Contains all information about the rigid body model. More...

Public Member Functions
	Model ()

unsigned int	AddBody (const unsigned int parent_id, const Math::SpatialTransform &joint_frame, const Joint &joint, const Body &body, std::string body_name="")
	Connects a given body to the model. More...

unsigned int	AddBodySphericalJoint (const unsigned int parent_id, const Math::SpatialTransform &joint_frame, const Joint &joint, const Body &body, std::string body_name="")

unsigned int	AppendBody (const Math::SpatialTransform &joint_frame, const Joint &joint, const Body &body, std::string body_name="")
	Adds a Body to the model such that the previously added Body is the Parent. More...

unsigned int	AddBodyCustomJoint (const unsigned int parent_id, const Math::SpatialTransform &joint_frame, CustomJoint *custom_joint, const Body &body, std::string body_name="")

unsigned int	GetBodyId (const char *body_name) const
	Returns the id of a body that was passed to AddBody() More...

std::string	GetBodyName (unsigned int body_id) const
	Returns the name of a body for a given body id. More...

bool	IsFixedBodyId (unsigned int body_id)
	Checks whether the body is rigidly attached to another body. More...

bool	IsBodyId (unsigned int id)

unsigned int	GetParentBodyId (unsigned int id)

Math::SpatialTransform	GetJointFrame (unsigned int id)

void	SetJointFrame (unsigned int id, const Math::SpatialTransform &transform)

Math::Quaternion	GetQuaternion (unsigned int i, const Math::VectorNd &Q) const

void	SetQuaternion (unsigned int i, const Math::Quaternion &quat, Math::VectorNd &Q) const

Data Fields
std::vector< unsigned int >	lambda
	The id of the parents body. More...

std::vector< unsigned int >	lambda_q
	The index of the parent degree of freedom that is directly influencing the current one. More...

std::vector< std::vector< unsigned int > >	mu
	Contains the ids of all the children of a given body. More...

unsigned int	dof_count
	number of degrees of freedoms of the model More...

unsigned int	q_size
	The size of the $\mathbf{q}$ -vector. For models without spherical joints the value is the same as Model::dof_count, otherwise additional values for the w-component of the Quaternion is stored at the end of $\mathbf{q}$ . More...

unsigned int	qdot_size
	The size of the. More...

unsigned int	previously_added_body_id
	Id of the previously added body, required for Model::AppendBody() More...

Math::Vector3d	gravity
	the cartesian vector of the gravity More...

std::vector< Math::SpatialVector >	v
	The spatial velocity of the bodies. More...

std::vector< Math::SpatialVector >	a
	The spatial acceleration of the bodies. More...

std::vector< Joint >	mJoints
	All joints. More...

std::vector< Math::SpatialVector >	S
	The joint axis for joint i. More...

std::vector< Math::SpatialVector >	v_J

std::vector< Math::SpatialVector >	c_J

std::vector< unsigned int >	mJointUpdateOrder

std::vector< Math::SpatialTransform >	X_T
	Transformations from the parent body to the frame of the joint. More...

std::vector< unsigned int >	mFixedJointCount
	The number of fixed joints that have been declared before each joint. More...

std::vector< Math::Matrix63 >	multdof3_S
	Motion subspace for joints with 3 degrees of freedom. More...

std::vector< Math::Matrix63 >	multdof3_U

std::vector< Math::Matrix3d >	multdof3_Dinv

std::vector< Math::Vector3d >	multdof3_u

std::vector< unsigned int >	multdof3_w_index

std::vector< CustomJoint * >	mCustomJoints

std::vector< Math::SpatialVector >	c
	The velocity dependent spatial acceleration. More...

std::vector< Math::SpatialMatrix >	IA
	The spatial inertia of the bodies. More...

std::vector< Math::SpatialVector >	pA
	The spatial bias force. More...

std::vector< Math::SpatialVector >	U
	Temporary variable U_i (RBDA p. 130) More...

Math::VectorNd	d
	Temporary variable D_i (RBDA p. 130) More...

Math::VectorNd	u
	Temporary variable u (RBDA p. 130) More...

std::vector< Math::SpatialVector >	f
	Internal forces on the body (used only InverseDynamics()) More...

std::vector< Math::SpatialRigidBodyInertia >	I
	The spatial inertia of body i (used only in CompositeRigidBodyAlgorithm()) More...

std::vector< Math::SpatialRigidBodyInertia >	Ic

std::vector< Math::SpatialVector >	hc

std::vector< Math::SpatialVector >	hdotc

std::vector< Math::SpatialTransform >	X_lambda
	Transformation from the parent body to the current body $X_{\lambda(i)} = {}^{i} X_{\lambda(i)}$ . More...

std::vector< Math::SpatialTransform >	X_base
	Transformation from the base to bodies reference frame. More...

std::vector< FixedBody >	mFixedBodies
	All bodies that are attached to a body via a fixed joint. More...

unsigned int	fixed_body_discriminator
	Value that is used to discriminate between fixed and movable bodies. More...

std::vector< Body >	mBodies
	All bodies 0 ... N_B, including the base. More...

std::map< std::string, unsigned int >	mBodyNameMap
	Human readable names for the bodies. More...

Detailed Description

Contains all information about the rigid body model.

This class contains all information required to perform the forward dynamics calculation. The variables in this class are also used for storage of temporary values. It is designed for use of the Articulated Rigid Body Algorithm (which is implemented in ForwardDynamics()) and follows the numbering as described in Featherstones book.

Please note that body 0 is the root body and the moving bodies start at index 1. This numbering scheme is very beneficial in terms of readability of the code as the resulting code is very similar to the pseudo-code in the RBDA book. The generalized variables q, qdot, qddot and tau however start at 0 such that the first entry (e.g. q[0]) always specifies the value for the first moving body.

Note: To query the number of degrees of freedom use Model::dof_count.

Definition at line 121 of file Model.h.

Constructor & Destructor Documentation

◆ Model()

Model ( )

Definition at line 23 of file Model.cc.

Member Function Documentation

◆ AddBody()

unsigned int AddBody	(	const unsigned int	parent_id,
		const Math::SpatialTransform &	joint_frame,
		const Joint &	joint,
		const Body &	body,
		std::string	body_name = `""`
	)

Connects a given body to the model.

When adding a body there are basically informations required:

what kind of body will be added?
where is the new body to be added?
by what kind of joint should the body be added?

The first information "what kind of body will be added" is contained in the Body class that is given as a parameter.

The question "where is the new body to be added?" is split up in two parts: first the parent (or successor) body to which it is added and second the transformation to the origin of the joint that connects the two bodies. With these two informations one specifies the relative positions of the bodies when the joint is in neutral position.gk

The last question "by what kind of joint should the body be added?" is again simply contained in the Joint class.

Parameters

parent_id	id of the parent body
joint_frame	the transformation from the parent frame to the origin of the joint frame (represents X_T in RBDA)
joint	specification for the joint that describes the connection
body	specification of the body itself
body_name	human readable name for the body (can be used to retrieve its id with GetBodyId())

Returns: id of the added body

Definition at line 249 of file Model.cc.

◆ AddBodyCustomJoint()

unsigned int AddBodyCustomJoint	(	const unsigned int	parent_id,
		const Math::SpatialTransform &	joint_frame,
		CustomJoint *	custom_joint,
		const Body &	body,
		std::string	body_name = `""`
	)

Definition at line 473 of file Model.cc.

References Joint::custom_joint_index, RigidBodyDynamics::JointTypeCustom, and CustomJoint::mDoFCount.

◆ AddBodySphericalJoint()

unsigned int AddBodySphericalJoint	(	const unsigned int	parent_id,
		const Math::SpatialTransform &	joint_frame,
		const Joint &	joint,
		const Body &	body,
		std::string	body_name = `""`
	)

◆ AppendBody()

unsigned int AppendBody	(	const Math::SpatialTransform &	joint_frame,
		const Joint &	joint,
		const Body &	body,
		std::string	body_name = `""`
	)

Adds a Body to the model such that the previously added Body is the Parent.

This function is basically the same as Model::AddBody() however the most recently added body (or body 0) is taken as parent.

Definition at line 460 of file Model.cc.

References Model::AddBody().

◆ GetBodyId()

unsigned int GetBodyId ( const char * body_name ) const

inline

Returns the id of a body that was passed to AddBody()

Bodies can be given a human readable name. This function allows to resolve its name to the numeric id.

Note: Instead of querying this function repeatedly, it might be advisable to query it once and reuse the returned id.

Returns: the id of the body or std::numeric_limits<unsigned int>::max() if the id was not found.

Definition at line 345 of file Model.h.

◆ GetBodyName()

std::string GetBodyName ( unsigned int body_id ) const

inline

Returns the name of a body for a given body id.

Definition at line 354 of file Model.h.

◆ GetJointFrame()

Math::SpatialTransform GetJointFrame ( unsigned int id )

inline

Returns the joint frame transformtion, i.e. the second argument to Model::AddBody().

Definition at line 414 of file Model.h.

◆ GetParentBodyId()

unsigned int GetParentBodyId ( unsigned int id )

inline

Determines id the actual parent body.

When adding bodies using joints with multiple degrees of freedom, additional virtual bodies are added for each degree of freedom. This function returns the id of the actual non-virtual parent body.

