Defines a joint for purely rotational motion. More...

#include <SphericalJoint.h>

Inheritance diagram for SPHERICALJOINT:

Public Types
enum	Axis { eAxis1, eAxis2, eAxis3 }

Public Types inherited from JOINT
enum	ConstraintType { eUnknown, eExplicit, eImplicit }

enum	DOFs { DOF_1 =0, DOF_2 =1, DOF_3 =2, DOF_4 =3, DOF_5 =4, DOF_6 =5 }

Public Member Functions
	SPHERICALJOINT ()
	Initializes the joint. More...

virtual void	update_spatial_axes ()
	Updates the spatial axis for this joint.

virtual void	determine_q (VECTORN &q)
	Determines (and sets) the value of Q from the axes and the inboard link and outboard link transforms.

virtual boost::shared_ptr < const POSE3 >	get_induced_pose ()
	Gets the (local) transform for this joint.

virtual const std::vector < SVELOCITY > &	get_spatial_axes ()
	Gets the spatial axes for this joint. More...

virtual const std::vector < SVELOCITY > &	get_spatial_axes_dot ()
	Gets the derivative of the spatial-axis. More...

virtual unsigned	num_dof () const
	Gets the number of degrees-of-freedom for this joint.

virtual void	evaluate_constraints (REAL C[])
	Evaluates the constraint equations.

VECTOR3	get_axis (Axis a) const
	Gets the global axis for this joint. More...

void	set_axis (const VECTOR3 &axis, Axis a)
	Sets the local axis of rotation for this joint (MUST BE CALLED AFTER set_location(.)) More...

virtual void	calc_constraint_jacobian (bool inboard, MATRIXN &Cq)
	Computes the constraint jacobian with respect to a body.

virtual void	calc_constraint_jacobian_dot (bool inboard, MATRIXN &Cq)
	Computes the time derivative of the constraint jacobian with respect to a body. More...

virtual bool	is_singular_config () const
	Spherical joint is singular if sin(q1) = 0 and cos(q2) = 0.

Public Member Functions inherited from JOINT
	JOINT ()
	Initializes the joint. More...

void	add_force (const VECTORN &force)
	Adds a force to the joint.

void	reset_force ()
	Resets the force on the joint.

ConstraintType	get_constraint_type () const

void	set_constraint_type (ConstraintType type)
	Sets whether this constraint is implicit or explicit (or unknown)

boost::shared_ptr < ARTICULATED_BODY >	get_articulated_body ()
	Gets the articulated body corresponding to this body. More...

void	set_articulated_body (boost::shared_ptr< ARTICULATED_BODY > abody)
	Sets the articulated body corresponding to this body. More...

virtual void	set_inboard_link (boost::shared_ptr< RIGIDBODY > link, bool update_pose)

virtual void	set_outboard_link (boost::shared_ptr< RIGIDBODY > link, bool update_pose)

void	set_location (const VECTOR3 &p, boost::shared_ptr< RIGIDBODY > inboard, boost::shared_ptr< RIGIDBODY > outboard)

VECTOR3	get_location (bool use_outboard=false) const
	Gets the location of this joint. More...

virtual void	set_inboard_pose (boost::shared_ptr< const POSE3 > inboard_pose, bool update_joint_pose)

virtual void	set_outboard_pose (boost::shared_ptr< POSE3 > outboard_pose, bool update_joint_pose)

virtual void	evaluate_constraints_dot (REAL C[])
	Evaluates the time derivative of the constraint equations.

virtual void	set_q_tare (const VECTORN &tare)

virtual const VECTORN &	get_q_tare () const

boost::shared_ptr< RIGIDBODY >	get_inboard_link () const
	Gets the inboard link for this joint.

boost::shared_ptr< RIGIDBODY >	get_outboard_link () const
	Gets the outboard link for this joint.

unsigned	get_index () const
	Gets the joint index (returns UINT_MAX if not set)

void	set_index (unsigned index)
	Sets the joint index. More...

unsigned	get_constraint_index () const
	Gets the constraint index for this joint.

void	set_constraint_index (unsigned idx)
	Sets the constraint index for this joint.

void	set_coord_index (unsigned index)
	Sets the coordinate index for this joint. More...

unsigned	get_coord_index () const
	Gets the starting coordinate index for this joint.

boost::shared_ptr< const POSE3 >	get_pose () const
	Gets the pose of this joint (relative to the inboard pose instead of the outboard pose as returned by get_pose_from_outboard())

boost::shared_ptr< const POSE3 >	get_pose_from_outboard () const
	Gets the pose of this joint relative to the outboard pose (rather than the inboard pose as returned by get_pose())

virtual unsigned	num_constraint_eqns () const
	Gets the number of constraint equations for this joint.

Public Member Functions inherited from Ravelin::virtual_enable_shared_from_this< JOINT >
boost::shared_ptr< JOINT >	shared_from_this ()

boost::shared_ptr< const JOINT >	shared_from_this () const

Public Attributes
REAL	SINGULAR_TOL
	The tolerance to which a joint configuration is considered singular. More...

