_system)
	Declares MultibodyTreeSystem Parameters at MultibodyTreeSystem::Finalize() time. More...

void	SetDefaultParameters (systems::Parameters< T > *parameters) const
	Sets default values of parameters belonging to each MultibodyElement in `parameters` at a call to MultibodyTreeSystem::SetDefaultParameters(). More...

	MultibodyElement (const MultibodyElement &)=delete

MultibodyElement &	operator= (const MultibodyElement &)=delete

	MultibodyElement (MultibodyElement &&)=delete

MultibodyElement &	operator= (MultibodyElement &&)=delete

Protected Member Functions
std::unique_ptr< Frame< double > >	DoCloneToScalar (const internal::MultibodyTree< double > &tree_clone) const override
	Clones this Frame (templated on T) to a frame templated on `double`. More...

std::unique_ptr< Frame< AutoDiffXd > >	DoCloneToScalar (const internal::MultibodyTree< AutoDiffXd > &tree_clone) const override
	Clones this Frame (templated on T) to a frame templated on AutoDiffXd. More...

std::unique_ptr< Frame< symbolic::Expression > >	DoCloneToScalar (const internal::MultibodyTree< symbolic::Expression > &) const override

math::RigidTransform< T >	DoCalcPoseInBodyFrame (const systems::Parameters< T > &) const override

math::RotationMatrix< T >	DoCalcRotationMatrixInBodyFrame (const systems::Parameters< T > &) const override

math::RigidTransform< T >	DoCalcOffsetPoseInBody (const systems::Parameters< T > &, const math::RigidTransform< T > &X_FQ) const override

math::RotationMatrix< T >	DoCalcOffsetRotationMatrixInBody (const systems::Parameters< T > &, const math::RotationMatrix< T > &R_FQ) const override

Protected Member Functions inherited from Frame< T >
	Frame (const std::string &name, const RigidBody< T > &body, std::optional< ModelInstanceIndex > model_instance={})
	Only derived classes can use this constructor. More...

virtual void	DoDeclareFrameParameters (internal::MultibodyTreeSystem< T > *)
	Called by DoDeclareParameters(). More...

virtual void	DoSetDefaultFrameParameters (systems::Parameters< T > *) const
	Called by DoSetDefaultParameters(). More...

Protected Member Functions inherited from FrameBase< T >
	FrameBase (ModelInstanceIndex model_instance)

Protected Member Functions inherited from MultibodyElement< T >
	MultibodyElement ()
	Default constructor made protected so that sub-classes can still declare their default constructors if they need to. More...

	MultibodyElement (ModelInstanceIndex model_instance)
	Constructor which allows specifying a model instance. More...

	MultibodyElement (ModelInstanceIndex model_instance, int64_t index)
	Both the model instance and element index are specified. More...

template<typename ElementIndexType >
ElementIndexType	index_impl () const
	Returns this element's unique index. More...

int	ordinal_impl () const
	Returns this element's unique ordinal. More...

const internal::MultibodyTree< T > &	get_parent_tree () const
	Returns a constant reference to the parent MultibodyTree that owns this element. More...

const internal::MultibodyTreeSystem< T > &	GetParentTreeSystem () const
	Returns a constant reference to the parent MultibodyTreeSystem that owns the parent MultibodyTree that owns this element. More...

void	SetTopology (const internal::MultibodyTreeTopology &tree)
	Gives MultibodyElement-derived objects the opportunity to retrieve their topology after MultibodyTree::Finalize() is invoked. More...

systems::NumericParameterIndex	DeclareNumericParameter (internal::MultibodyTreeSystem< T > *tree_system, const systems::BasicVector< T > &model_vector)
	To be used by MultibodyElement-derived objects when declaring parameters in their implementation of DoDeclareParameters(). More...

systems::AbstractParameterIndex	DeclareAbstractParameter (internal::MultibodyTreeSystem< T > *tree_system, const AbstractValue &model_value)
	To be used by MultibodyElement-derived objects when declaring parameters in their implementation of DoDeclareParameters(). More...

Friends
class	RigidBody< T >

template<typename >
class	RigidBodyFrame

Constructor & Destructor Documentation

◆ RigidBodyFrame() [1/2]

RigidBodyFrame ( const RigidBodyFrame< T > & )

delete

◆ RigidBodyFrame() [2/2]

RigidBodyFrame ( RigidBodyFrame< T > && )

delete

◆ ~RigidBodyFrame()

~RigidBodyFrame ( )

override

Member Function Documentation

◆ DoCalcOffsetPoseInBody()

math::RigidTransform<T> DoCalcOffsetPoseInBody	(	const systems::Parameters< T > &	,
		const math::RigidTransform< T > &	X_FQ
	)		const

overrideprotectedvirtual

Reimplemented from Frame< T >.

◆ DoCalcOffsetRotationMatrixInBody()

math::RotationMatrix<T> DoCalcOffsetRotationMatrixInBody	(	const systems::Parameters< T > &	,
		const math::RotationMatrix< T > &	R_FQ
	)		const

overrideprotectedvirtual

Reimplemented from Frame< T >.

