Detailed Description

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

This Joint allows two bodies to rotate relatively to one another around a common axis.

That is, given a frame Jp attached to the parent body P and a frame Jc attached to the child body C (see the Joint class's documentation), this Joint allows frames Jp and Jc to rotate with respect to each other about an axis â. The rotation angle's sign is defined such that child body C rotates about axis â according to the right hand rule, with thumb aligned in the axis direction. Axis vector â is constant and has the same components in both frames Jp and Jc, that is, â_Jp = â_Jc.

Template Parameters

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

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

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

Public Member Functions
	RevoluteJoint (const std::string &name, const Frame< T > &frame_on_parent, const Frame< T > &frame_on_child, const Vector3< double > &axis, double damping=0)
	Constructor to create a revolute joint between two bodies so that frame Jp attached to the parent body P and frame Jc attached to the child body C, rotate relatively to one another about a common axis. More...

	RevoluteJoint (const std::string &name, const Frame< T > &frame_on_parent, const Frame< T > &frame_on_child, const Vector3< double > &axis, double pos_lower_limit, double pos_upper_limit, double damping=0)
	Constructor to create a revolute joint between two bodies so that frame Jp attached to the parent body P and frame Jc attached to the child body C, rotate relatively to one another about a common axis. More...

	~RevoluteJoint () final

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

const Vector3< double > &	revolute_axis () const
	Returns the axis of revolution of `this` joint as a unit vector. More...

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

void	set_default_damping (double damping)
	Sets the default value of viscous damping for this joint, in N⋅m⋅s. More...

double	position_lower_limit () const
	Returns the position lower limit for `this` joint in radians. More...

double	position_upper_limit () const
	Returns the position upper limit for `this` joint in radians. More...

double	velocity_lower_limit () const
	Returns the velocity lower limit for `this` joint in radians / s. More...

double	velocity_upper_limit () const
	Returns the velocity upper limit for `this` joint in radians / s. More...

double	acceleration_lower_limit () const
	Returns the acceleration lower limit for `this` joint in radians / s². More...

double	acceleration_upper_limit () const
	Returns the acceleration upper limit for `this` joint in radians / s². More...

double	get_default_angle () const
	Gets the default rotation angle. More...

void	set_default_angle (double angle)
	Sets the `default_positions` of this joint (in this case a single angle). More...

void	AddInTorque (const systems::Context< T > &context, const T &torque, MultibodyForces< T > *forces) const
	Adds into `forces` a given `torque` for `this` joint that is to be applied about the joint's axis. More...

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

RevoluteJoint &	operator= (const RevoluteJoint &)=delete

	RevoluteJoint (RevoluteJoint &&)=delete

RevoluteJoint &	operator= (RevoluteJoint &&)=delete

Context-dependent value access
const T &	get_angle (const Context< T > &context) const
	Gets the rotation angle of `this` mobilizer from `context`. More...

const RevoluteJoint< T > &	set_angle (Context< T > *context, const T &angle) const
	Sets the `context` so that the generalized coordinate corresponding to the rotation angle of `this` joint equals `angle`. More...

void	set_random_angle_distribution (const symbolic::Expression &angle)

const T &	get_angular_rate (const Context< T > &context) const
	Gets the rate of change, in radians per second, of `this` joint's angle (see get_angle()) from `context`. More...

const RevoluteJoint< T > &	set_angular_rate (Context< T > *context, const T &angle) const
	Sets the rate of change, in radians per second, of this `this` joint's angle to `angle`. More...

const T &	GetDamping (const Context< T > &context) const
	Returns the Context dependent damping coefficient stored as a parameter in `context`. More...

void	SetDamping (Context< T > *context, const T &damping) const
	Sets the value of the viscous damping coefficient for this joint, stored as a parameter in `context`. 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...

JointOrdinal	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...

void	DeclareDiscreteState (internal::MultibodyTreeSystem< T > *tree_system)
	Declares MultibodyTreeSystem discrete states. More...

void	DeclareCacheEntries (internal::MultibodyTreeSystem< T > *tree_system)
	(Advanced) Declares all cache entries needed by this element. More...

bool	is_ephemeral () const
	Returns `true` if this MultibodyElement was added during Finalize() rather than something a user added. More...

void	set_is_ephemeral (bool is_ephemeral)
	(Internal use only) Sets the `is_ephemeral` flag to the indicated value. More...