Public Attributes inherited from JOINT
std::string	joint_id
	The ID of this joint.

VECTORN	qdd
	The acceleration of this joint.

VECTORN	force
	The actuator force (user/controller sets this)

VECTORN	lambda
	Constraint forces calculated by forward dynamics.

VECTORN	q
	The position of this joint.

VECTORN	qd
	The velocity of this joint.

Protected Member Functions
bool	assign_axes ()
	Attempts to compute unassigned axes.

MATRIX3	get_rotation () const
	Gets the (local) rotation induced by this joint.

void	setup_joint ()

Protected Member Functions inherited from JOINT
void	calc_constraint_jacobian_numeric (bool inboard, MATRIXN &Cq)
	Computes the constraint jacobian with respect to a body numerically

bool	transform_jacobian (MATRIXN &J, bool use_inboard, MATRIXN &output)
	Transforms a Jacobian (if necessary) More...

void	invalidate_pose_vectors ()

boost::shared_ptr< const POSE3 >	get_inboard_pose ()

boost::shared_ptr< const POSE3 >	get_outboard_pose ()

virtual void	init_data ()
	Method for initializing all variables in the joint. More...

Static Protected Member Functions
static bool	rel_equal (REAL x, REAL y)
	Determines whether two values are relatively equal.

Protected Attributes
VECTOR3	_u [3]
	The local joint axes.

std::vector< SVELOCITY >	_s_dot
	The derivative of the spatial axis.

Protected Attributes inherited from JOINT
boost::shared_ptr< POSE3 >	_Fprime
	The frame induced by the joint.

boost::shared_ptr< POSE3 >	_F
	The frame of this joint.

boost::shared_ptr< POSE3 >	_Fb
	The frame of this joint backward from the outboard link.

std::vector< SVELOCITY >	_s
	The spatial axes (in joint frame) for the joint. More...

VECTORN	_q_tare
	The stored "tare" value for the initial joint configuration. More...

boost::weak_ptr< RIGIDBODY >	_inboard_link

boost::weak_ptr< RIGIDBODY >	_outboard_link

boost::weak_ptr< ARTICULATED_BODY >	_abody

ConstraintType	_constraint_type

unsigned	_joint_idx

unsigned	_coord_idx

unsigned	_constraint_idx

Detailed Description

Defines a joint for purely rotational motion.

Constructor & Destructor Documentation

SPHERICALJOINT::SPHERICALJOINT ( )

Initializes the joint.

The axes of rotation are each set to [0 0 0]. The inboard and outboard links are set to NULL.

References JOINT::_F, _s_dot, _u, JOINT::init_data(), num_dof(), VECTOR3::pose, and SINGULAR_TOL.

Member Function Documentation

void SPHERICALJOINT::calc_constraint_jacobian_dot	(	bool	inboard,
		MATRIXN &	Cq
	)

virtual

Computes the time derivative of the constraint jacobian with respect to a body.

TODO: implement this

Implements JOINT.

VECTOR3 SPHERICALJOINT::get_axis ( Axis a ) const

Gets the global axis for this joint.

The global axis for this joint takes the orientation of the inboard link into account; thus, if the orientation of the inboard link changes, then the global axis changes.

See Also: getAxisLocal(); setAxisLocal()

References JOINT::_q_tare, _u, VECTOR3::pose, and JOINT::q.

const vector< SVELOCITY > & SPHERICALJOINT::get_spatial_axes ( )

virtual

Gets the spatial axes for this joint.

Note: these spatial axes are not constant, unlike many joints.

Reimplemented from JOINT.

References JOINT::_q_tare, JOINT::_s, _u, JOINT::get_pose(), JOINT::get_spatial_axes(), and JOINT::q.

const vector< SVELOCITY > & SPHERICALJOINT::get_spatial_axes_dot ( )

virtual

Gets the derivative of the spatial-axis.

Note: these spatial axes are not constant, unlike many joints.

Implements JOINT.

References JOINT::_q_tare, _s_dot, _u, ORIGIN3::cross(), JOINT::get_pose(), JOINT::q, and JOINT::qd.

void SPHERICALJOINT::set_axis	(	const VECTOR3 &	axis,
		Axis	a
	)

Sets the local axis of rotation for this joint (MUST BE CALLED AFTER set_location(.))

The local axis for this joint does not take the orientation of the inboard link into account; thus, if the orientation of the inboard link changes, then the local axis remains constant.

Parameters

axis	a unit vector

See Also: get_axis_global(); set_axis_global()

References _u, JOINT::get_pose(), and update_spatial_axes().

Member Data Documentation

REAL SPHERICALJOINT::SINGULAR_TOL

The tolerance to which a joint configuration is considered singular.

Note: if this tolerance is too low, then dynamics computation may become unstable; if the tolerance is too high, then dynamics computation will be slower. A safe value is 1e-2.

Referenced by is_singular_config(), and SPHERICALJOINT().

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

/home/drum/Ravelin.new/include/Ravelin/SphericalJoint.h
/home/drum/Ravelin.new/src/SphericalJoint.cpp

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation