Detailed Description

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

This Joint allows two bodies to move freely relatively to one another.

That is, given a frame F attached to the parent body P and a frame M attached to the child body B (see the Joint class's documentation), this Joint allows frame M to translate and rotate freely with respect to F, introducing six degrees of freedom. This Joint introduces four generalized positions to describe the orientation R_FM of frame M in F with a quaternion q_FM, and three generalized positions to describe the translation of frame M's origin in F with a position vector p_FM. The seven entries of the configuration vector q are ordered (q_FM, p_FM) with the quaternion, ordered wxyz (scalar then vector), preceding the translation vector. As generalized velocities, this Joint introduces the angular velocity w_FM of frame M in F and the linear velocity v_FM of frame M's origin in frame F, ordered (w_FM, v_FM).

Template Parameters

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

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

Public Member Functions
	QuaternionFloatingJoint (const std::string &name, const Frame< T > &frame_on_parent, const Frame< T > &frame_on_child, double angular_damping=0.0, double translational_damping=0.0)
	Constructor for a QuaternionFloatingJoint granting six degrees of freedom to an outboard frame M attached to the child body B with respect to an inboard frame F attached to the parent body P. More...

	~QuaternionFloatingJoint () override

const std::string &	type_name () const override
	Returns the name of this joint type: "quaternion_floating". More...

double	default_angular_damping () const
	Returns `this` joint's default angular damping constant in N⋅m⋅s. More...

double	default_translational_damping () const
	Returns `this` joint's default translational damping constant in N⋅s/m. More...

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

QuaternionFloatingJoint &	operator= (const QuaternionFloatingJoint &)=delete

	QuaternionFloatingJoint (QuaternionFloatingJoint &&)=delete

QuaternionFloatingJoint &	operator= (QuaternionFloatingJoint &&)=delete

Context-dependent value access
Quaternion< T >	get_quaternion (const systems::Context< T > &context) const
	Gets the quaternion `q_FM` that represents the orientation of outboard frame M in the inboard frame F. More...

Vector3< T >	get_translation (const systems::Context< T > &context) const
	Returns the position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in inboard frame F. More...

math::RigidTransform< T >	GetPose (const systems::Context< T > &context) const
	Returns the pose `X_FM` of the outboard frame M as measured and expressed in the inboard frame F. More...

Vector3< T >	get_angular_velocity (const systems::Context< T > &context) const
	Retrieves from `context` the angular velocity `w_FM` of the child frame M in the parent frame F, expressed in F. More...

Vector3< T >	get_translational_velocity (const systems::Context< T > &context) const
	Retrieves from `context` the translational velocity `v_FM` of the child frame M's origin as measured and expressed in the parent frame F. More...

Context-dependent value setters
const QuaternionFloatingJoint< T > &	SetQuaternion (systems::Context< T > *context, const Quaternion< T > &q_FM) const
	Sets `context` so that the orientation of frame M in F is given by the input quaternion `q_FM`. More...

const QuaternionFloatingJoint< T > &	SetOrientation (systems::Context< T > *context, const math::RotationMatrix< T > &R_FM) const
	Sets the quaternion in `context` so this joint's orientation is consistent with the given `R_FM` rotation matrix. More...

const QuaternionFloatingJoint< T > &	SetTranslation (systems::Context< T > *context, const Vector3< T > &p_FM) const
	For this joint, stores the position vector `p_FM` in `context`. More...

const QuaternionFloatingJoint< T > &	SetPose (systems::Context< T > *context, const math::RigidTransform< T > &X_FM) const
	Sets `context` to store `X_FM` the pose of frame M measured and expressed in frame F. More...

const QuaternionFloatingJoint< T > &	set_angular_velocity (systems::Context< T > *context, const Vector3< T > &w_FM) const
	Sets in `context` the state for `this` joint so that the angular velocity of the child frame M in the parent frame F is `w_FM`. More...

const QuaternionFloatingJoint< T > &	set_translational_velocity (systems::Context< T > *context, const Vector3< T > &v_FM) const
	Sets in `context` the state for `this` joint so that the translational velocity of the child frame M's origin in the parent frame F is `v_FM`. More...

