BulletBallJoint class models a ball joint in Bullet. More...

#include <BulletBallJoint.hh>

Public Types
enum	Attribute { FUDGE_FACTOR, SUSPENSION_ERP, SUSPENSION_CFM, STOP_ERP, STOP_CFM, ERP, CFM, FMAX, VEL, HI_STOP, LO_STOP }
	Joint attribute types. More...

enum	EntityType { BASE = 0x00000000, ENTITY = 0x00000001, MODEL = 0x00000002, LINK = 0x00000004, COLLISION = 0x00000008, LIGHT = 0x00000010, VISUAL = 0x00000020, JOINT = 0x00000040, BALL_JOINT = 0x00000080, HINGE2_JOINT = 0x00000100, HINGE_JOINT = 0x00000200, SLIDER_JOINT = 0x00000400, SCREW_JOINT = 0x00000800, UNIVERSAL_JOINT = 0x00001000, GEARBOX_JOINT = 0x00002000, FIXED_JOINT = 0x00004000, ACTOR = 0x00008000, SHAPE = 0x00010000, BOX_SHAPE = 0x00020000, CYLINDER_SHAPE = 0x00040000, HEIGHTMAP_SHAPE = 0x00080000, MAP_SHAPE = 0x00100000, MULTIRAY_SHAPE = 0x00200000, RAY_SHAPE = 0x00400000, PLANE_SHAPE = 0x00800000, SPHERE_SHAPE = 0x01000000, MESH_SHAPE = 0x02000000, POLYLINE_SHAPE = 0x04000000, SENSOR_COLLISION = 0x10000000 }
	Unique identifiers for all entity types. More...

Public Member Functions
	BulletBallJoint (btDynamicsWorld *_world, BasePtr _parent)
	Bullet Ball Joint Constructor. More...

virtual	~BulletBallJoint ()
	Destructor. More...

void	AddChild (BasePtr _child)
	Add a child to this entity. More...

void	AddType (EntityType _type)
	Add a type specifier. More...

virtual void	ApplyStiffnessDamping ()
	Callback to apply spring stiffness and viscous damping effects to joint. More...

bool	AreConnected (LinkPtr _one, LinkPtr _two) const
	Determines of the two bodies are connected by a joint. More...

virtual void	Attach (LinkPtr _parent, LinkPtr _child)
	Attach the two bodies with this joint. More...

virtual void	CacheForceTorque ()
	Cache Joint Force Torque Values if necessary for physics engine. More...

double	CheckAndTruncateForce (unsigned int _index, double _effort)
	check if the force against velocityLimit and effortLimit, truncate if necessary. More...

template<typename T >
event::ConnectionPtr	ConnectJointUpdate (T _subscriber)
	Connect a boost::slot the the joint update signal. More...

virtual void	Detach ()
	Detach this joint from all bodies. More...

void	DisconnectJointUpdate (event::ConnectionPtr &_conn)
	Disconnect a boost::slot the the joint update signal. More...

virtual void	FillMsg (msgs::Joint &_msg)
	Fill a joint message. More...

virtual void	Fini ()
	Finialize the object. More...

math::Vector3	GetAnchor (unsigned int _index) const
	Get the anchor point. More...

math::Pose	GetAnchorErrorPose () const
	Get pose offset between anchor pose on child and parent, expressed in the parent link frame. More...

math::Angle	GetAngle (unsigned int _index) const
	Get the angle of rotation of an axis(index) More...

virtual unsigned int	GetAngleCount () const

virtual math::Angle	GetAngleImpl (unsigned int _index) const
	Get the angle of an axis helper function. More...

virtual math::Vector3	GetAxis (unsigned int _index) const

math::Quaternion	GetAxisFrame (unsigned int _index) const
	Get orientation of reference frame for specified axis, relative to world frame. More...

math::Quaternion	GetAxisFrameOffset (unsigned int _index) const
	Get orientation of joint axis reference frame relative to joint frame. More...

BasePtr	GetByName (const std::string &_name)
	Get by name. More...

BasePtr	GetChild (unsigned int _i) const
	Get a child by index. More...

BasePtr	GetChild (const std::string &_name)
	Get a child by name. More...

LinkPtr	GetChild () const
	Get the child link. More...

unsigned int	GetChildCount () const
	Get the number of children. More...

double	GetDamping (unsigned int _index)
	Returns the current joint damping coefficient. More...

virtual double	GetEffortLimit (unsigned int _index)
	Get the effort limit on axis(index). More...

virtual double	GetForce (unsigned int _index)

virtual JointWrench	GetForceTorque (unsigned int _index)
	get internal force and torque values at a joint. More...

virtual math::Vector3	GetGlobalAxis (unsigned int _index) const
	Get the axis of rotation in global cooridnate frame. More...

virtual math::Angle	GetHighStop (unsigned int _index)
	Get the high stop of an axis(index). More...

uint32_t	GetId () const
	Return the ID of this entity. More...

double	GetInertiaRatio (const unsigned int _index) const
	Computes moment of inertia (MOI) across a specified joint axis. More...

double	GetInertiaRatio (const math::Vector3 &_axis) const
	Computes moment of inertia (MOI) across an arbitrary axis specified in the world frame. More...

math::Pose	GetInitialAnchorPose () const
	Get initial Anchor Pose specified by model <joint><pose>...</pose></joint> More...

LinkPtr	GetJointLink (unsigned int _index) const
	Get the body to which the joint is attached according the _index. More...

virtual math::Vector3	GetLinkForce (unsigned int _index) const
	Get the force the joint applies to the first body. More...

virtual math::Vector3	GetLinkTorque (unsigned int _index) const
	Get the torque the joint applies to the first body. More...

math::Vector3	GetLocalAxis (unsigned int _index) const
	Get the axis of rotation. More...

math::Angle	GetLowerLimit (unsigned int _index) const
	: get the joint upper limit (replaces GetLowStop and GetHighStop) More...

virtual math::Angle	GetLowStop (unsigned int _index)
	Get the low stop of an axis(index). More...

msgs::Joint::Type	GetMsgType () const
	Get the joint type as msgs::Joint::Type. More...

std::string	GetName () const
	Return the name of the entity. More...

virtual double	GetParam (const std::string &_key, unsigned int _index)
	Get a non-generic parameter for the joint. More...

LinkPtr	GetParent () const
	Get the parent link. More...

int	GetParentId () const
	Return the ID of the parent. More...

math::Pose	GetParentWorldPose () const
	Get anchor pose on parent link relative to world frame. More...

bool	GetSaveable () const
	Get whether the object should be "saved", when the user selects to save the world to xml. More...

std::string	GetScopedName (bool _prependWorldName=false) const
	Return the name of this entity with the model scope model1::...::modelN::entityName. More...

virtual const sdf::ElementPtr	GetSDF ()
	Get the SDF values for the object. More...

double	GetSpringReferencePosition (unsigned int _index) const
	Get joint spring reference position. More...

double	GetStiffness (unsigned int _index)
	Returns the current joint spring stiffness coefficient. More...

double	GetStopDissipation (unsigned int _index) const
	Get joint stop dissipation. More...

double	GetStopStiffness (unsigned int _index) const
	Get joint stop stiffness. More...

unsigned int	GetType () const
	Get the full type definition. More...

math::Angle	GetUpperLimit (unsigned int _index) const
	: get the joint lower limit (replacee GetLowStop and GetHighStop) More...

virtual double	GetVelocity (unsigned int _index) const
	Get the rotation rate of an axis(index) More...

virtual double	GetVelocityLimit (unsigned int _index)
	Get the velocity limit on axis(index). More...

const WorldPtr &	GetWorld () const
	Get the World this object is in. More...

double	GetWorldEnergyPotentialSpring (unsigned int _index) const
	Returns this joint's spring potential energy, based on the reference position of the spring. More...

math::Pose	GetWorldPose () const
	Get pose of joint frame relative to world frame. More...

bool	HasType (const EntityType &_t) const
	Returns true if this object's type definition has the given type. More...

virtual void	Init ()
	Initialize joint. More...

bool	IsSelected () const
	True if the entity is selected by the user. More...

virtual void	Load (sdf::ElementPtr _sdf)
	Load a BulletJoint. More...

void	Load (LinkPtr _parent, LinkPtr _child, const math::Pose &_pose)
	Set pose, parent and child links of a physics::Joint. More...

bool	operator== (const Base &_ent) const
	Returns true if the entities are the same. More...

void	Print (const std::string &_prefix)
	Print this object to screen via gzmsg. More...

virtual void	RemoveChild (unsigned int _id)
	Remove a child from this entity. More...

void	RemoveChild (const std::string &_name)
	Remove a child by name. More...

void	RemoveChildren ()
	Remove all children. More...

virtual void	Reset ()
	Reset the joint. More...

virtual void	Reset (Base::EntityType _resetType)
	Calls recursive Reset on one of the Base::EntityType's. More...

virtual void	SetAnchor (unsigned int _index, const gazebo::math::Vector3 &_anchor)
	Set the anchor point. More...

virtual void	SetAxis (unsigned int _index, const math::Vector3 &_axis)
	Set the axis of rotation where axis is specified in local joint frame. More...

virtual void	SetDamping (unsigned int _index, double _damping)
	Set the joint damping. More...

virtual void	SetEffortLimit (unsigned int _index, double _effort)
	Set the effort limit on a joint axis. More...

virtual void	SetForce (unsigned int _index, double _force)
	Set the force applied to this physics::Joint. More...

virtual bool	SetHighStop (unsigned int _index, const math::Angle &_angle)
	Set the high stop of an axis(index). More...

void	SetLowerLimit (unsigned int _index, math::Angle _limit)
	: set the joint upper limit (replaces SetLowStop and SetHighStop) More...

virtual bool	SetLowStop (unsigned int _index, const math::Angle &_angle)
	Set the low stop of an axis(index). More...

void	SetModel (ModelPtr _model)
	Set the model this joint belongs too. More...

virtual void	SetName (const std::string &_name)
	Set the name of the entity. More...

virtual bool	SetParam (const std::string &_key, unsigned int _index, const boost::any &_value)
	Set a non-generic parameter for the joint. More...

void	SetParent (BasePtr _parent)
	Set the parent. More...

virtual bool	SetPosition (unsigned int _index, double _position)
	The child links of this joint are updated based on desired position. More...

virtual void	SetProvideFeedback (bool _enable)
	Set whether the joint should generate feedback. More...

void	SetSaveable (bool _v)
	Set whether the object should be "saved", when the user selects to save the world to xml. More...

virtual bool	SetSelected (bool _show)
	Set whether this entity has been selected by the user through the gui. More...

void	SetState (const JointState &_state)
	Set the joint state. More...

virtual void	SetStiffness (unsigned int _index, const double _stiffness)
	Set the joint spring stiffness. More...

virtual void	SetStiffnessDamping (unsigned int _index, double _stiffness, double _damping, double _reference=0)
	Set the joint spring stiffness. More...

void	SetStopDissipation (unsigned int _index, double _dissipation)
	Set joint stop dissipation. More...

void	SetStopStiffness (unsigned int _index, double _stiffness)
	Set joint stop stiffness. More...

void	SetUpperLimit (unsigned int _index, math::Angle _limit)
	: set the joint lower limit (replacee GetLowStop and GetHighStop) More...

virtual void	SetVelocity (unsigned int _index, double _angle)
	Set the velocity of an axis(index). More...

virtual void	SetVelocityLimit (unsigned int _index, double _velocity)
	Set the velocity limit on a joint axis. More...

void	SetWorld (const WorldPtr &_newWorld)
	Set the world this object belongs to. More...

std::string	TypeStr () const
	Get the string name for the entity type. More...

void	Update ()
	Update the joint. More...

virtual void	UpdateParameters (sdf::ElementPtr _sdf)
	Update the parameters using new sdf values. More...

common::URI	URI () const
	Return the common::URI of this entity. More...