Definition at line 397 of file Model.h.

◆ GetQuaternion()

Math::Quaternion GetQuaternion	(	unsigned int	i,
		const Math::VectorNd &	Q
	)		const

inline

Gets the quaternion for body i (only valid if body i is connected by a JointTypeSpherical joint)

See Joint Singularities for details.

Definition at line 460 of file Model.h.

References RigidBodyDynamics::JointTypeSpherical.

◆ IsBodyId()

bool IsBodyId ( unsigned int id )

inline

Definition at line 379 of file Model.h.

◆ IsFixedBodyId()

bool IsFixedBodyId ( unsigned int body_id )

inline

Checks whether the body is rigidly attached to another body.

Definition at line 370 of file Model.h.

◆ SetJointFrame()

void SetJointFrame	(	unsigned int	id,
		const Math::SpatialTransform &	transform
	)

inline

Sets the joint frame transformtion, i.e. the second argument to Model::AddBody().

Definition at line 434 of file Model.h.

◆ SetQuaternion()

void SetQuaternion	(	unsigned int	i,
		const Math::Quaternion &	quat,
		Math::VectorNd &	Q
	)		const

inline

Sets the quaternion for body i (only valid if body i is connected by a JointTypeSpherical joint)

See Joint Singularities for details.

Definition at line 475 of file Model.h.

References RigidBodyDynamics::JointTypeSpherical.

Field Documentation

◆ a

std::vector<Math::SpatialVector> a

The spatial acceleration of the bodies.

Definition at line 168 of file Model.h.

◆ c

std::vector<Math::SpatialVector> c

The velocity dependent spatial acceleration.

Definition at line 207 of file Model.h.

◆ c_J

std::vector<Math::SpatialVector> c_J

Definition at line 181 of file Model.h.

◆ d

Math::VectorNd d

Temporary variable D_i (RBDA p. 130)

Definition at line 215 of file Model.h.

◆ dof_count

unsigned int dof_count

number of degrees of freedoms of the model

This value contains the number of entries in the generalized state (q) velocity (qdot), acceleration (qddot), and force (tau) vector.

Definition at line 139 of file Model.h.

◆ f

std::vector<Math::SpatialVector> f

Internal forces on the body (used only InverseDynamics())

Definition at line 219 of file Model.h.

◆ fixed_body_discriminator

unsigned int fixed_body_discriminator

Value that is used to discriminate between fixed and movable bodies.

Bodies with id 1 .. (fixed_body_discriminator - 1) are moving bodies while bodies with id fixed_body_discriminator .. max (unsigned int) are fixed to a moving body. The value of max(unsigned int) is determined via std::numeric_limits<unsigned int>::max() and the default value of fixed_body_discriminator is max (unsigned int) / 2.

On normal systems max (unsigned int) is 4294967294 which means there could be a total of 2147483646 movable and / or fixed bodies.

Definition at line 253 of file Model.h.

◆ gravity

Math::Vector3d gravity

the cartesian vector of the gravity

Definition at line 162 of file Model.h.

◆ hc

std::vector<Math::SpatialVector> hc

Definition at line 224 of file Model.h.

◆ hdotc

std::vector<Math::SpatialVector> hdotc

Definition at line 225 of file Model.h.

◆ I

std::vector<Math::SpatialRigidBodyInertia> I

The spatial inertia of body i (used only in CompositeRigidBodyAlgorithm())

Definition at line 222 of file Model.h.

◆ IA

std::vector<Math::SpatialMatrix> IA

The spatial inertia of the bodies.

Definition at line 209 of file Model.h.

◆ Ic

std::vector<Math::SpatialRigidBodyInertia> Ic

Definition at line 223 of file Model.h.

◆ lambda

std::vector<unsigned int> lambda

The id of the parents body.

Definition at line 127 of file Model.h.

◆ lambda_q

std::vector<unsigned int> lambda_q

The index of the parent degree of freedom that is directly influencing the current one.

Definition at line 130 of file Model.h.

◆ mBodies

std::vector<Body> mBodies

All bodies 0 ... N_B, including the base.

mBodies[0] - base body
mBodies[1] - 1st moveable body
...
mBodies[N_B] - N_Bth moveable body

Definition at line 262 of file Model.h.

◆ mBodyNameMap

std::map<std::string, unsigned int> mBodyNameMap

Human readable names for the bodies.

Definition at line 265 of file Model.h.

◆ mCustomJoints

std::vector<CustomJoint*> mCustomJoints

Definition at line 201 of file Model.h.

◆ mFixedBodies

std::vector<FixedBody> mFixedBodies

All bodies that are attached to a body via a fixed joint.

Definition at line 240 of file Model.h.

