SimbodyJoint Class Referenceabstract

Base class for all joints. More...

#include <SimbodyJoint.hh>

Inherits Joint.

Inherited by BallJoint< SimbodyJoint >, FixedJoint< SimbodyJoint >, Hinge2Joint< SimbodyJoint >, HingeJoint< SimbodyJoint >, ScrewJoint< SimbodyJoint >, SliderJoint< SimbodyJoint >, and UniversalJoint< SimbodyJoint >.

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

 SimbodyJoint (BasePtr _parent)
 Constructor. More...
 
virtual ~SimbodyJoint ()
 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...
 
virtual 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 links. 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...
 
virtual 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 =0
 Get the angle count. More...
 
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 =0
 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...
 
virtual LinkPtr GetJointLink (unsigned int _index) const
 Get the link to which the joint is attached according the _index. More...
 
virtual math::Vector3 GetLinkForce (unsigned int _index) const
 Get the forces applied to the center of mass of a physics::Link due to the existence of this Joint. More...
 
virtual math::Vector3 GetLinkTorque (unsigned int _index) const
 Get the torque applied to the center of mass of a physics::Link due to the existence of this Joint. 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 =0
 Get the rotation rate of an axis(index) More...
 
virtual double GetVelocityLimit (unsigned int _index)
 Get the velocity limit on axis(index). More...
 
const WorldPtrGetWorld () 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 a joint. More...
 
bool IsSelected () const
 True if the entity is selected by the user. More...
 
virtual void Load (sdf::ElementPtr _sdf)
 Load physics::Joint from a SDF sdf::Element. 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 RestoreSimbodyState (SimTK::State &_state)
 
virtual void SaveSimbodyState (const SimTK::State &_state)
 
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, const 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 _vel)=0
 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...
 

Public Attributes

SimTK::Constraint constraint
 : isValid() if we used a constraint to model this joint. More...
 
SimTK::Force::MobilityLinearDamper damper [MAX_JOINT_AXIS]
 : for enforcing joint damping forces. More...
 
SimTK::Transform defxAB
 default mobilizer pose More...
 
bool isReversed
 : if mobilizer, did it reverse parent&child? Set when we build the Simbody model. More...
 
SimTK::Force::MobilityLinearStop limitForce [MAX_JOINT_AXIS]
 : for enforcing joint stops Set when we build the Simbody model. More...
 
SimTK::MobilizedBody mobod
 Use isValid() if we used a mobilizer Set when we build the Simbody model. More...
 
bool mustBreakLoopHere
 Force Simbody to break a loop by using a weld constraint. More...
 
bool physicsInitialized
 
SimTK::Force::MobilityLinearSpring spring [MAX_JOINT_AXIS]
 : Spring force element for enforcing joint stiffness. More...
 
SimTK::Transform xCB
 child body frame to mobilizer frame More...
 
SimTK::Transform xPA
 Normally A=F, B=M. 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 math::Angle GetAngleImpl (unsigned int _index) const =0
 Get the angle of an axis helper function. More...
 
virtual void SetForceImpl (unsigned int _index, double _force)=0
 Set the force applied to this physics::Joint. More...
 
bool SetPositionMaximal (unsigned int _index, double _position)
 Helper function for maximal coordinate solver SetPosition. 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...
 
LinkPtr childLink
 The first link this joint connects to. More...
 
Base_V children
 Children of this entity. 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...
 
SimbodyPhysicsPtr simbodyPhysics
 keep a pointer to the simbody physics engine for convenience 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...
 
SimTK::MultibodySystem * world
 Simbody Multibody System. More...
 
JointWrench wrench
 Cache Joint force torque values in case physics engine clears them at the end of update step. More...
 

Detailed Description

Base class for all joints.

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

SimbodyJoint ( BasePtr  _parent)

Constructor.

virtual ~SimbodyJoint ( )
virtual

Destructor.

Member Function Documentation

void AddChild ( BasePtr  _child)
inherited

Add a child to this entity.

Parameters
[in]_childChild entity.
void AddType ( EntityType  _type)
inherited

Add a type specifier.

Parameters
[in]_typeNew 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 in ODEJoint, and BulletJoint.

virtual bool AreConnected ( LinkPtr  _one,
LinkPtr  _two 
) const
virtual

Determines of the two bodies are connected by a joint.

Parameters
[in]_oneFirst link.
[in]_twoSecond link.
Returns
True if the two links are connected by a joint.

Implements Joint.

virtual void Attach ( LinkPtr  _parent,
LinkPtr  _child 
)
virtualinherited

Attach the two bodies with this joint.