Protected Member Functions
math::Pose	ComputeChildLinkPose (unsigned int _index, double _position)
	internal function to help us compute child link pose if a joint position change is applied. More...

void	ComputeScopedName ()
	Compute the scoped name of this object based on its parents. More...

bool	FindAllConnectedLinks (const LinkPtr &_originalParentLink, Link_V &_connectedLinks)
	internal helper to find all links connected to the child link branching out from the children of the child link and any parent of the child link other than the parent link through this joint. More...

virtual void	SetForceImpl (unsigned int _index, double _torque)
	Set the force applied to this physics::Joint. More...

bool	SetPositionMaximal (unsigned int _index, double _position)
	Helper function for maximal coordinate solver SetPosition. More...

void	SetupJointFeedback ()
	: Setup joint feedback datatructure. More...

bool	SetVelocityMaximal (unsigned int _index, double _velocity)
	Helper function for maximal coordinate solver SetVelocity. More...

Protected Attributes
LinkPtr	anchorLink
	Anchor link. More...

math::Vector3	anchorPos
	Anchor pose. More...

math::Pose	anchorPose
	Anchor pose specified in SDF <joint><pose> tag. More...

gazebo::event::ConnectionPtr	applyDamping
	apply damping for adding viscous damping forces on updates More...

bool	axisParentModelFrame [2]
	Flags that are set to true if an axis value is expressed in the parent model frame. More...

btDynamicsWorld *	bulletWorld
	Pointer to Bullet's btDynamicsWorld. More...

LinkPtr	childLink
	The first link this joint connects to. More...

Base_V	children
	Children of this entity. More...

btTypedConstraint *	constraint
	Pointer to a contraint object in Bullet. More...

double	dissipationCoefficient [2]
	joint viscous damping coefficient More...

double	effortLimit [2]
	Store Joint effort limit as specified in SDF. More...

math::Angle	lowerLimit [2]
	Store Joint position lower limit as specified in SDF. More...

ModelPtr	model
	Pointer to the parent model. More...

BasePtr	parent
	Parent of this entity. More...

math::Pose	parentAnchorPose
	Anchor pose relative to parent link frame. More...

LinkPtr	parentLink
	The second link this joint connects to. More...

bool	provideFeedback
	Provide Feedback data for contact forces. More...

sdf::ElementPtr	sdf
	The SDF values for this object. More...

double	springReferencePosition [2]
	joint spring reference (zero load) position More...

double	stiffnessCoefficient [2]
	joint stiffnessCoefficient More...

math::Angle	upperLimit [2]
	Store Joint position upper limit as specified in SDF. More...

double	velocityLimit [2]
	Store Joint velocity limit as specified in SDF. More...

WorldPtr	world
	Pointer to the world. More...

JointWrench	wrench
	Cache Joint force torque values in case physics engine clears them at the end of update step. More...

Detailed Description

BulletBallJoint class models a ball joint in Bullet.

Member Enumeration Documentation

enum Attribute

inherited

Joint attribute types.

Enumerator
FUDGE_FACTOR	Fudge factor.
SUSPENSION_ERP	Suspension error reduction parameter.
SUSPENSION_CFM	Suspension constraint force mixing.
STOP_ERP	Stop limit error reduction parameter.
STOP_CFM	Stop limit constraint force mixing.
ERP	Error reduction parameter.
CFM	Constraint force mixing.
FMAX	Maximum force.
VEL	Velocity.
HI_STOP	High stop angle.
LO_STOP	Low stop angle.

enum EntityType

inherited

Unique identifiers for all entity types.

Enumerator
BASE	Base type.
ENTITY	Entity type.
MODEL	Model type.
LINK	Link type.
COLLISION	Collision type.
LIGHT	Light type.
VISUAL	Visual type.
JOINT	Joint type.
BALL_JOINT	BallJoint type.
HINGE2_JOINT	Hing2Joint type.
HINGE_JOINT	HingeJoint type.
SLIDER_JOINT	SliderJoint type.
SCREW_JOINT	ScrewJoint type.
UNIVERSAL_JOINT	UniversalJoint type.
GEARBOX_JOINT	GearboxJoint type.
FIXED_JOINT	FixedJoint type.
ACTOR	Actor type.
SHAPE	Shape type.
BOX_SHAPE	BoxShape type.
CYLINDER_SHAPE	CylinderShape type.
HEIGHTMAP_SHAPE	HeightmapShape type.
MAP_SHAPE	MapShape type.
MULTIRAY_SHAPE	MultiRayShape type.
RAY_SHAPE	RayShape type.
PLANE_SHAPE	PlaneShape type.
SPHERE_SHAPE	SphereShape type.
MESH_SHAPE	MeshShape type.
POLYLINE_SHAPE	PolylineShape type.
SENSOR_COLLISION	Indicates a collision shape used for sensing.

Constructor & Destructor Documentation

BulletBallJoint	(	btDynamicsWorld *	_world,
		BasePtr	_parent
	)

Bullet Ball Joint Constructor.

virtual ~BulletBallJoint ( )

virtual

Destructor.

Member Function Documentation

void AddChild ( BasePtr _child )

inherited

Add a child to this entity.

Parameters

[in] _child Child entity.

void AddType ( EntityType _type )

inherited

Add a type specifier.

Parameters

[in] _type New type to append to this objects type definition.

virtual void ApplyStiffnessDamping ( )

virtualinherited

Callback to apply spring stiffness and viscous damping effects to joint.

: rename to ApplySpringStiffnessDamping()

Reimplemented from Joint.

bool AreConnected	(	LinkPtr	_one,
		LinkPtr	_two
	)		const

virtualinherited

Determines of the two bodies are connected by a joint.

Implements Joint.

virtual void Attach	(	LinkPtr	_parent,
		LinkPtr	_child
	)

virtualinherited

Attach the two bodies with this joint.

Parameters

[in]	_parent	Parent link.
[in]	_child	Child link.

Reimplemented in ODEJoint, ODEFixedJoint, and DARTJoint.

virtual void CacheForceTorque ( )

virtualinherited

Cache Joint Force Torque Values if necessary for physics engine.

Reimplemented from Joint.

double CheckAndTruncateForce	(	unsigned int	_index,
		double	_effort
	)

inherited

check if the force against velocityLimit and effortLimit, truncate if necessary.

Parameters

[in]	_index	Index of the axis.
[in]	_effort	Force value.

Returns: truncated effort

math::Pose ComputeChildLinkPose	(	unsigned int	_index,
		double	_position
	)

protectedinherited

internal function to help us compute child link pose if a joint position change is applied.

Parameters

[in]	_index	axis index
[in]	_position	new joint position

Returns: new child link pose at new joint position.

void ComputeScopedName ( )

protectedinherited

Compute the scoped name of this object based on its parents.

See Also: Base::GetScopedName

event::ConnectionPtr ConnectJointUpdate ( T _subscriber )

inlineinherited

Connect a boost::slot the the joint update signal.

Parameters

[in] _subscriber Callback for the connection.

Returns: Connection pointer, which must be kept in scope.

References EventT< T >::Connect().

virtual void Detach ( )

virtualinherited

Detach this joint from all bodies.

Reimplemented from Joint.

void DisconnectJointUpdate ( event::ConnectionPtr & _conn )

inlineinherited

Disconnect a boost::slot the the joint update signal.

Parameters

[in] _conn Connection to disconnect.

References EventT< T >::Disconnect().

virtual void FillMsg ( msgs::Joint & _msg )

virtualinherited

Fill a joint message.

Parameters

[out] _msg Message to fill with this joint's properties.

Reimplemented in GearboxJoint< ODEJoint >, ScrewJoint< ODEJoint >, ScrewJoint< DARTJoint >, ScrewJoint< SimbodyJoint >, and ScrewJoint< BulletJoint >.

Referenced by ScrewJoint< BulletJoint >::FillMsg(), and GearboxJoint< ODEJoint >::FillMsg().

bool FindAllConnectedLinks	(	const LinkPtr &	_originalParentLink,
		Link_V &	_connectedLinks
	)

protectedinherited

internal helper to find all links connected to the child link branching out from the children of the child link and any parent of the child link other than the parent link through this joint.

Parameters

[in]	_originalParentLink	parent link of this joint, this is used to check for loops connecting back to the parent link.
	in/out]	_connectedLinks list of aggregated links that contains all links connected to the child link of this joint. Empty if a loop is found that connects back to the parent link.

Returns: true if successful, false if a loop is found that connects back to the parent link.

virtual void Fini ( )

virtualinherited

Finialize the object.

Reimplemented from Joint.

math::Vector3 GetAnchor ( unsigned int _index ) const

virtual

Get the anchor point.

Reimplemented from BulletJoint.

math::Pose GetAnchorErrorPose ( ) const

inherited

Get pose offset between anchor pose on child and parent, expressed in the parent link frame.

This can be used to compute the bilateral constraint error.

Returns: Pose offset between anchor pose on child and parent, in parent link frame.

math::Angle GetAngle ( unsigned int _index ) const

inherited

Get the angle of rotation of an axis(index)

Parameters

[in] _index Index of the axis.

Returns: Angle of the axis.

virtual unsigned int GetAngleCount ( ) const

inlinevirtualinherited

Implements Joint.

virtual math::Angle GetAngleImpl ( unsigned int _index ) const

virtual

Get the angle of an axis helper function.

Parameters

[in] _index Index of the axis.

Returns: Angle of the axis.

Implements Joint.

virtual math::Vector3 GetAxis ( unsigned int _index ) const

virtual

math::Quaternion GetAxisFrame ( unsigned int _index ) const

inherited

Get orientation of reference frame for specified axis, relative to world frame.

The value of axisParentModelFrame is used to determine the appropriate frame.

Parameters

[in] _index joint axis index.

Returns: Orientation of axis frame relative to world frame.

math::Quaternion GetAxisFrameOffset ( unsigned int _index ) const

inherited

Get orientation of joint axis reference frame relative to joint frame.

This should always return identity unless flag use_parent_model_frame is true in sdf 1.5 or using sdf 1.4-, i.e. bug described in issue #494 is present. In addition, if use_parent_model_frame is true, and the parent link of the joint is world, the axis is defined in the world frame. The value of axisParentModelFrame is used to determine the appropriate frame internally.

Parameters

[in] _index joint axis index.

Returns: Orientation of axis frame relative to joint frame. If supplied _index is out of range, or use_parent_model_frame is not true, this function returns identity rotation quaternion.

BasePtr GetByName ( const std::string & _name )

inherited

Get by name.

Parameters

[in] _name Get a child (or self) object by name

Returns: A pointer to the object, NULL if not found

BasePtr GetChild ( unsigned int _i ) const

inherited

Get a child by index.

Parameters

[in] _i Index of the child to retreive.

Returns: A pointer to the object, NULL if the index is invalid.

BasePtr GetChild ( const std::string & _name )

inherited

Get a child by name.

Parameters

[in] _name Name of the child.

Returns: A pointer to the object, NULL if not found

LinkPtr GetChild ( ) const

inherited

Get the child link.

Returns: Pointer to the child link.

unsigned int GetChildCount ( ) const

inherited

Get the number of children.

Returns: The number of children.

double GetDamping ( unsigned int _index )

inherited

Returns the current joint damping coefficient.

Parameters

[in] _index Index of the axis to get, currently ignored, to be implemented.

Returns: Joint viscous damping coefficient for this joint.

virtual double GetEffortLimit ( unsigned int _index )

virtualinherited

Get the effort limit on axis(index).

Parameters

[in] _index Index of axis, where 0=first axis and 1=second axis

Returns: Effort limit specified in SDF

virtual double GetForce ( unsigned int _index )

virtualinherited

Todo:

: not yet implemented. Get external forces applied at this Joint. Note that the unit of force should be consistent with the rest of the simulation scales.

Parameters

[in] _index Index of the axis.

Returns: The force applied to an axis.

Reimplemented from Joint.

virtual JointWrench GetForceTorque ( unsigned int _index )

virtualinherited

get internal force and torque values at a joint.

The force and torque values are returned in a JointWrench data structure. Where JointWrench.body1Force contains the force applied by the parent Link on the Joint specified in the parent Link frame, and JointWrench.body2Force contains the force applied by the child Link on the Joint specified in the child Link frame. Note that this sign convention is opposite of the reaction forces of the Joint on the Links.

FIXME TODO: change name of this function to something like: GetNegatedForceTorqueInLinkFrame and make GetForceTorque call return non-negated reaction forces in perspective Link frames.

Note that for ODE you must set <provide_feedback>true<provide_feedback> in the joint sdf to use this.

Parameters

[in] _index Not used right now

Returns: The force and torque at the joint, see above for details on conventions.

Implements Joint.

virtual math::Vector3 GetGlobalAxis ( unsigned int _index ) const

virtual

Get the axis of rotation in global cooridnate frame.

Parameters

[in] _index Index of the axis to get.

Returns: Axis value for the provided index.

Implements Joint.

virtual math::Angle GetHighStop ( unsigned int _index )

virtual

Get the high stop of an axis(index).

This function is replaced by GetUpperLimit(unsigned int). If you are interested in getting the value of dParamHiStop*, use GetAttribute(hi_stop, _index)

Parameters

[in] _index Index of the axis.

Returns: Angle of the high stop value.

Reimplemented from BulletJoint.

uint32_t GetId ( ) const

inherited

Return the ID of this entity.

This id is unique.

Returns: Integer ID.

double GetInertiaRatio ( const unsigned int _index ) const

inherited

Computes moment of inertia (MOI) across a specified joint axis.

The ratio is given in the form of MOI_chidl / MOI_parent. If MOI_parent is zero, this funciton will return 0. The inertia ratio for each joint axis indicates the sensitivity of the joint to actuation torques.

Parameters

[in] _index axis number about which MOI ratio is computed.

Returns: ratio of child MOI to parent MOI.

double GetInertiaRatio ( const math::Vector3 & _axis ) const

inherited

Computes moment of inertia (MOI) across an arbitrary axis specified in the world frame.

The ratio is given in the form of MOI_chidl / MOI_parent. If MOI_parent is zero, this funciton will return 0. The moment of inertia ratio along constrained directions of a joint has an impact on the performance of Projected Gauss Seidel (PGS) iterative LCP methods.

Parameters

[in] _axis axis in world frame for which MOI ratio is computed.

Returns: ratio of child MOI to parent MOI.

math::Pose GetInitialAnchorPose ( ) const

inherited

Get initial Anchor Pose specified by model <joint><pose>...</pose></joint>

Returns: Joint::anchorPose, initial joint anchor pose.

LinkPtr GetJointLink ( unsigned int _index ) const

virtualinherited

Get the body to which the joint is attached according the _index.

Implements Joint.

virtual math::Vector3 GetLinkForce ( unsigned int _index ) const

virtualinherited

Get the force the joint applies to the first body.

Parameters

index The index of the body(0 or 1)

Implements Joint.

virtual math::Vector3 GetLinkTorque ( unsigned int _index ) const

virtualinherited

Get the torque the joint applies to the first body.

Parameters

index The index of the body(0 or 1)

Implements Joint.

math::Vector3 GetLocalAxis ( unsigned int _index ) const

inherited

Get the axis of rotation.

Parameters

[in] _index Index of the axis to get.

Returns: Axis value for the provided index.

math::Angle GetLowerLimit ( unsigned int _index ) const

inherited

: get the joint upper limit (replaces GetLowStop and GetHighStop)

Parameters

[in] _index Index of the axis.

Returns: Lower limit of the axis.

virtual math::Angle GetLowStop ( unsigned int _index )

virtual

Get the low stop of an axis(index).

This function is replaced by GetLowerLimit(unsigned int). If you are interested in getting the value of dParamHiStop*, use GetAttribute(hi_stop, _index)

Parameters

[in] _index Index of the axis.

Returns: Angle of the low stop value.

Reimplemented from BulletJoint.

msgs::Joint::Type GetMsgType ( ) const

inherited

Get the joint type as msgs::Joint::Type.

Returns: Joint type.

std::string GetName ( ) const

inherited

Return the name of the entity.

