Detailed Description

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

This Joint fixes the relative pose between two frames as if "welding" them together.

Template Parameters

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

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

Public Types
template<typename Scalar >
using	Context = systems::Context< Scalar >

Public Member Functions
	WeldJoint (const std::string &name, const Frame< T > &frame_on_parent_F, const Frame< T > &frame_on_child_M, const math::RigidTransform< double > &X_FM)
	Constructor for a WeldJoint between a `frame_on_parent_F` and a `frame_on_child_M` so that their relative pose `X_FM` is fixed as if they were "welded" together. More...

	~WeldJoint () override

const std::string &	type_name () const override
	Returns a string identifying the type of `this` joint, such as "revolute" or "prismatic". More...

const math::RigidTransform< double > &	X_FM () const
	Returns the pose X_FM of frame M in F. More...

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

WeldJoint &	operator= (const WeldJoint &)=delete

	WeldJoint (WeldJoint &&)=delete

WeldJoint &	operator= (WeldJoint &&)=delete

Public Member Functions inherited from Joint< T >
	Joint (const std::string &name, const Frame< T > &frame_on_parent, const Frame< T > &frame_on_child, VectorX< double > damping, const VectorX< double > &pos_lower_limits, const VectorX< double > &pos_upper_limits, const VectorX< double > &vel_lower_limits, const VectorX< double > &vel_upper_limits, const VectorX< double > &acc_lower_limits, const VectorX< double > &acc_upper_limits)
	Creates a joint between two Frame objects which imposes a given kinematic relation between frame F attached on the parent body P and frame M attached on the child body B. More...

	Joint (const std::string &name, const Frame< T > &frame_on_parent, const Frame< T > &frame_on_child, const VectorX< double > &pos_lower_limits, const VectorX< double > &pos_upper_limits, const VectorX< double > &vel_lower_limits, const VectorX< double > &vel_upper_limits, const VectorX< double > &acc_lower_limits, const VectorX< double > &acc_upper_limits)
	Additional constructor overload for joints with zero damping. More...

virtual	~Joint ()

JointIndex	index () const
	Returns this element's unique index. More...

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

const std::string &	name () const
	Returns the name of this joint. More...

const RigidBody< T > &	parent_body () const
	Returns a const reference to the parent body P. More...

const RigidBody< T > &	child_body () const
	Returns a const reference to the child body B. More...

const Frame< T > &	frame_on_parent () const
	Returns a const reference to the frame F attached on the parent body P. More...

const Frame< T > &	frame_on_child () const
	Returns a const reference to the frame M attached on the child body B. More...

int	velocity_start () const
	Returns the index to the first generalized velocity for this joint within the vector v of generalized velocities for the full multibody system. More...

int	num_velocities () const
	Returns the number of generalized velocities describing this joint. More...

int	position_start () const
	Returns the index to the first generalized position for this joint within the vector q of generalized positions for the full multibody system. More...

int	num_positions () const
	Returns the number of generalized positions describing this joint. More...

bool	can_rotate () const
	Returns true if this joint's mobility allows relative rotation of the two frames associated with this joint. More...

bool	can_translate () const
	Returns true if this joint's mobility allows relative translation of the two frames associated with this joint. More...

std::string	position_suffix (int position_index_in_joint) const
	Returns a string suffix (e.g. More...

std::string	velocity_suffix (int velocity_index_in_joint) const
	Returns a string suffix (e.g. More...

const T &	GetOnePosition (const systems::Context< T > &context) const
	Returns the position coordinate for joints with a single degree of freedom. More...

const T &	GetOneVelocity (const systems::Context< T > &context) const
	Returns the velocity coordinate for joints with a single degree of freedom. More...

void	AddInOneForce (const systems::Context< T > &context, int joint_dof, const T &joint_tau, MultibodyForces< T > *forces) const
	Adds into `forces` a force along the one of the joint's degrees of freedom indicated by index `joint_dof`. More...

void	AddInDamping (const systems::Context< T > &context, MultibodyForces< T > *forces) const
	Adds into `forces` the force due to damping within `this` joint. More...

void	Lock (systems::Context< T > *context) const
	Lock the joint. More...

void	Unlock (systems::Context< T > *context) const
	Unlock the joint. More...

bool	is_locked (const systems::Context< T > &context) const

const VectorX< double > &	default_damping_vector () const
	Returns all default damping coefficients for joints that model viscous damping, of size num_velocities(). More...

const VectorX< T > &	GetDampingVector (const systems::Context< T > &context) const
	Returns the Context dependent damping coefficients stored as parameters in `context`. More...

void	set_default_damping_vector (const VectorX< double > &damping)
	Sets the default value of the viscous damping coefficients for this joint. More...

void	SetDampingVector (systems::Context< T > *context, const VectorX< T > &damping) const
	Sets the value of the viscous damping coefficients for this joint, stored as parameters in `context`. More...