Parameters
[in]_parentParent link.
[in]_childChild link.

Reimplemented in ODEJoint, ODEFixedJoint, and DARTJoint.

virtual void CacheForceTorque ( )
virtual

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]_indexIndex of the axis.
[in]_effortForce 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]_indexaxis index
[in]_positionnew 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 ( _subscriber)
inlineinherited

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

Parameters
[in]_subscriberCallback for the connection.
Returns
Connection pointer, which must be kept in scope.

References EventT< T >::Connect().

virtual void Detach ( )
virtual

Detach this joint from all links.

Reimplemented from Joint.

void DisconnectJointUpdate ( event::ConnectionPtr _conn)
inlineinherited

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

Parameters
[in]_connConnection to disconnect.

References EventT< T >::Disconnect().

virtual void FillMsg ( msgs::Joint &  _msg)
virtualinherited

Fill a joint message.

Parameters
[out]_msgMessage 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]_originalParentLinkparent 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 Base.

Reimplemented in ODEJoint, and BulletJoint.

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

Get the anchor point.

Parameters
[in]_indexIndex of the axis.
Returns
Anchor value for the axis.

Implements Joint.

Reimplemented in SimbodyHinge2Joint, SimbodyUniversalJoint, and SimbodyBallJoint.

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]_indexIndex of the axis.
Returns
Angle of the axis.
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]_indexjoint 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]_indexjoint 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]_nameGet 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]_iIndex 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]_nameName 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]_indexIndex 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]_indexIndex of axis, where 0=first axis and 1=second axis
Returns
Effort limit specified in SDF
virtual double GetForce ( unsigned int  _index)
virtual
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]_indexIndex of the axis.
Returns
The force applied to an axis.

Reimplemented from Joint.

virtual JointWrench GetForceTorque ( unsigned int  _index)
virtual

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]_indexNot used right now
Returns
The force and torque at the joint, see above for details on conventions.

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]_indexIndex of the axis.
Returns
Angle of the high stop value.

Implements Joint.

Reimplemented in SimbodyBallJoint, and SimbodyScrewJoint.

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]_indexaxis 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]_axisaxis 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.
virtual LinkPtr GetJointLink ( unsigned int  _index) const
virtual

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

Parameters
[in]_indexIndex of the link to retreive.
Returns
Pointer to the request link. NULL if the index was invalid.

Implements Joint.

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

Get the forces applied to the center of mass of a physics::Link due to the existence of this Joint.

Note that the unit of force should be consistent with the rest of the simulation scales.

Parameters
[in]indexThe index of the link(0 or 1).
Returns
Force applied to the link.

Implements Joint.

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

Get the torque applied to the center of mass of a physics::Link due to the existence of this Joint.

Note that the unit of torque should be consistent with the rest of the simulation scales.

Parameters
[in]indexThe index of the link(0 or 1)
Returns
Torque applied to the link.

Implements Joint.

math::Vector3 GetLocalAxis ( unsigned int  _index) const
inherited

Get the axis of rotation.

Parameters
[in]_indexIndex 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]_indexIndex 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]_indexIndex of the axis.
Returns
Angle of the low stop value.

Implements Joint.

Reimplemented in SimbodyBallJoint, and SimbodyScrewJoint.

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 
)
virtual

Get a non-generic parameter for the joint.

See Also
SetParam(const std::string &, unsigned int, const boost::any)
Parameters
[in]_keyString key.
[in]_indexIndex of the axis.

Reimplemented from Joint.

Reimplemented in SimbodyScrewJoint.

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]_prependWorldNameTrue 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]_indexIndex 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]_indexIndex 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]_indexjoint axis index.
Returns
joint stop dissipation coefficient.
double GetStopStiffness ( unsigned int  _index) const
inherited

Get joint stop stiffness.

Parameters
[in]_indexjoint 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]_indexIndex of the axis.
Returns
Upper limit of the axis.
virtual double GetVelocityLimit ( unsigned int  _index)
virtualinherited

Get the velocity limit on axis(index).

Parameters
[in]_indexIndex 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]_tType to check.
Returns
True if this object's type definition has the.
bool IsSelected ( ) const
inherited

True if the entity is selected by the user.

Returns
True if the entity is selected.
void Load ( LinkPtr  _parent,
LinkPtr  _child,
const math::Pose _pose 
)
inherited

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

Parameters
[in]_parentParent link.
[in]_childChild link.
[in]_posePose 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]_entBase 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]_prefixUsually a set of spaces.
virtual void RemoveChild ( unsigned int  _id)
virtualinherited

Remove a child from this entity.