	MultibodyElement (const MultibodyElement &)=delete

MultibodyElement &	operator= (const MultibodyElement &)=delete

	MultibodyElement (MultibodyElement &&)=delete

MultibodyElement &	operator= (MultibodyElement &&)=delete

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

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

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

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

bool	has_mobilizer () const
	(Internal use only) Returns true if this Joint has an implementing Mobilizer. 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...

template<typename ElementOrdinalType = int64_t>
ElementOrdinalType	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...

virtual void	DoDeclareDiscreteState (internal::MultibodyTreeSystem< T > *)
	Implementation of the NVI DeclareDiscreteState(). More...

virtual void	DoDeclareCacheEntries (internal::MultibodyTreeSystem< T > *)
	Derived classes must override this method to declare cache entries needed by `this` element. 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...

systems::DiscreteStateIndex	DeclareDiscreteState (internal::MultibodyTreeSystem< T > *tree_system, const VectorX< T > &model_value)
	To be used by MultibodyElement-derived objects when declaring discrete states in their implementation of DoDeclareDiscreteStates(). More...

systems::CacheEntry &	DeclareCacheEntry (internal::MultibodyTreeSystem< T > *tree_system, std::string description, systems::ValueProducer value_producer, std::set< systems::DependencyTicket > prerequisites_of_calc)
	To be used by MultibodyElement-derived objects when declaring cache entries in their implementation of DoDeclareCacheEntries(). More...

bool	has_parent_tree () const
	Returns true if this multibody element has a parent tree, otherwise false. More...

Friends
template<typename >
class	RevoluteJoint

class	JointTester

Member Typedef Documentation

◆ Context

using Context = systems::Context<Scalar>

Constructor & Destructor Documentation

◆ RevoluteJoint() [1/4]

RevoluteJoint ( const RevoluteJoint< T > & )

delete

◆ RevoluteJoint() [2/4]

RevoluteJoint ( RevoluteJoint< T > && )

delete

◆ RevoluteJoint() [3/4]

RevoluteJoint	(	const std::string &	name,
		const Frame< T > &	frame_on_parent,
		const Frame< T > &	frame_on_child,
		const Vector3< double > &	axis,
		double	damping = `0`
	)

Constructor to create a revolute joint between two bodies so that frame Jp attached to the parent body P and frame Jc attached to the child body C, rotate relatively to one another about a common axis.

See this class's documentation for further details on the definition of these frames and rotation angle. This constructor signature creates a joint with no joint limits, i.e. the joint position, velocity and acceleration limits are the pair (-∞, ∞). 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]	axis	A vector in ℝ³ specifying the axis of revolution for this joint. Given that frame Jc only rotates with respect to Jp and their origins are coincident at all times, the components of `axis` in either frame Jp or Jc are exactly the same, that is, `axis_Jp = axis_Jc`. In other words, `axis_Jp` (or `axis_Jc`) is the eigenvector of `R_JpJc` with eigenvalue equal to one. This vector can have any length, only the direction is used. This method aborts if `axis` is the zero vector.
[in]	damping	Viscous damping coefficient, in N⋅m⋅s, used to model losses within the joint. The damping torque (in N⋅m) is modeled as `τ = -damping⋅ω`, i.e. opposing motion, with ω the angular rate for `this` joint (see get_angular_rate()).

Exceptions

std::exception if damping is negative.

◆ RevoluteJoint() [4/4]

RevoluteJoint	(	const std::string &	name,
		const Frame< T > &	frame_on_parent,
		const Frame< T > &	frame_on_child,
		const Vector3< double > &	axis,
		double	pos_lower_limit,
		double	pos_upper_limit,
		double	damping = `0`
	)

Constructor to create a revolute joint between two bodies so that frame Jp attached to the parent body P and frame Jc attached to the child body C, rotate relatively to one another about a common axis.