◆ mFixedJointCount

std::vector<unsigned int> mFixedJointCount

The number of fixed joints that have been declared before each joint.

Definition at line 190 of file Model.h.

◆ mJoints

std::vector<Joint> mJoints

All joints.

Definition at line 175 of file Model.h.

◆ mJointUpdateOrder

std::vector<unsigned int> mJointUpdateOrder

Definition at line 183 of file Model.h.

◆ mu

std::vector<std::vector<unsigned int> > mu

Contains the ids of all the children of a given body.

Definition at line 132 of file Model.h.

◆ multdof3_Dinv

std::vector<Math::Matrix3d> multdof3_Dinv

Definition at line 197 of file Model.h.

◆ multdof3_S

std::vector<Math::Matrix63> multdof3_S

Motion subspace for joints with 3 degrees of freedom.

Definition at line 195 of file Model.h.

◆ multdof3_U

std::vector<Math::Matrix63> multdof3_U

Definition at line 196 of file Model.h.

◆ multdof3_u

std::vector<Math::Vector3d> multdof3_u

Definition at line 198 of file Model.h.

◆ multdof3_w_index

std::vector<unsigned int> multdof3_w_index

Definition at line 199 of file Model.h.

◆ pA

std::vector<Math::SpatialVector> pA

The spatial bias force.

Definition at line 211 of file Model.h.

◆ previously_added_body_id

unsigned int previously_added_body_id

Id of the previously added body, required for Model::AppendBody()

Definition at line 159 of file Model.h.

◆ q_size

unsigned int q_size

The size of the $\mathbf{q}$ -vector. For models without spherical joints the value is the same as Model::dof_count, otherwise additional values for the w-component of the Quaternion is stored at the end of $\mathbf{q}$ .

See also: Joint Modeling for more details.

Definition at line 148 of file Model.h.

◆ qdot_size

unsigned int qdot_size

The size of the.

( $\mathbf{\dot{q}}, \mathbf{\ddot{q}}$ , and $\mathbf{\tau}$ -vector.

See also: Joint Modeling for more details.

Definition at line 156 of file Model.h.

◆ S

std::vector<Math::SpatialVector> S

The joint axis for joint i.

Definition at line 177 of file Model.h.

◆ U

std::vector<Math::SpatialVector> U

Temporary variable U_i (RBDA p. 130)

Definition at line 213 of file Model.h.

◆ u

Math::VectorNd u

Temporary variable u (RBDA p. 130)

Definition at line 217 of file Model.h.

◆ v

std::vector<Math::SpatialVector> v

The spatial velocity of the bodies.

Definition at line 166 of file Model.h.

◆ v_J

std::vector<Math::SpatialVector> v_J

Definition at line 180 of file Model.h.

◆ X_base

std::vector<Math::SpatialTransform> X_base

Transformation from the base to bodies reference frame.

Definition at line 237 of file Model.h.

◆ X_lambda

std::vector<Math::SpatialTransform> X_lambda

Transformation from the parent body to the current body

$X_{\lambda(i)} = {}^{i} X_{\lambda(i)}$

.

Definition at line 235 of file Model.h.

◆ X_T

std::vector<Math::SpatialTransform> X_T

Transformations from the parent body to the frame of the joint.

Definition at line 187 of file Model.h.

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

include/rbdl/Model.h
src/Model.cc
src/Model_formatted.cc

Public Member Functions

Data Fields

Detailed Description

Constructor & Destructor Documentation

◆ Model()

Member Function Documentation

◆ AddBody()

◆ AddBodyCustomJoint()

◆ AddBodySphericalJoint()

◆ AppendBody()

◆ GetBodyId()

◆ GetBodyName()

◆ GetJointFrame()

◆ GetParentBodyId()

◆ GetQuaternion()

◆ IsBodyId()

◆ IsFixedBodyId()

◆ SetJointFrame()

◆ SetQuaternion()

Field Documentation

◆ a

◆ c

◆ c_J

◆ d

◆ dof_count

◆ f

◆ fixed_body_discriminator

◆ gravity

◆ hc

◆ hdotc

◆ I

◆ IA

◆ Ic

◆ lambda

◆ lambda_q

◆ mBodies

◆ mBodyNameMap

◆ mCustomJoints

◆ mFixedBodies

◆ mFixedJointCount

◆ mJoints

◆ mJointUpdateOrder

◆ mu

◆ multdof3_Dinv

◆ multdof3_S

◆ multdof3_U

◆ multdof3_u

◆ multdof3_w_index

◆ pA

◆ previously_added_body_id

◆ q_size

◆ qdot_size

◆ S

◆ U

◆ u

◆ v

◆ v_J

◆ X_base

◆ X_lambda

◆ X_T