	Joint (const Joint &)=delete

Joint &	operator= (const Joint &)=delete

	Joint (Joint &&)=delete

Joint &	operator= (Joint &&)=delete

const VectorX< double > &	position_lower_limits () const
	Returns the position lower limits. More...

const VectorX< double > &	position_upper_limits () const
	Returns the position upper limits. More...

const VectorX< double > &	velocity_lower_limits () const
	Returns the velocity lower limits. More...

const VectorX< double > &	velocity_upper_limits () const
	Returns the velocity upper limits. More...

const VectorX< double > &	acceleration_lower_limits () const
	Returns the acceleration lower limits. More...

const VectorX< double > &	acceleration_upper_limits () const
	Returns the acceleration upper limits. More...

void	set_position_limits (const VectorX< double > &lower_limits, const VectorX< double > &upper_limits)
	Sets the position limits to `lower_limits` and `upper_limits`. More...

void	set_velocity_limits (const VectorX< double > &lower_limits, const VectorX< double > &upper_limits)
	Sets the velocity limits to `lower_limits` and `upper_limits`. More...

void	set_acceleration_limits (const VectorX< double > &lower_limits, const VectorX< double > &upper_limits)
	Sets the acceleration limits to `lower_limits` and `upper_limits`. More...

void	set_default_positions (const VectorX< double > &default_positions)
	Sets the default generalized position coordinates q₀ to `default_positions`. More...

const VectorX< double > &	default_positions () const
	Returns the default generalized position coordinates q₀. More...

void	SetPositions (systems::Context< T > *context, const Eigen::Ref< const VectorX< T >> &positions) const
	Sets in the given `context` the generalized position coordinates q for this joint to `positions`. More...

Eigen::Ref< const VectorX< T > >	GetPositions (const systems::Context< T > &context) const
	Returns the current value in the given `context` of the generalized coordinates q for this joint. More...

void	SetVelocities (systems::Context< T > *context, const Eigen::Ref< const VectorX< T >> &velocities) const
	Sets in the given `context` the generalized velocity coordinates v for this joint to `velocities`. More...

Eigen::Ref< const VectorX< T > >	GetVelocities (const systems::Context< T > &context) const
	Returns the current value in the given `context` of the generalized velocities v for this joint. More...

void	SetDefaultPose (const math::RigidTransform< double > &X_FM)
	Sets this joint's default generalized positions q₀ such that the pose of the child frame M in the parent frame F best matches the given pose. More...

math::RigidTransform< double >	GetDefaultPose () const
	Returns this joint's default pose as a RigidTransform X_FM. More...

void	SetPose (systems::Context< T > *context, const math::RigidTransform< T > &X_FM) const
	Sets in the given `context` this joint's generalized positions q such that the pose of the child frame M in the parent frame F best matches the given pose. More...

math::RigidTransform< T >	GetPose (const systems::Context< T > &context) const
	Returns this joint's current pose using its position coordinates q taken from the given `context` and converting that to a RigidTransform X_FM(q). More...

void	SetSpatialVelocity (systems::Context< T > *context, const SpatialVelocity< T > &V_FM) const
	Sets in the given `context` this joint's generalized velocities v such that the spatial velocity of the child frame M in the parent frame F best matches the given spatial velocity. More...

SpatialVelocity< T >	GetSpatialVelocity (const systems::Context< T > &context) const
	Given the generalized positions q and generalized velocities v for this joint in the given `context`, returns the cross-joint spatial velocity V_FM. More...

void	SetDefaultPosePair (const Quaternion< double > &q_FM, const Vector3< double > &p_FM)
	(Advanced) This is the same as SetDefaultPose() except it takes the pose as a (quaternion, translation vector) pair. More...

std::pair< Eigen::Quaternion< double >, Vector3< double > >	GetDefaultPosePair () const
	(Advanced) This is the same as GetDefaultPose() except it returns this joint's default pose as a (quaternion, translation vector) pair. More...

void	SetPosePair (systems::Context< T > *context, const Quaternion< T > &q_FM, const Vector3< T > &p_FM) const
	(Advanced) This is the same as SetPose() except it takes the pose as a (quaternion, translation vector) pair. More...

std::pair< Eigen::Quaternion< T >, Vector3< T > >	GetPosePair (const systems::Context< T > &context) const
	(Advanced) This is the same as GetPose() except it returns this joint's pose in the given `context` as a (quaternion, translation vector) pair. More...

