This class stores a bodies mass, center of mass, and inertia information. The inertia elements are stored individually since the inertia matrix is a 3x3 symmetric matrix. The bodies inertia matrix, expressed about its center of mass, can be reconstructed as

$I_c = \begin{bmatrix} I_xx & I_yx & I_zx \\ I_yx & I_yy & I_zy \\ I_zx & I_zy & I_zz \end{bmatrix}$

The full RigidBodyInertia matrix has the following structure,

$\begin{bmatrix} I_c + (h\times)h & h\times \\ -h\times & \mathbf{1}_{3\times3}m \end{bmatrix}$

where $\mathbf{1}_{3\times 3}$ is a 3x3 identity matrix. More...

#include <RigidBodyInertia.hpp>

Inheritance diagram for RobotDynamics::Math::RigidBodyInertia:

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Public Member Functions
void	createFromMatrix (const SpatialMatrix &Ic)
	Create a Math::RigidBodyInertia object from a 6x6 Math::SpatialMatrix. More...

Matrix63	multiplyMatrix63 (Matrix63 m) const
	A helper method that returns a 6x3 matrix that is a Math::RigidBodyInertia multiplied by a 6x3 matrix. More...

void	operator+= (const RigidBodyInertia &rbi)
	Overloaded plus-equals operator. Adds two inertia matrices. More...

RigidBodyInertia &	operator= (const RigidBodyInertia &other)

	RigidBodyInertia ()
	Constructor. More...

	RigidBodyInertia (double mass, const Vector3d &com_mass, const Matrix3d &inertia)
	Constructor. More...

	RigidBodyInertia (double m, const Vector3d &h, const double Ixx, const double Iyx, const double Iyy, const double Izx, const double Izy, const double Izz)
	Constructor. More...

	RigidBodyInertia (const RigidBodyInertia &inertia)
	Copy constructor. More...

void	set (const RigidBodyInertia &I)
	Setter. More...

void	set (double m, const Vector3d &h, const double Ixx, const double Iyx, const double Iyy, const double Izx, const double Izy, const double Izz)
	Setter. More...

void	setSpatialMatrix (SpatialMatrix &mat) const
	Store a Math::RigidBodyInertia in the Math::SpatialMatrix. More...

SpatialMatrix	subtractSpatialMatrix (const SpatialMatrix &m) const
	Given Math::RigidBodyInertia ad Math::SpatialMatrix , returns Math::SpatialMatrix such that . More...

SpatialVector	timesSpatialVector (const SpatialVector &v) const
	Multiply a Math::RigidBodyInertia by a Math::SpatialVector and return the result as a new Math::SpatialVector. More...

SpatialMatrix	toMatrix () const

void	transform (const SpatialTransform &X)
	Transform a Math::RigidBodyInertia matrix. More...

RigidBodyInertia	transform_copy (const SpatialTransform &X) const
	Copy, transform, and return a Math::RigidBodyInertia. More...

Public Attributes
Vector3d	h

double	Ixx

double	Iyx

double	Iyy

double	Izx

double	Izy

double	Izz

double	m

Detailed Description

This class stores a bodies mass, center of mass, and inertia information. The inertia elements are stored individually since the inertia matrix is a 3x3 symmetric matrix. The bodies inertia matrix, expressed about its center of mass, can be reconstructed as

$I_c = \begin{bmatrix} I_xx & I_yx & I_zx \\ I_yx & I_yy & I_zy \\ I_zx & I_zy & I_zz \end{bmatrix}$

The full RigidBodyInertia matrix has the following structure,

$\begin{bmatrix} I_c + (h\times)h & h\times \\ -h\times & \mathbf{1}_{3\times3}m \end{bmatrix}$

where $\mathbf{1}_{3\times 3}$ is a 3x3 identity matrix.

Definition at line 45 of file RigidBodyInertia.hpp.

Constructor & Destructor Documentation

RobotDynamics::Math::RigidBodyInertia::RigidBodyInertia ( )

inline

Constructor.

Definition at line 51 of file RigidBodyInertia.hpp.

RobotDynamics::Math::RigidBodyInertia::RigidBodyInertia	(	double	mass,
		const Vector3d &	com_mass,
		const Matrix3d &	inertia
	)

inline

Constructor.

Parameters

mass	Body mass
com_mass	Vector pointing to center of mass scaled by the body mass
inertia	3x3 Inertia tensor about the bodies center of mass

Definition at line 61 of file RigidBodyInertia.hpp.

RobotDynamics::Math::RigidBodyInertia::RigidBodyInertia	(	double	m,
		const Vector3d &	h,
		const double	Ixx,
		const double	Iyx,
		const double	Iyy,
		const double	Izx,
		const double	Izy,
		const double	Izz
	)

inline

Constructor.

Parameters

m	Body mass
h	Vector pointing to center of mass scaled by the body mass
Ixx
Iyx
Iyy
Izx
Izy
Izz

Definition at line 77 of file RigidBodyInertia.hpp.

RobotDynamics::Math::RigidBodyInertia::RigidBodyInertia ( const RigidBodyInertia & inertia )

inline

Copy constructor.

Parameters

inertia

Definition at line 86 of file RigidBodyInertia.hpp.

Member Function Documentation

void RobotDynamics::Math::RigidBodyInertia::createFromMatrix ( const SpatialMatrix & Ic )

Create a Math::RigidBodyInertia object from a 6x6 Math::SpatialMatrix.

Parameters

Ic

Definition at line 90 of file RigidBodyInertia.cpp.

Matrix63 RobotDynamics::Math::RigidBodyInertia::multiplyMatrix63 ( Matrix63 m ) const

inline

A helper method that returns a 6x3 matrix that is a Math::RigidBodyInertia multiplied by a 6x3 matrix.

Parameters

m

Returns: The result of multiplying a Math::RigidBodyInertia by a 6x3 matrix

Definition at line 199 of file RigidBodyInertia.hpp.

void RobotDynamics::Math::RigidBodyInertia::operator+= ( const RigidBodyInertia & rbi )

Overloaded plus-equals operator. Adds two inertia matrices.

Parameters

rbi

Definition at line 14 of file RigidBodyInertia.cpp.

RigidBodyInertia& RobotDynamics::Math::RigidBodyInertia::operator= ( const RigidBodyInertia & other )

inline

Definition at line 207 of file RigidBodyInertia.hpp.

void RobotDynamics::Math::RigidBodyInertia::set ( const RigidBodyInertia & I )

inline

Setter.

Parameters

I

Definition at line 95 of file RigidBodyInertia.hpp.

void RobotDynamics::Math::RigidBodyInertia::set	(	double	m,
		const Vector3d &	h,
		const double	Ixx,
		const double	Iyx,
		const double	Iyy,
		const double	Izx,
		const double	Izy,
		const double	Izz
	)

inline

Setter.

Parameters

m	Body mass
h	Vector pointing to center of mass scaled by the body mass
Ixx
Iyx
Iyy
Izx
Izy
Izz

Definition at line 111 of file RigidBodyInertia.hpp.

void RobotDynamics::Math::RigidBodyInertia::setSpatialMatrix ( SpatialMatrix & mat ) const

Store a Math::RigidBodyInertia in the Math::SpatialMatrix.

Parameters

mat	Modified to store a Math::RigidBodyInertia in the Math::SpatialMatrix

Definition at line 122 of file RigidBodyInertia.cpp.

SpatialMatrix RobotDynamics::Math::RigidBodyInertia::subtractSpatialMatrix ( const SpatialMatrix & m ) const

inline

Given Math::RigidBodyInertia $ I_r $ ad Math::SpatialMatrix $ M_I $ , returns Math::SpatialMatrix $ M_r $ such that $ M_r = I_r - M_I $ .

Parameters

m

Returns: New Math::SpatialMatrix that is the Math::SpatialMatrix subtracted from a Math::RigidBodyInertia

Definition at line 173 of file RigidBodyInertia.hpp.

SpatialVector RobotDynamics::Math::RigidBodyInertia::timesSpatialVector ( const SpatialVector & v ) const

inline

Multiply a Math::RigidBodyInertia by a Math::SpatialVector and return the result as a new Math::SpatialVector.

Parameters

v

Returns: The result of a Math::RigidBodyInertia multiplied by a Math::SpatialVector

Definition at line 187 of file RigidBodyInertia.hpp.

SpatialMatrix RobotDynamics::Math::RigidBodyInertia::toMatrix ( ) const

Get a Math::RigidBodyInertia as a 6x6 Math::SpatialMatrix

Returns: A 6x6 matrix representing a Math::SpatialInertia matrix

Definition at line 102 of file RigidBodyInertia.cpp.

void RobotDynamics::Math::RigidBodyInertia::transform ( const SpatialTransform & X )

virtual

Transform a Math::RigidBodyInertia matrix.

Parameters

X

Implements RobotDynamics::Math::TransformableGeometricObject.

Definition at line 26 of file RigidBodyInertia.cpp.

RigidBodyInertia RobotDynamics::Math::RigidBodyInertia::transform_copy ( const SpatialTransform & X ) const

inline

Copy, transform, and return a Math::RigidBodyInertia.

Parameters

X

Returns: Returns a copied and transformed Math::RigidBodyInertia

Definition at line 141 of file RigidBodyInertia.hpp.

Member Data Documentation

Vector3d RobotDynamics::Math::RigidBodyInertia::h

Vector pointing to body center of mass in body frame, scaled by body mass

Definition at line 222 of file RigidBodyInertia.hpp.

double RobotDynamics::Math::RigidBodyInertia::Ixx