◆ DoCalcPoseInBodyFrame()

math::RigidTransform<T> DoCalcPoseInBodyFrame ( const systems::Parameters< T > & ) const

overrideprotectedvirtual

Implements Frame< T >.

◆ DoCalcRotationMatrixInBodyFrame()

math::RotationMatrix<T> DoCalcRotationMatrixInBodyFrame ( const systems::Parameters< T > & ) const

overrideprotectedvirtual

Implements Frame< T >.

◆ DoCloneToScalar() [1/3]

std::unique_ptr<Frame<double> > DoCloneToScalar ( const internal::MultibodyTree< double > & tree_clone ) const

overrideprotectedvirtual

Clones this Frame (templated on T) to a frame templated on double.

Implements Frame< T >.

◆ DoCloneToScalar() [2/3]

std::unique_ptr<Frame<AutoDiffXd> > DoCloneToScalar ( const internal::MultibodyTree< AutoDiffXd > & tree_clone ) const

overrideprotectedvirtual

Clones this Frame (templated on T) to a frame templated on AutoDiffXd.

Implements Frame< T >.

◆ DoCloneToScalar() [3/3]

std::unique_ptr<Frame<symbolic::Expression> > DoCloneToScalar ( const internal::MultibodyTree< symbolic::Expression > & ) const

overrideprotectedvirtual

Implements Frame< T >.

◆ GetFixedOffsetPoseInBody()

math::RigidTransform<T> GetFixedOffsetPoseInBody ( const math::RigidTransform< T > & X_FQ ) const

overridevirtual

Variant of CalcOffsetPoseInBody() that given the offset pose X_FQ of a frame Q in this frame F, returns the pose X_BQ of frame Q in the body frame B to which this frame is attached.

Exceptions

std::exception if called on a Frame that does not have a fixed offset in the body frame.

Reimplemented from Frame< T >.

◆ GetFixedPoseInBodyFrame()

math::RigidTransform<T> GetFixedPoseInBodyFrame ( ) const

overridevirtual

Variant of CalcPoseInBodyFrame() that returns the fixed pose X_BF of this frame F in the body frame B associated with this frame.

Exceptions

std::exception if called on a Frame that does not have a fixed offset in the body frame.

Reimplemented from Frame< T >.

◆ GetFixedRotationMatrixInBody()

math::RotationMatrix<T> GetFixedRotationMatrixInBody ( const math::RotationMatrix< T > & R_FQ ) const

overridevirtual

Calculates and returns the rotation matrix R_BQ that relates body frame B to frame Q via this intermediate frame F, i.e., R_BQ = R_BF * R_FQ (B is the body frame to which this frame F is attached).

Parameters

[in] R_FQ rotation matrix that relates frame F to frame Q.

Exceptions

std::exception if this frame F is a Frame that does not have a fixed offset in the body frame B (i.e., R_BF is not constant).

Reimplemented from Frame< T >.

◆ GetFixedRotationMatrixInBodyFrame()

math::RotationMatrix<T> GetFixedRotationMatrixInBodyFrame ( ) const

overridevirtual

Returns the rotation matrix R_BF that relates body frame B to this frame F (B is the body frame to which this frame F is attached).

Exceptions

std::exception if this frame F is a Frame that does not have a fixed offset in the body frame B (i.e., R_BF is not constant). Frame sub-classes that have a constant R_BF must override this method. An example of a frame sub-class not implementing this method would be that of a frame on a soft body, for which its pose in the body frame depends on the state of deformation of the body.

Reimplemented from Frame< T >.

◆ operator=() [1/2]

RigidBodyFrame& operator= ( const RigidBodyFrame< T > & )

delete

◆ operator=() [2/2]

RigidBodyFrame& operator= ( RigidBodyFrame< T > && )

delete

Friends And Related Function Documentation

◆ RigidBody< T >

friend class RigidBody< T >

friend

◆ RigidBodyFrame

friend class RigidBodyFrame

friend

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

drake/multibody/tree/fixed_offset_frame.h
drake/multibody/tree/rigid_body.h

Detailed Description

template<typename T> class drake::multibody::RigidBodyFrame< T >

Public Member Functions

Protected Member Functions

Friends

Constructor & Destructor Documentation

◆ RigidBodyFrame() [1/2]

◆ RigidBodyFrame() [2/2]

◆ ~RigidBodyFrame()

Member Function Documentation

◆ DoCalcOffsetPoseInBody()

◆ DoCalcOffsetRotationMatrixInBody()

◆ DoCalcPoseInBodyFrame()

◆ DoCalcRotationMatrixInBodyFrame()

◆ DoCloneToScalar() [1/3]

◆ DoCloneToScalar() [2/3]

◆ DoCloneToScalar() [3/3]

◆ GetFixedOffsetPoseInBody()

◆ GetFixedPoseInBodyFrame()

◆ GetFixedRotationMatrixInBody()

◆ GetFixedRotationMatrixInBodyFrame()

◆ operator=() [1/2]

◆ operator=() [2/2]

Friends And Related Function Documentation

◆ RigidBody< T >

◆ RigidBodyFrame

template<typename T>
class drake::multibody::RigidBodyFrame< T >