See this class's documentation for further details on the definition of these frames and rotation angle. 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]	axis	A vector in ℝ³ specifying the axis of revolution for this joint. Given that frame Jc only rotates with respect to Jp and their origins are coincident at all times, the components of `axis` in either frame Jp or Jc are exactly the same, that is, `axis_Jp = axis_Jc`. In other words, `axis_Jp` (or `axis_Jc`) is the eigenvector of `R_JpJc` with eigenvalue equal to one. This vector can have any length, only the direction is used.
[in]	pos_lower_limit	Lower position limit, in radians, for the rotation coordinate (see get_angle()).
[in]	pos_upper_limit	Upper position limit, in radians, for the rotation coordinate (see get_angle()).
[in]	damping	Viscous damping coefficient, in N⋅m⋅s, used to model losses within the joint. The damping torque (in N⋅m) is modeled as `τ = -damping⋅ω`, i.e. opposing motion, with ω the angular rate for `this` joint (see get_angular_rate()).

Exceptions

std::exception	if the L2 norm of `axis` is less than the square root of machine epsilon.
std::exception	if damping is negative.
std::exception	if pos_lower_limit > pos_upper_limit.

◆ ~RevoluteJoint()

~RevoluteJoint ( )

final

Member Function Documentation

◆ acceleration_lower_limit()

double acceleration_lower_limit ( ) const

Returns the acceleration lower limit for this joint in radians / s².

◆ acceleration_upper_limit()

double acceleration_upper_limit ( ) const

Returns the acceleration upper limit for this joint in radians / s².

◆ AddInTorque()

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

Adds into forces a given torque for this joint that is to be applied about the joint's axis.

The torque is defined to be positive according to the right-hand-rule with the thumb aligned in the direction of this joint's axis. That is, a positive torque causes a positive rotational acceleration according to the right-hand-rule around the joint's axis.

Note: A torque is the moment of a set of forces whose resultant is zero.

◆ default_damping()

double default_damping ( ) const

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

◆ DoAddInDamping()

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

finalprotectedvirtual

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

Therefore arguments were already checked to be valid. This method adds into forces a dissipative torque according to the viscous law τ = -d⋅ω, with d the damping coefficient (see default_damping()).

Reimplemented from Joint< T >.

◆ DoAddInOneForce()

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

finalprotectedvirtual

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

Therefore arguments were already checked to be valid. For a RevoluteJoint, we must always have joint_dof = 0 since there is only a single degree of freedom (num_velocities() == 1). joint_tau is the torque applied about the joint's axis, on the body declared as child (according to the revolute joint's constructor) at the origin of the child frame (which is coincident with the origin of the parent frame at all times). The torque is defined to be positive according to the right-hand-rule with the thumb aligned in the direction of this joint's axis. That is, a positive torque causes a positive rotational acceleration (of the child body frame) according to the right-hand-rule around the joint's axis.

Implements Joint< T >.

◆ get_angle()

const T& get_angle ( const Context< T > & context ) const

Gets the rotation angle of this mobilizer from context.

Parameters

[in] context The context of the MultibodyTree this joint belongs to.

Returns: The angle coordinate of this joint stored in the context.

◆ get_angular_rate()

const T& get_angular_rate ( const Context< T > & context ) const

Gets the rate of change, in radians per second, of this joint's angle (see get_angle()) from context.

Parameters

[in] context The context of the MultibodyTree this joint belongs to.

Returns: The rate of change of this joint's angle as stored in the context.

◆ get_default_angle()

double get_default_angle ( ) const

Gets the default rotation angle.

Wrapper for the more general Joint::default_positions().

Returns: The default angle of this stored in default_positions_

◆ GetDamping()

const T& GetDamping ( const Context< T > & context ) const

Returns the Context dependent damping coefficient stored as a parameter in context.

Refer to default_damping() for details.

Parameters

[in] context The context storing the state and parameters for the model to which this joint belongs.

◆ operator=() [1/2]

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

delete

◆ operator=() [2/2]

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

delete

◆ position_lower_limit()

double position_lower_limit ( ) const

Returns the position lower limit for this joint in radians.

◆ position_upper_limit()

double position_upper_limit ( ) const

Returns the position upper limit for this joint in radians.

◆ revolute_axis()

const Vector3<double>& revolute_axis ( ) const

Returns the axis of revolution of this joint as a unit vector.

Since the measures of this axis in either frame F or M are the same (see this class's documentation for frame definitions) then, axis = axis_Jp = axis_Jc.

◆ set_angle()

const RevoluteJoint<T>& set_angle	(	Context< T > *	context,
		const T &	angle
	)		const

Sets the context so that the generalized coordinate corresponding to the rotation angle of this joint equals angle.

Parameters

[in]	context	The context of the MultibodyTree this joint belongs to.
[in]	angle	The desired angle in radians to be stored in `context`.

Returns: a constant reference to this joint.

◆ set_angular_rate()

const RevoluteJoint<T>& set_angular_rate	(	Context< T > *	context,
		const T &	angle
	)		const

Sets the rate of change, in radians per second, of this this joint's angle to angle.

The new rate of change angle gets stored in context.

Parameters

[in]	context	The context of the MultibodyTree this joint belongs to.
[in]	angle	The desired rate of change of `this` joints's angle in radians per second. (Should have been named `rate` or `angular_rate`.)

Returns: a constant reference to this joint.

◆ set_default_angle()

void set_default_angle ( double angle )

Sets the default_positions of this joint (in this case a single angle).

Parameters

[in] angle The desired default angle of the joint

◆ set_default_damping()

void set_default_damping ( double damping )

Sets the default value of viscous damping for this joint, in N⋅m⋅s.

Exceptions

std::exception	if damping is negative.
std::exception	if this element is not associated with a MultibodyPlant.

Precondition: the MultibodyPlant must not be finalized.

◆ set_random_angle_distribution()

void set_random_angle_distribution ( const symbolic::Expression & angle )

◆ SetDamping()

void SetDamping	(	Context< T > *	context,
		const T &	damping
	)		const

Sets the value of the viscous damping coefficient for this joint, stored as a parameter in context.

Refer to default_damping() for details.

Parameters

[out]	context	The context storing the state and parameters for the model to which `this` joint belongs.
[in]	damping	The damping value.

Exceptions

std::exception if damping is negative.

◆ type_name()

const std::string& type_name ( ) const

finalvirtual

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

Implements Joint< T >.

◆ velocity_lower_limit()

double velocity_lower_limit ( ) const

Returns the velocity lower limit for this joint in radians / s.

◆ velocity_upper_limit()

double velocity_upper_limit ( ) const

Returns the velocity upper limit for this joint in radians / s.

Friends And Related Function Documentation

◆ JointTester

friend class JointTester

friend

◆ RevoluteJoint

friend class RevoluteJoint

friend

Member Data Documentation

◆ kTypeName

const char kTypeName = "revolute"

static

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

drake/multibody/tree/revolute_joint.h

Detailed Description

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

Public Types

Public Member Functions

Static Public Attributes

Protected Member Functions

Friends

Member Typedef Documentation

◆ Context

Constructor & Destructor Documentation

◆ RevoluteJoint() [1/4]

◆ RevoluteJoint() [2/4]

◆ RevoluteJoint() [3/4]

◆ RevoluteJoint() [4/4]

◆ ~RevoluteJoint()

Member Function Documentation

◆ acceleration_lower_limit()

◆ acceleration_upper_limit()

◆ AddInTorque()

◆ default_damping()

◆ DoAddInDamping()

◆ DoAddInOneForce()

◆ get_angle()

◆ get_angular_rate()

◆ get_default_angle()

◆ GetDamping()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ position_lower_limit()

◆ position_upper_limit()

◆ revolute_axis()

◆ set_angle()

◆ set_angular_rate()

◆ set_default_angle()

◆ set_default_damping()

◆ set_random_angle_distribution()

◆ SetDamping()

◆ type_name()

◆ velocity_lower_limit()

◆ velocity_upper_limit()

Friends And Related Function Documentation

◆ JointTester

◆ RevoluteJoint

Member Data Documentation

◆ kTypeName

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