Returns: Name of the entity.

virtual double GetParam	(	const std::string &	_key,
		unsigned int	_index
	)

virtualinherited

Get a non-generic parameter for the joint.

See Also: SetParam(const std::string &, unsigned int, const boost::any)

Parameters

[in]	_key	String key.
[in]	_index	Index of the axis.

Reimplemented from Joint.

Reimplemented in BulletScrewJoint, BulletSliderJoint, BulletHingeJoint, and BulletUniversalJoint.

LinkPtr GetParent ( ) const

inherited

Get the parent link.

Returns: Pointer to the parent link.

int GetParentId ( ) const

inherited

Return the ID of the parent.

Returns: Integer ID.

math::Pose GetParentWorldPose ( ) const

inherited

Get anchor pose on parent link relative to world frame.

When there is zero joint error, this should match the value returned by Joint::GetWorldPose() for the constrained degrees of freedom.

Returns: Anchor pose on parent link in world frame.

bool GetSaveable ( ) const

inherited

Get whether the object should be "saved", when the user selects to save the world to xml.

Returns: True if the object is saveable.

std::string GetScopedName ( bool _prependWorldName = false ) const

inherited

Return the name of this entity with the model scope model1::...::modelN::entityName.

Parameters

[in] _prependWorldName True to prended the returned string with the world name. The result will be world::model1::...::modelN::entityName.

Returns: The scoped name.

virtual const sdf::ElementPtr GetSDF ( )

virtualinherited

Get the SDF values for the object.

Returns: The SDF values for the object.

Reimplemented in Actor, and Model.

double GetSpringReferencePosition ( unsigned int _index ) const

inherited

Get joint spring reference position.

Parameters

[in] _index Index of the axis to get.

Returns: Joint spring reference position (in radians for angular joints).

double GetStiffness ( unsigned int _index )

inherited

Returns the current joint spring stiffness coefficient.

Parameters

[in] _index Index of the axis to get, currently ignored, to be implemented.

Returns: Joint spring stiffness coefficient for this joint. : rename to GetSpringStiffness()

double GetStopDissipation ( unsigned int _index ) const

inherited

Get joint stop dissipation.

Parameters

[in] _index joint axis index.

Returns: joint stop dissipation coefficient.

double GetStopStiffness ( unsigned int _index ) const

inherited

Get joint stop stiffness.

Parameters

[in] _index joint axis index.

Returns: joint stop stiffness coefficient.

unsigned int GetType ( ) const

inherited

Get the full type definition.

Returns: The full type definition.

math::Angle GetUpperLimit ( unsigned int _index ) const

inherited

: get the joint lower limit (replacee GetLowStop and GetHighStop)

Parameters

[in] _index Index of the axis.

Returns: Upper limit of the axis.

virtual double GetVelocity ( unsigned int _index ) const

virtual

Get the rotation rate of an axis(index)

Parameters

[in] _index Index of the axis.

Returns: The rotaional velocity of the joint axis.

Implements Joint.

virtual double GetVelocityLimit ( unsigned int _index )

virtualinherited

Get the velocity limit on axis(index).

Parameters

[in] _index Index of axis, where 0=first axis and 1=second axis

Returns: Velocity limit specified in SDF

const WorldPtr& GetWorld ( ) const

inherited

Get the World this object is in.

Returns: The World this object is part of.

double GetWorldEnergyPotentialSpring ( unsigned int _index ) const

inherited

Returns this joint's spring potential energy, based on the reference position of the spring.

If using metric system, the unit of energy will be Joules.

Returns: this joint's spring potential energy,

math::Pose GetWorldPose ( ) const

inherited

Get pose of joint frame relative to world frame.

Note that the joint frame is defined with a fixed offset from the child link frame.

Returns: Pose of joint frame relative to world frame.

bool HasType ( const EntityType & _t ) const

inherited

Returns true if this object's type definition has the given type.

Parameters

[in] _t Type to check.

Returns: True if this object's type definition has the.

virtual void Init ( )

virtual

Initialize joint.

Reimplemented from BallJoint< BulletJoint >.

bool IsSelected ( ) const

inherited

True if the entity is selected by the user.

Returns: True if the entity is selected.

virtual void Load ( sdf::ElementPtr _sdf )

virtual

Load a BulletJoint.

Reimplemented from BulletJoint.

void Load	(	LinkPtr	_parent,
		LinkPtr	_child,
		const math::Pose &	_pose
	)

inherited

Set pose, parent and child links of a physics::Joint.

Parameters

[in]	_parent	Parent link.
[in]	_child	Child link.
[in]	_pose	Pose containing Joint Anchor offset from child link.

bool operator== ( const Base & _ent ) const

inherited

Returns true if the entities are the same.

Checks only the name.

Parameters

[in] _ent Base object to compare with.

Returns: True if the entities are the same.

void Print ( const std::string & _prefix )

inherited

Print this object to screen via gzmsg.

Parameters

[in] _prefix Usually a set of spaces.

virtual void RemoveChild ( unsigned int _id )

virtualinherited

Remove a child from this entity.

Parameters

[in] _id ID of the child to remove.

void RemoveChild ( const std::string & _name )

inherited

Remove a child by name.

Parameters

[in] _name Name of the child.

void RemoveChildren ( )

inherited

Remove all children.

virtual void Reset ( )

virtualinherited

Reset the joint.

Reimplemented from Joint.

virtual void Reset ( Base::EntityType _resetType )

virtualinherited

Calls recursive Reset on one of the Base::EntityType's.

Parameters

[in] _resetType The type of reset operation

virtual void SetAnchor	(	unsigned int	_index,
		const gazebo::math::Vector3 &	_anchor
	)

virtualinherited

Set the anchor point.

Implements Joint.

Reimplemented in BulletScrewJoint.

virtual void SetAxis	(	unsigned int	_index,
		const math::Vector3 &	_axis
	)

virtual

Set the axis of rotation where axis is specified in local joint frame.

Parameters

[in]	_index	Index of the axis to set.
[in]	_axis	Vector in local joint frame of axis direction (must have length greater than zero).

Implements Joint.

virtual void SetDamping	(	unsigned int	_index,
		double	_damping
	)

virtualinherited

Set the joint damping.

Parameters

[in]	_index	Index of the axis to set, currently ignored, to be implemented.
[in]	_damping	Damping value for the axis.

Implements Joint.

Reimplemented in BulletSliderJoint.

virtual void SetEffortLimit	(	unsigned int	_index,
		double	_effort
	)

virtualinherited

Set the effort limit on a joint axis.

Parameters

[in]	_index	Index of the axis to set.
[in]	_effort	Effort limit for the axis.

virtual void SetForce	(	unsigned int	_index,
		double	_effort
	)

virtualinherited

Set the force applied to this physics::Joint.

Note that the unit of force should be consistent with the rest of the simulation scales. Force is additive (multiple calls to SetForce to the same joint in the same time step will accumulate forces on that Joint). Forces are truncated by effortLimit before applied.

Parameters

[in]	_index	Index of the axis.
[in]	_effort	Force value.

Implements Joint.

virtual void SetForceImpl	(	unsigned int	_index,
		double	_force
	)

protectedvirtual

Set the force applied to this physics::Joint.

Note that the unit of force should be consistent with the rest of the simulation scales. Force is additive (multiple calls to SetForceImpl to the same joint in the same time step will accumulate forces on that Joint).

Parameters

[in]	_index	Index of the axis.
[in]	_force	Force value. internal force, e.g. damping forces. This way, Joint::appliedForce keep track of external forces only.

Implements BulletJoint.

virtual bool SetHighStop	(	unsigned int	_index,
		const math::Angle &	_angle
	)

virtual

Set the high stop of an axis(index).

Parameters

[in]	_index	Index of the axis.
[in]	_angle	High stop angle.

Reimplemented from Joint.

void SetLowerLimit	(	unsigned int	_index,
		math::Angle	_limit
	)

inherited

: set the joint upper limit (replaces SetLowStop and SetHighStop)

Parameters

[in]	_index	Index of the axis.
[in]	_limit	Lower limit of the axis.

virtual bool SetLowStop	(	unsigned int	_index,
		const math::Angle &	_angle
	)

virtual

Set the low stop of an axis(index).

Parameters

[in]	_index	Index of the axis.
[in]	_angle	Low stop angle.

Reimplemented from Joint.

void SetModel ( ModelPtr _model )

inherited

Set the model this joint belongs too.

Parameters

[in] _model Pointer to a model.

virtual void SetName ( const std::string & _name )

virtualinherited

Set the name of the entity.

Parameters

[in] _name New name.

Reimplemented in Entity.

virtual bool SetParam	(	const std::string &	_key,
		unsigned int	_index,
		const boost::any &	_value
	)

virtualinherited

Set a non-generic parameter for the joint.

replaces SetAttribute(Attribute, int, double) List of parameters: "friction" Axis Coulomb joint friction coefficient. "hi_stop" Axis upper limit. "lo_stop" Axis lower limit.

Parameters

[in]	_key	String key.
[in]	_index	Index of the axis.
[in]	_value	Value of the attribute.

Implements Joint.

Reimplemented in BulletSliderJoint, BulletHingeJoint, and BulletUniversalJoint.

void SetParent ( BasePtr _parent )

inherited

Set the parent.

Parameters

[in] _parent Parent object.

virtual bool SetPosition	(	unsigned int	_index,
		double	_position
	)

virtualinherited

The child links of this joint are updated based on desired position.

And all the links connected to the child link of this joint except through the parent link of this joint moves with the child link.

Parameters

[in]	_index	Index of the joint axis (degree of freedom).
[in]	_position	Position to set the joint to. unspecified, pure kinematic teleportation.

Returns: returns true if operation succeeds, false if it fails.

Reimplemented from Joint.

bool SetPositionMaximal	(	unsigned int	_index,
		double	_position
	)

protectedinherited

Helper function for maximal coordinate solver SetPosition.

The child links of this joint are updated based on position change. And all the links connected to the child link of this joint except through the parent link of this joint moves with the child link.

Parameters

[in]	_index	Index of the joint axis (degree of freedom).
[in]	_position	Position to set the joint to.

Returns: returns true if operation succeeds, false if it fails.

virtual void SetProvideFeedback ( bool _enable )

virtualinherited

Set whether the joint should generate feedback.

Parameters

[in] _enable True to enable joint feedback.

Reimplemented from Joint.

void SetSaveable ( bool _v )

inherited

Set whether the object should be "saved", when the user selects to save the world to xml.

Parameters

[in] _v Set to True if the object should be saved.

virtual bool SetSelected ( bool _show )

virtualinherited

Set whether this entity has been selected by the user through the gui.

Parameters

[in] _show True to set this entity as selected.

Reimplemented in Link.

void SetState ( const JointState & _state )

inherited

Set the joint state.

Parameters

[in] _state Joint state

virtual void SetStiffness	(	unsigned int	_index,
		const double	_stiffness
	)

virtualinherited

Set the joint spring stiffness.

Parameters

[in]	_index	Index of the axis to set, currently ignored, to be implemented.
[in]	_stiffness	Spring stiffness value for the axis. : rename to SetSpringStiffness()

Implements Joint.

virtual void SetStiffnessDamping	(	unsigned int	_index,
		double	_stiffness,
		double	_damping,
		double	_reference = `0`
	)

virtualinherited

Set the joint spring stiffness.

Parameters

[in]	_index	Index of the axis to set, currently ignored, to be implemented.
[in]	_stiffness	Stiffness value for the axis.
[in]	_reference	Spring zero load reference position. : rename to SetSpringStiffnessDamping()

Implements Joint.

void SetStopDissipation	(	unsigned int	_index,
		double	_dissipation
	)

inherited

Set joint stop dissipation.

Parameters

[in]	_index	joint axis index.
[in]	_dissipation	joint stop dissipation coefficient.

void SetStopStiffness	(	unsigned int	_index,
		double	_stiffness
	)

inherited

Set joint stop stiffness.

Parameters

[in]	_index	joint axis index.
[in]	_stiffness	joint stop stiffness coefficient.

void SetupJointFeedback ( )

protectedinherited

: Setup joint feedback datatructure.

This is called after Joint::constraint is setup in Init.

void SetUpperLimit	(	unsigned int	_index,
		math::Angle	_limit
	)

inherited

: set the joint lower limit (replacee GetLowStop and GetHighStop)

Parameters

[in]	_index	Index of the axis.
[in]	_limit	Upper limit of the axis.

virtual void SetVelocity	(	unsigned int	_index,
		double	_vel
	)

virtual

Set the velocity of an axis(index).

In ODE and Bullet, the SetVelocityMaximal function is used to set the velocity of the child link relative to the parent. In Simbody and DART, this function updates the velocity state, which has a recursive effect on the rest of the chain.

Parameters

[in]	_index	Index of the axis.
[in]	_vel	Velocity.

Implements Joint.

virtual void SetVelocityLimit	(	unsigned int	_index,
		double	_velocity
	)

virtualinherited

Set the velocity limit on a joint axis.

Parameters

[in]	_index	Index of the axis to set.
[in]	_velocity	Velocity limit for the axis.

bool SetVelocityMaximal	(	unsigned int	_index,
		double	_velocity
	)

protectedinherited

Helper function for maximal coordinate solver SetVelocity.

The velocity of the child link of this joint is updated relative to the current parent velocity. It currently does not act recursively.

Parameters

[in]	_index	Index of the joint axis (degree of freedom).
[in]	_velocity	Velocity to set at this joint.

Returns: returns true if operation succeeds, false if it fails.

void SetWorld ( const WorldPtr & _newWorld )

inherited

Set the world this object belongs to.

This will also set the world for all children.

Parameters

[in] _newWorld The new World this object is part of.

std::string TypeStr ( ) const

inherited

Get the string name for the entity type.

Returns: The string name for this entity.

void Update ( )

virtualinherited

Update the joint.

Reimplemented from Base.

virtual void UpdateParameters ( sdf::ElementPtr _sdf )

virtualinherited

Update the parameters using new sdf values.

Parameters

[in] _sdf SDF values to update from.

Reimplemented from Base.

common::URI URI ( ) const

inherited

Return the common::URI of this entity.

The URI includes the world where the entity is contained and all the hierarchy of sub-entities that can compose this entity. E.g.: A link entity contains the name of the link and the model where the link is contained.

Returns: The URI of this entity.

Member Data Documentation

LinkPtr anchorLink

protectedinherited

Anchor link.

math::Vector3 anchorPos

protectedinherited

Anchor pose.

This is the xyz offset of the joint frame from child frame specified in the parent link frame

math::Pose anchorPose

protectedinherited

Anchor pose specified in SDF <joint><pose> tag.

AnchorPose is the transform from child link frame to joint frame specified in the child link frame. AnchorPos is more relevant in normal usage, but sometimes, we do need this (e.g. GetForceTorque and joint visualization).

gazebo::event::ConnectionPtr applyDamping

protectedinherited

apply damping for adding viscous damping forces on updates

bool axisParentModelFrame[2]

protectedinherited

Flags that are set to true if an axis value is expressed in the parent model frame.

Otherwise use the joint frame. See issue #494.

btDynamicsWorld* bulletWorld

protectedinherited

Pointer to Bullet's btDynamicsWorld.

LinkPtr childLink

protectedinherited

The first link this joint connects to.

Base_V children

protectedinherited

Children of this entity.

btTypedConstraint* constraint

protectedinherited

Pointer to a contraint object in Bullet.

double dissipationCoefficient[2]

protectedinherited

joint viscous damping coefficient

double effortLimit[2]

protectedinherited

Store Joint effort limit as specified in SDF.

math::Angle lowerLimit[2]

protectedinherited

Store Joint position lower limit as specified in SDF.

ModelPtr model

protectedinherited

Pointer to the parent model.

BasePtr parent

protectedinherited

Parent of this entity.

math::Pose parentAnchorPose

protectedinherited

Anchor pose relative to parent link frame.

LinkPtr parentLink

protectedinherited

The second link this joint connects to.

bool provideFeedback

protectedinherited

Provide Feedback data for contact forces.

sdf::ElementPtr sdf

protectedinherited

The SDF values for this object.

double springReferencePosition[2]

protectedinherited

joint spring reference (zero load) position

double stiffnessCoefficient[2]

protectedinherited

joint stiffnessCoefficient

math::Angle upperLimit[2]

protectedinherited

Store Joint position upper limit as specified in SDF.

double velocityLimit[2]

protectedinherited

Store Joint velocity limit as specified in SDF.

WorldPtr world

protectedinherited

Pointer to the world.

JointWrench wrench

protectedinherited

Cache Joint force torque values in case physics engine clears them at the end of update step.

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

BulletBallJoint.hh

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation