Robot joint. More...

#include <hpp/model/joint.hh>

Inheritance diagram for hpp::model::Joint:

Collaboration diagram for hpp::model::Joint:

Public Member Functions
const Transform3f &	initialPosition () const
	Joint initial position (when robot is in zero configuration)
const Transform3f &	currentTransformation () const
	Joint transformation.
virtual void	computePosition (ConfigurationIn_t configuration, const Transform3f &parentPosition, Transform3f &position) const =0
	Compute position of joint.
vector_t	neutralConfiguration () const
	Get neutral configuration of joint.
const size_type &	numberDof () const
	Return number of degrees of freedom.
const size_type &	configSize () const
	Return number of degrees of freedom.
const size_type &	rankInConfiguration () const
	Return rank of the joint in the configuration vector.
size_type	rankInVelocity () const
	Return rank of the joint in the velocity vector.
JointConfiguration *	configuration () const
void	robot (const DeviceWkPtr_t &device)
	Set robot owning the kinematic chain.
DeviceConstPtr_t	robot () const
	Access robot owning the object.
DevicePtr_t	robot ()
	Access robot owning the object.
virtual std::ostream &	display (std::ostream &os) const
	Display joint.
Construction and copy and destruction
	Joint (const Transform3f &initialPosition, size_type configSize, size_type numberDof)
	Constructor.
	Joint (const Joint &joint)
	Copy constructor.
virtual JointPtr_t	clone () const =0
	Return pointer to copy of this.
virtual	~Joint ()
Name
virtual void	name (const std::string &name)
	Set name.
virtual const std::string &	name () const
	Get name.
Kinematic chain
JointPtr_t	parentJoint () const
	Get a pointer to the parent joint (if any).
void	addChildJoint (JointPtr_t joint, bool computePositionInParent=true)
	Add child joint.
std::size_t	numberChildJoints () const
	Number of child joints.
JointPtr_t	childJoint (std::size_t rank) const
	Get child joint.
const Transform3f &	positionInParentFrame () const
	Get position of joint in parent frame.
void	positionInParentFrame (const Transform3f &p)
	Set position of joint in parent frame.
Bounds
Set whether given degree of freedom is bounded
void	isBounded (size_type rank, bool bounded)
bool	isBounded (size_type rank) const
	Get whether given degree of freedom is bounded.
value_type	lowerBound (size_type rank) const
	Get lower bound of given degree of freedom.
value_type	upperBound (size_type rank) const
	Get upper bound of given degree of freedom.
void	lowerBound (size_type rank, value_type lowerBound)
	Set lower bound of given degree of freedom.
void	upperBound (size_type rank, value_type upperBound)
	Set upper bound of given degree of freedom.
virtual value_type	upperBoundLinearVelocity () const =0
	Get upper bound on linear velocity of the joint frame.
virtual value_type	upperBoundAngularVelocity () const =0
	Get upper bound on angular velocity of the joint frame.
const value_type &	maximalDistanceToParent () const
	Maximal distance of joint origin to parent origin.
Jacobian
const JointJacobian_t &	jacobian () const
	Get const reference to Jacobian.
JointJacobian_t &	jacobian ()
	Get non const reference to Jacobian.
Body linked to the joint
Get linked body
BodyPtr_t	linkedBody () const
void	setLinkedBody (const BodyPtr_t &body)
	Set linked body.
Compatibility with urdf
const Transform3f &	linkInJointFrame () const
	Get urdf link position in joint frame.
void	linkInJointFrame (const Transform3f &transform)
	Set urdf link position in joint frame.
const std::string &	linkName () const
	Get link name.
void	linkName (const std::string &linkName)
	Set link name.
Protected Member Functions
virtual void	computeMaximalDistanceToParent ()=0
Protected Attributes
JointConfiguration *	configuration_
Transform3f	currentTransformation_
Transform3f	positionInParentFrame_
Transform3f	linkInJointFrame_
Transform3f	T3f_
value_type	mass_
	Mass of this and all descendants.
fcl::Vec3f	massCom_
	Mass time center of mass of this and all descendants.
value_type	maximalDistanceToParent_
vector_t	neutralConfiguration_
Friends
class	Device
class	ChildrenIterator
class	CenterOfMassComputation

Detailed Description

Robot joint.

A joint maps an input vector to a transformation of SE(3) from the parent frame to the joint frame.

The input vector is provided through the configuration vector of the robot the joint belongs to. The joint input vector is composed of the components of the robot configuration starting at Joint::rankInConfiguration.

The joint input vector represents a element of a Lie group, either

a vector space for JointTranslation, and bounded JointRotation,
the unit circle for non-bounded JointRotation joints,
an element of SO(3) for JointSO3, represented by a unit quaternion.