Parameters
[in]_idID of the child to remove.
void RemoveChild ( const std::string &  _name)
inherited

Remove a child by name.

Parameters
[in]_nameName of the child.
void RemoveChildren ( )
inherited

Remove all children.

virtual void Reset ( )
virtual

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]_resetTypeThe type of reset operation
virtual void RestoreSimbodyState ( SimTK::State &  _state)
virtual

Reimplemented in SimbodyHingeJoint.

virtual void SaveSimbodyState ( const SimTK::State &  _state)
virtual

Reimplemented in SimbodyHingeJoint.

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

Set the anchor point.

Parameters
[in]_indexIndx of the axis.
[in]_anchorAnchor value.

Implements Joint.

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]_indexIndex of the axis to set.
[in]_axisVector in local joint frame of axis direction (must have length greater than zero).

Implements Joint.

Reimplemented in SimbodyBallJoint, SimbodyHinge2Joint, SimbodyUniversalJoint, SimbodyHingeJoint, SimbodyScrewJoint, and SimbodySliderJoint.

virtual void SetDamping ( unsigned int  _index,
const double  _damping 
)
virtual

Set the joint damping.

Parameters
[in]_indexIndex of the axis to set, currently ignored, to be implemented.
[in]_dampingDamping value for the axis.

Implements Joint.

virtual void SetEffortLimit ( unsigned int  _index,
double  _effort 
)
virtualinherited

Set the effort limit on a joint axis.

Parameters
[in]_indexIndex of the axis to set.
[in]_effortEffort limit for the axis.
virtual void SetForce ( unsigned int  _index,
double  _effort 
)
virtual

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]_indexIndex of the axis.
[in]_effortForce value.

Implements Joint.

virtual void SetForceImpl ( unsigned int  _index,
double  _force 
)
protectedpure virtual

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

Implemented in SimbodyScrewJoint, SimbodyBallJoint, SimbodyHinge2Joint, SimbodyUniversalJoint, SimbodyHingeJoint, SimbodySliderJoint, and SimbodyFixedJoint.

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

Set the high stop of an axis(index).

Parameters
[in]_indexIndex of the axis.
[in]_angleHigh stop angle.

Reimplemented from Joint.

Reimplemented in SimbodyBallJoint, and SimbodyScrewJoint.

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

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

Parameters
[in]_indexIndex of the axis.
[in]_limitLower 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]_indexIndex of the axis.
[in]_angleLow stop angle.

Reimplemented from Joint.

Reimplemented in SimbodyBallJoint, and SimbodyScrewJoint.

void SetModel ( ModelPtr  _model)
inherited

Set the model this joint belongs too.

Parameters
[in]_modelPointer to a model.
virtual void SetName ( const std::string &  _name)
virtualinherited

Set the name of the entity.

Parameters
[in]_nameNew name.

Reimplemented in Entity.

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

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]_keyString key.
[in]_indexIndex of the axis.
[in]_valueValue of the attribute.

Implements Joint.

Reimplemented in SimbodyScrewJoint.

void SetParent ( BasePtr  _parent)
inherited

Set the parent.

Parameters
[in]_parentParent 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]_indexIndex of the joint axis (degree of freedom).
[in]_positionPosition to set the joint to. unspecified, pure kinematic teleportation.
Returns
returns true if operation succeeds, false if it fails.

Reimplemented in ODEJoint, and BulletJoint.

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]_indexIndex of the joint axis (degree of freedom).
[in]_positionPosition 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]_enableTrue to enable joint feedback.

Reimplemented in ODEJoint, and BulletJoint.

void SetSaveable ( bool  _v)
inherited

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

Parameters
[in]_vSet 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]_showTrue to set this entity as selected.

Reimplemented in Link.

void SetState ( const JointState _state)
inherited

Set the joint state.

Parameters
[in]_stateJoint state
virtual void SetStiffness ( unsigned int  _index,
const double  _stiffness 
)
virtual

Set the joint spring stiffness.

Parameters
[in]_indexIndex of the axis to set, currently ignored, to be implemented.
[in]_stiffnessSpring stiffness value for the axis. : rename to SetSpringStiffness()

Implements Joint.

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

Set the joint spring stiffness.

Parameters
[in]_indexIndex of the axis to set, currently ignored, to be implemented.
[in]_stiffnessStiffness value for the axis.
[in]_referenceSpring zero load reference position. : rename to SetSpringStiffnessDamping()

Implements Joint.

void SetStopDissipation ( unsigned int  _index,
double  _dissipation 
)
inherited

Set joint stop dissipation.

Parameters
[in]_indexjoint axis index.
[in]_dissipationjoint stop dissipation coefficient.
void SetStopStiffness ( unsigned int  _index,
double  _stiffness 
)
inherited

Set joint stop stiffness.

Parameters
[in]_indexjoint axis index.
[in]_stiffnessjoint stop stiffness coefficient.
void SetUpperLimit ( unsigned int  _index,
math::Angle  _limit 
)
inherited

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

Parameters
[in]_indexIndex of the axis.
[in]_limitUpper limit of the axis.
virtual void SetVelocity ( unsigned int  _index,
double  _vel 
)
pure virtualinherited

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]_indexIndex of the axis.
[in]_velVelocity.

Implemented in BulletScrewJoint, DARTScrewJoint, SimbodyScrewJoint, ODEScrewJoint, BulletSliderJoint, BulletHinge2Joint, ODEGearboxJoint, ODEHinge2Joint, ODEHingeJoint, ODESliderJoint, DARTHinge2Joint, ODEUniversalJoint, ODEFixedJoint, DARTUniversalJoint, DARTFixedJoint, DARTHingeJoint, SimbodyHinge2Joint, BulletBallJoint, DARTSliderJoint, BulletHingeJoint, SimbodyUniversalJoint, BulletUniversalJoint, BulletFixedJoint, ODEBallJoint, SimbodyFixedJoint, DARTBallJoint, SimbodyBallJoint, SimbodyHingeJoint, and SimbodySliderJoint.

virtual void SetVelocityLimit ( unsigned int  _index,
double  _velocity 
)
virtualinherited

Set the velocity limit on a joint axis.

Parameters
[in]_indexIndex of the axis to set.
[in]_velocityVelocity 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]_indexIndex of the joint axis (degree of freedom).
[in]_velocityVelocity 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]_newWorldThe 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]_sdfSDF 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.

LinkPtr childLink
protectedinherited

The first link this joint connects to.

Base_V children
protectedinherited

Children of this entity.

SimTK::Constraint constraint

: isValid() if we used a constraint to model this joint.

Set when we build the Simbody model. How this joint was modeled in the Simbody System. We used either a mobilizer or a constraint, but not both. The type of either one is the same as the joint type above.

SimTK::Force::MobilityLinearDamper damper[MAX_JOINT_AXIS]

: for enforcing joint damping forces.

Set when we build the Simbody model. : Also, consider moving this into individual joint type subclass so we can specify custom dampers for special joints like ball joints.

SimTK::Transform defxAB

default mobilizer pose

double dissipationCoefficient[2]
protectedinherited

joint viscous damping coefficient

double effortLimit[2]
protectedinherited

Store Joint effort limit as specified in SDF.

bool isReversed

: if mobilizer, did it reverse parent&child? Set when we build the Simbody model.

SimTK::Force::MobilityLinearStop limitForce[MAX_JOINT_AXIS]

: for enforcing joint stops Set when we build the Simbody model.

: Also, consider moving this into individual joint type subclass so we can specify custom dampers for special joints like ball joints. Assuming this is not used for BallJoints it's ok here for now.

math::Angle lowerLimit[2]
protectedinherited

Store Joint position lower limit as specified in SDF.

SimTK::MobilizedBody mobod

Use isValid() if we used a mobilizer Set when we build the Simbody model.

How this joint was modeled in the Simbody System. We used either a mobilizer or a constraint, but not both. The type of either one is the same as the joint type above.

ModelPtr model
protectedinherited

Pointer to the parent model.

bool mustBreakLoopHere

Force Simbody to break a loop by using a weld constraint.

This flag is needed by SimbodyPhysics::MultibodyGraphMaker, so kept public.

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 physicsInitialized
bool provideFeedback
protectedinherited

Provide Feedback data for contact forces.

sdf::ElementPtr sdf
protectedinherited

The SDF values for this object.

SimbodyPhysicsPtr simbodyPhysics
protected

keep a pointer to the simbody physics engine for convenience

SimTK::Force::MobilityLinearSpring spring[MAX_JOINT_AXIS]

: Spring force element for enforcing joint stiffness.

The element is assigned when constructing Simbody model in SimbodyPhysics::AddDynamicModelToSimbodySystem. : Also, consider moving this into individual joint type subclass so we can specify custom springs for special joints like ball joints.

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.

SimTK::MultibodySystem* world
protected

Simbody Multibody System.

JointWrench wrench
protectedinherited

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

SimTK::Transform xCB

child body frame to mobilizer frame

SimTK::Transform xPA

Normally A=F, B=M.

But if reversed, then B=F, A=M. parent body frame to mobilizer frame


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