Random distribution setters
void	set_random_translation_distribution (const Vector3< symbolic::Expression > &p_FM)
	For this joint, sets the random distribution that the translation of this joint will be randomly sampled from. More...

void	set_random_quaternion_distribution (const Eigen::Quaternion< symbolic::Expression > &q_FM)
	(Advanced) Sets the random distribution that the orientation of this joint will be randomly sampled from. More...

void	set_random_quaternion_distribution_to_uniform ()
	Sets the random distribution such that the orientation of this joint will be randomly sampled using uniformly sampled rotations. More...

Default value getters
Quaternion< double >	get_default_quaternion () const
	Gets the default quaternion `q_FM` for `this` joint. More...

Vector3< double >	get_default_translation () const
	Returns this joint's default translation as the position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in inboard frame F. More...

Default value setters
void	set_default_quaternion (const Quaternion< double > &q_FM)
	Sets the default quaternion `q_FM` of this joint. More...

void	set_default_translation (const Vector3< double > &p_FM)
	Sets this joint's default position vector `p_FM`. More...

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 [] = "quaternion_floating"
	The name for this Joint type. It resolves to "quaternion_floating". More...

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...

void	DoAddInDamping (const systems::Context< T > &context, MultibodyForces< T > *forces) const override
	Joint<T> override called through public NVI, Joint::AddInDamping(). More...

Protected Member Functions inherited from Joint< T >
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...

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	QuaternionFloatingJoint

Constructor & Destructor Documentation

◆ QuaternionFloatingJoint() [1/3]

QuaternionFloatingJoint ( const QuaternionFloatingJoint< T > & )

delete

◆ QuaternionFloatingJoint() [2/3]

QuaternionFloatingJoint ( QuaternionFloatingJoint< T > && )

delete

◆ QuaternionFloatingJoint() [3/3]

QuaternionFloatingJoint	(	const std::string &	name,
		const Frame< T > &	frame_on_parent,
		const Frame< T > &	frame_on_child,
		double	angular_damping = `0.0`,
		double	translational_damping = `0.0`
	)

Constructor for a QuaternionFloatingJoint granting six degrees of freedom to an outboard frame M attached to the child body B with respect to an inboard frame F attached to the parent body P.

The orientation of frame M in F is represented by a quaternion q_FM while the position of F in M is given by a position vector p_FM expressed in frame F. See this class's documentation for further details on the definition of these frames, get_quaternion() and get_translation() for an explanation of the configuration of this joint, and get_angular_velocity() and get_translational_velocity() for an explanation of the generalized velocities.

This constructor signature creates a joint with no joint limits, i.e. the joint position, velocity and acceleration limits are the pair (-∞, ∞). These can be set using the Joint methods set_position_limits(), set_velocity_limits() and set_acceleration_limits().

The first three arguments to this constructor are those of the Joint class constructor. See the Joint class's documentation for details. The additional parameters are:

Parameters

[in]	angular_damping	Viscous damping coefficient in N⋅m⋅s for the angular component of this joint's velocity, used to model losses within the joint. See documentation of default_angular_damping() for details on modelling of the damping force.
[in]	translational_damping	Viscous damping coefficient in N⋅s/m for the translational component of this joint's velocity, used to model losses within the joint. See documentation of default_translational_damping() for details on modelling of the damping force.

Exceptions

std::exception	if angular_damping is negative.
std::exception	if translational_damping is negative.

◆ ~QuaternionFloatingJoint()

~QuaternionFloatingJoint ( )

override

Member Function Documentation

◆ default_angular_damping()

double default_angular_damping ( ) const

Returns this joint's default angular damping constant in N⋅m⋅s.

The damping torque (in N⋅m) is modeled as τ = -damping⋅ω, i.e. opposing motion, with ω the angular velocity of frame M in F (see get_angular_velocity()) and τ the torque on child body B (to which M is rigidly attached).

◆ default_translational_damping()

double default_translational_damping ( ) const

Returns this joint's default translational damping constant in N⋅s/m.

The damping force (in N) is modeled as f = -damping⋅v i.e. opposing motion, with v the translational velocity of frame M in F (see get_translational_velocity()) and f the force on child body B at Mo.

◆ DoAddInDamping()

void DoAddInDamping	(	const systems::Context< T > &	context,
		MultibodyForces< T > *	forces
	)		const

overrideprotectedvirtual

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

Therefore arguments were already checked to be valid. This method adds into the translational component of forces for this joint a dissipative force according to the viscous law f = -d⋅v, with d the damping coefficient (see default_translational_damping()). This method also adds into the angular component of forces for this joint a dissipative torque according to the viscous law τ = -d⋅ω, with d the damping coefficient (see default_angular_damping()).

Reimplemented from Joint< T >.

◆ DoAddInOneForce()

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

overrideprotectedvirtual

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

Adding forces per-dof makes no physical sense. Therefore, this method throws an exception if invoked.

Implements Joint< T >.

◆ get_angular_velocity()

Vector3<T> get_angular_velocity ( const systems::Context< T > & context ) const

Retrieves from context the angular velocity w_FM of the child frame M in the parent frame F, expressed in F.

Parameters

[in] context A Context for the MultibodyPlant this joint belongs to.

Return values

w_FM	A vector in ℝ³ with the angular velocity of the child frame M in the parent frame F, expressed in F. Refer to this class's documentation for further details and definitions of these frames.

◆ get_default_quaternion()

Quaternion<double> get_default_quaternion ( ) const

Gets the default quaternion q_FM for this joint.

Returns: The default quaternion q_FM of this.

◆ get_default_translation()

Vector3<double> get_default_translation ( ) const

Returns this joint's default translation as the position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in inboard frame F.

Return values

This	joint's default translation as the position vector p_FM.

◆ get_quaternion()

Quaternion<T> get_quaternion ( const systems::Context< T > & context ) const

Gets the quaternion q_FM that represents the orientation of outboard frame M in the inboard frame F.

Refer to the documentation for this class for details.

Parameters

[in] context A Context for the MultibodyPlant this joint belongs to.

Return values

q_FM	The quaternion representing the orientation of frame M in F.

◆ get_translation()

Vector3<T> get_translation ( const systems::Context< T > & context ) const

Returns the position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in inboard frame F.

Parameters

[in] context contains the state of the multibody system.

Note: Class documentation describes inboard frame F and outboard frame M.

Return values

p_FM	The position vector from Fo (frame F's origin) to Mo (frame M's origin), expressed in frame F.

◆ get_translational_velocity()

Vector3<T> get_translational_velocity ( const systems::Context< T > & context ) const

Retrieves from context the translational velocity v_FM of the child frame M's origin as measured and expressed in the parent frame F.

Parameters

[in] context A Context for the MultibodyPlant this joint belongs to.

Return values

v_FM	A vector in ℝ³ with the translational velocity of the origin of child frame M in the parent frame F, expressed in F. Refer to this class's documentation for further details and definitions of these frames.

◆ GetPose()

math::RigidTransform<T> GetPose ( const systems::Context< T > & context ) const

Returns the pose X_FM of the outboard frame M as measured and expressed in the inboard frame F.

Refer to the documentation for this class for details.

Parameters

[in] context A Context for the MultibodyPlant this joint belongs to.

Return values

X_FM	The pose of frame M in frame F.

◆ operator=() [1/2]

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

delete

◆ operator=() [2/2]

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

delete

◆ set_angular_velocity()

const QuaternionFloatingJoint<T>& set_angular_velocity	(	systems::Context< T > *	context,
		const Vector3< T > &	w_FM
	)		const

Sets in context the state for this joint so that the angular velocity of the child frame M in the parent frame F is w_FM.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	w_FM	A vector in ℝ³ with the angular velocity of the child frame M in the parent frame F, expressed in F. Refer to this class's documentation for further details and definitions of these frames.

Returns: a constant reference to this joint.

◆ set_default_quaternion()

void set_default_quaternion ( const Quaternion< double > & q_FM )

Sets the default quaternion q_FM of this joint.

Parameters

[in] q_FM The desired default quaternion of the joint.

◆ set_default_translation()

void set_default_translation ( const Vector3< double > & p_FM )

Sets this joint's default position vector p_FM.

Parameters

[in] p_FM position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in frame F.

◆ set_random_quaternion_distribution()

void set_random_quaternion_distribution ( const Eigen::Quaternion< symbolic::Expression > & q_FM )

(Advanced) Sets the random distribution that the orientation of this joint will be randomly sampled from.

If a translation (position) distribution has already been set with stochastic variables, it will remain so. Otherwise translation will be set to this joint's zero configuration. See get_quaternion() for details on the orientation representation.

Note: Use caution when setting a quaternion distribution. A naive uniform sampling of each component will not lead to a uniform sampling of the unit sphere. See set_random_quaternion_distribution_to_uniform() for the most common case of uniformly sampling rotations.

◆ set_random_quaternion_distribution_to_uniform()

void set_random_quaternion_distribution_to_uniform ( )

Sets the random distribution such that the orientation of this joint will be randomly sampled using uniformly sampled rotations.

◆ set_random_translation_distribution()

void set_random_translation_distribution ( const Vector3< symbolic::Expression > & p_FM )

For this joint, sets the random distribution that the translation of this joint will be randomly sampled from.

If a quaternion distribution has already been set with stochastic variables, it will remain so. Otherwise the quaternion will be set to this joint's zero orientation. See get_translation() for details on the translation representation.

◆ set_translational_velocity()

const QuaternionFloatingJoint<T>& set_translational_velocity	(	systems::Context< T > *	context,
		const Vector3< T > &	v_FM
	)		const

Sets in context the state for this joint so that the translational velocity of the child frame M's origin in the parent frame F is v_FM.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	w_FM	A vector in ℝ³ with the translational velocity of the child frame M's origin in the parent frame F, expressed in F. Refer to this class's documentation for further details and definitions of these frames.

Returns: a constant reference to this joint.

◆ SetOrientation()

const QuaternionFloatingJoint<T>& SetOrientation	(	systems::Context< T > *	context,
		const math::RotationMatrix< T > &	R_FM
	)		const

Sets the quaternion in context so this joint's orientation is consistent with the given R_FM rotation matrix.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	R_FM	The rotation matrix relating the orientation of frame F and frame M.

Returns: a constant reference to this joint.

◆ SetPose()

const QuaternionFloatingJoint<T>& SetPose	(	systems::Context< T > *	context,
		const math::RigidTransform< T > &	X_FM
	)		const

Sets context to store X_FM the pose of frame M measured and expressed in frame F.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	X_FM	The desired pose of frame M in frame F to be stored in `context`.

Returns: a constant reference to this joint.

◆ SetQuaternion()

const QuaternionFloatingJoint<T>& SetQuaternion	(	systems::Context< T > *	context,
		const Quaternion< T > &	q_FM
	)		const

Sets context so that the orientation of frame M in F is given by the input quaternion q_FM.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	q_FM	Quaternion relating frames F and M to be stored in `context`.

Returns: a constant reference to this joint.

◆ SetTranslation()

const QuaternionFloatingJoint<T>& SetTranslation	(	systems::Context< T > *	context,
		const Vector3< T > &	p_FM
	)		const

For this joint, stores the position vector p_FM in context.

Parameters

[in,out]	context	A Context for the MultibodyPlant this joint belongs to.
[in]	p_FM	position vector p_FoMo_F from Fo (inboard frame F's origin) to Mo (outboard frame M's origin), expressed in frame F.

Returns: a constant reference to this joint.

◆ type_name()

const std::string& type_name ( ) const

overridevirtual

Returns the name of this joint type: "quaternion_floating".

Implements Joint< T >.

Friends And Related Function Documentation

◆ QuaternionFloatingJoint

friend class QuaternionFloatingJoint

friend

Member Data Documentation

◆ kTypeName

const char kTypeName = "quaternion_floating"

static

The name for this Joint type. It resolves to "quaternion_floating".

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

drake/multibody/tree/quaternion_floating_joint.h

Detailed Description

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

Public Member Functions

Static Public Attributes

Protected Member Functions

Friends

Constructor & Destructor Documentation

◆ QuaternionFloatingJoint() [1/3]

◆ QuaternionFloatingJoint() [2/3]

◆ QuaternionFloatingJoint() [3/3]

◆ ~QuaternionFloatingJoint()

Member Function Documentation

◆ default_angular_damping()

◆ default_translational_damping()

◆ DoAddInDamping()

◆ DoAddInOneForce()

◆ get_angular_velocity()

◆ get_default_quaternion()

◆ get_default_translation()

◆ get_quaternion()

◆ get_translation()

◆ get_translational_velocity()

◆ GetPose()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ set_angular_velocity()

◆ set_default_quaternion()

◆ set_default_translation()

◆ set_random_quaternion_distribution()

◆ set_random_quaternion_distribution_to_uniform()

◆ set_random_translation_distribution()

◆ set_translational_velocity()

◆ SetOrientation()

◆ SetPose()

◆ SetQuaternion()

◆ SetTranslation()

◆ type_name()

Friends And Related Function Documentation

◆ QuaternionFloatingJoint

Member Data Documentation

◆ kTypeName

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