Operations specific to joints (uniform sampling of input space, straight interpolation, distance, ...) are performed by a JointConfiguration instance that has the same class hierarchy as Joint.

Constructor & Destructor Documentation

hpp::model::Joint::Joint	(	const Transform3f &	initialPosition,
		size_type	configSize,
		size_type	numberDof
	)

Constructor.

Parameters:

initialPosition	position of the joint before being inserted in a kinematic chain,
configSize	dimension of the configuration vector,
numberDof	dimension of the velocity vector.

hpp::model::Joint::Joint ( const Joint & joint )

Copy constructor.

Clone body and therefore inner and outer objects (see Body::clone).

virtual hpp::model::Joint::~Joint ( ) [virtual]

Member Function Documentation

void hpp::model::Joint::addChildJoint	(	JointPtr_t	joint,
		bool	computePositionInParent = `true`
	)

Add child joint.

Parameters:

joint	child joint added to this one,
computePositionInParent	whether to compute position of the child joint in this one's frame.

Note:: When building a kinematic chain, we usually build the joint in its initial position and compute the (constant) position of the joint in its parent when adding the joint in the kinematic chain. When copying a kinematic chain, we copy the position of the joint in its parent frame and therefore we do not update it when adding the joint in the kinematic chain.

JointPtr_t hpp::model::Joint::childJoint ( std::size_t rank ) const [inline]

Get child joint.

Referenced by hpp::model::ChildrenIterator::operator++().

virtual JointPtr_t hpp::model::Joint::clone ( ) const [pure virtual]

Return pointer to copy of this.

Clone body and therefore inner and outer objects (see Body::clone).

Implemented in hpp::model::JointTranslation< dimension >, hpp::model::jointRotation::Bounded, hpp::model::jointRotation::UnBounded, hpp::model::JointRotation, hpp::model::JointSO3, and hpp::model::JointAnchor.

virtual void hpp::model::Joint::computeMaximalDistanceToParent ( ) [protected, pure virtual]

Implemented in hpp::model::JointTranslation< dimension >, hpp::model::JointRotation, hpp::model::JointSO3, and hpp::model::JointAnchor.

virtual void hpp::model::Joint::computePosition	(	ConfigurationIn_t	configuration,
		const Transform3f &	parentPosition,
		Transform3f &	position
	)		const `[pure virtual]`

Compute position of joint.

Parameters:

configuration	the configuration of the robot,
parentPosition	position of parent joint,

Return values:

position position of this joint.

Implemented in hpp::model::JointTranslation< dimension >, hpp::model::jointRotation::Bounded, hpp::model::jointRotation::UnBounded, hpp::model::JointRotation, hpp::model::JointSO3, and hpp::model::JointAnchor.

const size_type& hpp::model::Joint::configSize ( ) const [inline]

Return number of degrees of freedom.

JointConfiguration* hpp::model::Joint::configuration ( ) const [inline]

const Transform3f& hpp::model::Joint::currentTransformation ( ) const

Joint transformation.

virtual std::ostream& hpp::model::Joint::display ( std::ostream & os ) const [virtual]

Display joint.

const Transform3f& hpp::model::Joint::initialPosition ( ) const

Joint initial position (when robot is in zero configuration)

void hpp::model::Joint::isBounded	(	size_type	rank,
		bool	bounded
	)

bool hpp::model::Joint::isBounded ( size_type rank ) const

Get whether given degree of freedom is bounded.

const JointJacobian_t& hpp::model::Joint::jacobian ( ) const [inline]

Get const reference to Jacobian.

JointJacobian_t& hpp::model::Joint::jacobian ( ) [inline]

Get non const reference to Jacobian.

BodyPtr_t hpp::model::Joint::linkedBody ( ) const

const Transform3f& hpp::model::Joint::linkInJointFrame ( ) const [inline]

Get urdf link position in joint frame.

When parsing urdf models, joint frames are reoriented in order to rotate about their x-axis. For some applications, it is necessary to be able to recover the position of the urdf link attached to the joint.

void hpp::model::Joint::linkInJointFrame ( const Transform3f & transform ) [inline]

Set urdf link position in joint frame.

const std::string& hpp::model::Joint::linkName ( ) const [inline]

Get link name.

void hpp::model::Joint::linkName ( const std::string & linkName ) [inline]

Set link name.

value_type hpp::model::Joint::lowerBound ( size_type rank ) const

Get lower bound of given degree of freedom.

void hpp::model::Joint::lowerBound	(	size_type	rank,
		value_type	lowerBound
	)

Set lower bound of given degree of freedom.

const value_type& hpp::model::Joint::maximalDistanceToParent ( ) const [inline]

Maximal distance of joint origin to parent origin.

virtual void hpp::model::Joint::name ( const std::string & name ) [inline, virtual]

Set name.

virtual const std::string& hpp::model::Joint::name ( ) const [inline, virtual]

Get name.

vector_t hpp::model::Joint::neutralConfiguration ( ) const [inline]

Get neutral configuration of joint.