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 = void>
const MultibodyPlant< T > &	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

Static Public Attributes
static const char	kTypeName [] = "weld"

Protected Member Functions
void	DoAddInOneForce (const systems::Context< T > &, int, const T &, MultibodyForces< T > *) const override
	Joint<T> override called through public NVI, Joint::AddInForce(). More...

Protected Member Functions inherited from Joint< T >
virtual void	DoSetDefaultPosePair (const Quaternion< double > &q_FM, const Vector3< double > &p_FM)
	Implementation of the NVI SetDefaultPose(). More...

virtual std::pair< Eigen::Quaternion< double >, Vector3< double > >	DoGetDefaultPosePair () const
	Implementation of the NVI GetDefaultPose(). More...

virtual const T &	DoGetOnePosition (const systems::Context< T > &) const
	Implementation of the NVI GetOnePosition() that must only be implemented by those joint subclasses that have a single degree of freedom. More...

virtual const T &	DoGetOneVelocity (const systems::Context< T > &) const
	Implementation of the NVI GetOneVelocity() that must only be implemented by those joint subclasses that have a single degree of freedom. More...

virtual void	DoAddInDamping (const systems::Context< T > &, MultibodyForces< T > *) const
	Adds into MultibodyForces the forces due to damping within `this` joint. More...

void	DoSetTopology (const internal::MultibodyTreeTopology &) override
	Implementation of the NVI SetTopology(). More...

const JointImplementation &	get_implementation () const
	Returns a const reference to the internal implementation of `this` joint. More...

bool	has_implementation () const
	Returns whether `this` joint owns a particular implementation. More...

std::pair< const Frame< T > , const Frame< T > >	tree_frames (bool use_reversed_mobilizer) const
	Utility for concrete joint implementations to use to select the inboard/outboard frames for a tree in the spanning forest, given whether they should be reversed from the parent/child frames that are members of this Joint object. More...

template<template< typename > class ConcreteMobilizer>
const ConcreteMobilizer< T > &	get_mobilizer_downcast () const
	(Internal use only) Returns the mobilizer implementing this joint, downcast to its specific type. More...

template<template< typename > class ConcreteMobilizer>
ConcreteMobilizer< T > &	get_mutable_mobilizer_downcast ()
	(Internal use only) Mutable flavor of get_mobilizer_downcast(). More...

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
template<typename >
class	WeldJoint

Member Typedef Documentation

◆ Context

using Context = systems::Context<Scalar>

Constructor & Destructor Documentation

◆ WeldJoint() [1/3]

WeldJoint ( const WeldJoint< T > & )

delete

◆ WeldJoint() [2/3]

WeldJoint ( WeldJoint< T > && )

delete

◆ WeldJoint() [3/3]

WeldJoint	(	const std::string &	name,
		const Frame< T > &	frame_on_parent_F,
		const Frame< T > &	frame_on_child_M,
		const math::RigidTransform< double > &	X_FM
	)

Constructor for a WeldJoint between a frame_on_parent_F and a frame_on_child_M so that their relative pose X_FM is fixed as if they were "welded" together.

◆ ~WeldJoint()

~WeldJoint ( )

override

Member Function Documentation

◆ DoAddInOneForce()

void DoAddInOneForce	(	const systems::Context< T > &	,
		int	,
		const T &	,
		MultibodyForces< T > *
	)		const

overrideprotectedvirtual

Joint<T> override called through public NVI, Joint::AddInForce().

Since frame F and M are welded together, it is physically not possible to apply forces between them. Therefore this method throws an exception if invoked.

Implements Joint< T >.

◆ operator=() [1/2]

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

delete

◆ operator=() [2/2]

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

delete

◆ type_name()

const std::string& type_name ( ) const

overridevirtual

Returns a string identifying the type of this joint, such as "revolute" or "prismatic".

Implements Joint< T >.

◆ X_FM()

const math::RigidTransform<double>& X_FM ( ) const

Returns the pose X_FM of frame M in F.

Friends And Related Function Documentation

◆ WeldJoint

friend class WeldJoint

friend

Member Data Documentation

◆ kTypeName

const char kTypeName = "weld"

static

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

drake/multibody/tree/weld_joint.h

Detailed Description

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

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Friends

Member Typedef Documentation

◆ Context

Constructor & Destructor Documentation

◆ WeldJoint() [1/3]

◆ WeldJoint() [2/3]

◆ WeldJoint() [3/3]

◆ ~WeldJoint()

Member Function Documentation

◆ DoAddInOneForce()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ type_name()

◆ X_FM()

Friends And Related Function Documentation

◆ WeldJoint

Member Data Documentation

◆ kTypeName

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