Neutral configuration is

0 for translation joints,
(1,0,0,0) for SO3 joints,
(1,0) for unbounded rotation joint
0 for bounded rotation joint.

std::size_t hpp::model::Joint::numberChildJoints ( ) const [inline]

Number of child joints.

Referenced by hpp::model::ChildrenIterator::operator++().

const size_type& hpp::model::Joint::numberDof ( ) const [inline]

Return number of degrees of freedom.

JointPtr_t hpp::model::Joint::parentJoint ( ) const [inline]

Get a pointer to the parent joint (if any).

const Transform3f& hpp::model::Joint::positionInParentFrame ( ) const [inline]

Get position of joint in parent frame.

void hpp::model::Joint::positionInParentFrame ( const Transform3f & p ) [inline]

Set position of joint in parent frame.

const size_type& hpp::model::Joint::rankInConfiguration ( ) const [inline]

Return rank of the joint in the configuration vector.

size_type hpp::model::Joint::rankInVelocity ( ) const [inline]

Return rank of the joint in the velocity vector.

void hpp::model::Joint::robot ( const DeviceWkPtr_t & device ) [inline]

Set robot owning the kinematic chain.

DeviceConstPtr_t hpp::model::Joint::robot ( ) const [inline]

Access robot owning the object.

DevicePtr_t hpp::model::Joint::robot ( ) [inline]

Access robot owning the object.

void hpp::model::Joint::setLinkedBody ( const BodyPtr_t & body )

Set linked body.

value_type hpp::model::Joint::upperBound ( size_type rank ) const

Get upper bound of given degree of freedom.

void hpp::model::Joint::upperBound	(	size_type	rank,
		value_type	upperBound
	)

Set upper bound of given degree of freedom.

virtual value_type hpp::model::Joint::upperBoundAngularVelocity ( ) const [pure virtual]

Get upper bound on angular velocity of the joint frame.

Returns:

coefficient $\lambda$ such that

$\begin{equation*} \forall \mathbf{q}_{joint}\ \ \ \ \ \ \|\omega\| \leq \lambda \|\mathbf{\dot{q}}_{joint}\| \end{equation*}$

where

$\mathbf{q}_{joint}$ is any joint configuration,
$\mathbf{\dot{q}}_{joint}$ is the joint velocity, and
$\omega$ is the angular velocity of the joint frame.

Implemented in hpp::model::JointTranslation< dimension >, hpp::model::JointRotation, hpp::model::JointSO3, and hpp::model::JointAnchor.

virtual value_type hpp::model::Joint::upperBoundLinearVelocity ( ) const [pure virtual]

Get upper bound on linear velocity of the joint frame.

Returns:

coefficient $\lambda$ such that

$\begin{equation*} \forall \mathbf{q}_{joint}\ \ \ \ \ \ \|\mathbf {v}\| \leq \lambda \|\mathbf{\dot{q}}_{joint}\| \end{equation*}$

where

$\mathbf{q}_{joint}$ is any joint configuration,
$\mathbf{\dot{q}}_{joint}$ is the joint velocity, and
$\mathbf{v}$ is the linear velocity of the joint frame.

Implemented in hpp::model::JointTranslation< dimension >, hpp::model::JointRotation, hpp::model::JointSO3, and hpp::model::JointAnchor.

Friends And Related Function Documentation

friend class CenterOfMassComputation [friend]

friend class ChildrenIterator [friend]

friend class Device [friend]

Member Data Documentation

JointConfiguration* hpp::model::Joint::configuration_ [protected]

Transform3f hpp::model::Joint::currentTransformation_ [mutable, protected]

Transform3f hpp::model::Joint::linkInJointFrame_ [protected]

value_type hpp::model::Joint::mass_ [protected]

Mass of this and all descendants.

fcl::Vec3f hpp::model::Joint::massCom_ [protected]

Mass time center of mass of this and all descendants.

value_type hpp::model::Joint::maximalDistanceToParent_ [protected]

vector_t hpp::model::Joint::neutralConfiguration_ [protected]

Transform3f hpp::model::Joint::positionInParentFrame_ [protected]

Transform3f hpp::model::Joint::T3f_ [mutable, protected]

Public Member Functions

Protected Member Functions

Protected Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation