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OSCAR::IDLagrange Class Reference
[Dynamics]

Inverse dynamics using Lagrange. More...

#include <IDLagrange.h>

Inheritance diagram for OSCAR::IDLagrange:

[legend]List of all members.


Public Methods
	IDLagrange (unsigned int DOF, const String &linkCGandMassFile, const String &linkInertiaFile, const Vector3D &gravity=Vector3D(0.0, 0.0,-9.8))
	IDLagrange (unsigned int DOF, const MatrixData &linkCGandMass, const TensorData &linkInertia, const Vector3D &gravity=Vector3D(0.0, 0.0,-9.8))
virtual	~IDLagrange ()
bool	SetGfunctions (const Tensor tg, const Tensor rg=0)
bool	SetHfunctions (const TensorP th, const TensorP rh)
bool	GetGravityTorques (Vector &gravityTorques)
bool	GetVelocityTorques (const Vector &velocity, Vector &torques)
bool	GetAccelerationTorques (const Vector &acceleration, Vector &torques)
const Vector &	GetJointTorques (const Vector &velocity, const Vector &acceleration, const HandPose &eefLoad=HandPose(0, 0, 0, 0, 0, 0))
const Matrix *	GetInertiaMatrix ()
const Rot3by3 *	GetGlobalInertiaMatrices (const Xform *global_ts)
const Matrix *	GetIstar (const Xform *global_ts)
const Tensor *	GetIstarForEachLink (const Xform *global_ts)
const Tensor *	GetPstar ()
const Tensor *	GetPstar (const Xform *global_ts)
bool	GetAppliedLoadTorques (unsigned int linkNumber, const Tensor &gr, const Tensor &gt, const Vector &link_load, Vector &jnt_torques)
Protected Methods
void	fillRotationMatrices (const Xform *global_ts)
bool	calculateGlobalInertiaMatrices (const Xform *global_ts)
bool	calculateIstar ()
bool	calculateIstarForEachLink ()
bool	calculatePstar ()
Protected Attributes
Rot3by3 *	rotations
Rot3by3 *	rotations_trans
Tensor *	global_inertia
Matrix *	Istar
Tensor *	linkIstars
Tensor *	Pstar
const Tensor *	trans_g
const Tensor *	rot_g
const TensorP *	trans_h
const TensorP *	rot_h
bool	IstarUpdated
bool	PstarUpdated
bool	gravityUpdated
Private Methods
	IDLagrange (const IDLagrange &)
IDLagrange &	operator= (const IDLagrange &)

Detailed Description

Author:: Chaten Kapoor

Constructor & Destructor Documentation

OSCAR::IDLagrange::IDLagrange ( unsigned int DOF,

const String & linkCGandMassFile,

const String & linkInertiaFile,

const Vector3D & gravity = Vector3D(0.0, 0.0,-9.8)

)

Constructor.

Parameters:

dof Degrees of freedom (number of joints) of the robot.

linkCGandMassFile Name of file containing link center of gravity and mass data. The format of the data is as follows. The number of rows is equal to DOF. The number of columns is 4, with the first three indicating the center of gravity of the link in the local frame and the last one being the mass of that link. The following example is for a 2-D planar robot.

# This file contains centers of gravity and masses for a 2-DOF planar robot.

# X Y Z mass

0.2 0.0 0.0 5 # link 1

0.1 0.0 0.0 3 # link 2

Parameters:

linkInertiaFile Name of file containing link inertia data. The inertia of each link is represented as a 3X3 matrix called inertia tensor written in the frame at the center of gravity of the link. This frame is a local frame so it's fixed relative to the link. The elements of this 3X3 matrix are in the following form.

Ixx Ixy Ixz

Ixy Iyy Iyz

Ixz Iyz Izz

where Ixx, Iyy, and Izz are the mass moments of inertia and Ixy, Ixz, and Iyz are the mass products of inertia.
The number of 3X3 matrices equals to DOF. The following example is for a 2-D planar robot.
# This file contains the inertia tensors for a 2-DOF planar robot.

# Link 1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.001

# Link 2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.001

Parameters:

gravity Vector3D object of the gravity constant in the DH frame. Default is Vector3D(0,0,-9.8), which is the gravity constant in SI unit in the Z-direction which is usually the case for spatial robots. For planar robots, it is typically Vector3D(0,-9.8,0).

Exceptions:

dofAndMassDataMismatch dofAndMassDataMismatch

dofAndInertiaDataMismatch dofAndInertiaDataMismatch

OSCAR::IDLagrange::IDLagrange ( unsigned int DOF,

const MatrixData & linkCGandMass,

const TensorData & linkInertia,

const Vector3D & gravity = Vector3D(0.0, 0.0,-9.8)

)

Constructor.

Parameters:

DOF Degrees of freedom (number of joints) of the robot.

linkCGandMass MatrixData object containing link center of gravity and mass data. The number of rows is equal to DOF, each corresponding to each link. The number of columns is 4, with the first three indicating the center of gravity of the link and the last one being the mass of that link.

linkInertia TensorData object containing the link inertia data. The inertia of each link is represented as a 3X3 matrix. The number of 3X3 matrices equals to DOF.

gravity Vector3D object of the gravity constant in the DH frame. Default is Vector3D(0,0,-9.8), which is the gravity constant in SI unit in the Z-direction which is usually the case for spatial robots. For planar robots, it is typically Vector3D(0,-9.8,0).

Exceptions:

dofAndMassDataMismatch dofAndMassDataMismatch

dofAndInertiaDataMismatch dofAndInertiaDataMismatch

virtual OSCAR::IDLagrange::~IDLagrange ( ) [virtual]

OSCAR::IDLagrange::IDLagrange ( const IDLagrange & ) [private]

Member Function Documentation

bool OSCAR::IDLagrange::calculateGlobalInertiaMatrices ( const Xform * global_ts ) [protected]

bool OSCAR::IDLagrange::calculateIstar ( ) [protected]

bool OSCAR::IDLagrange::calculateIstarForEachLink ( ) [protected]

bool OSCAR::IDLagrange::calculatePstar ( ) [protected]

void OSCAR::IDLagrange::fillRotationMatrices ( const Xform * global_ts ) [protected]

bool OSCAR::IDLagrange::GetAccelerationTorques ( const Vector & acceleration,

Vector & torques

) [virtual]

A pure virtual function for calculating the joint torques due to acceleration.

Returns:
false if torques or acceleration is not of size DOF. Call GetError for more detailed error information. Otherwise, return true.

Parameters:

acceleration The vector of current joint accelerations.

torques Vector object of size DOF returning the acceleration torques.

Exceptions:

vectorSizeMismatch vectorSizeMismatch

Implements OSCAR::InverseDynamics.

bool OSCAR::IDLagrange::GetAppliedLoadTorques ( unsigned int linkNumber,

const Tensor & gr,

const Tensor & gt,

const Vector & link_load,

Vector & jnt_torques

)

const Rot3by3* OSCAR::IDLagrange::GetGlobalInertiaMatrices ( const Xform * global_ts )

bool OSCAR::IDLagrange::GetGravityTorques ( Vector & gravityTorques ) [virtual]

A pure virtual function for calculating the gravity torques.

Returns:
true if torques is of size DOF. If not, then false. Call GetError for more detailed error information.

Parameters:

gravityTorques Vector object of size DOF returning the gravity torques.

Exceptions:

vectorSizeMismatch vectorSizeMismatch

Implements OSCAR::InverseDynamics.

const Matrix* OSCAR::IDLagrange::GetInertiaMatrix ( ) [virtual]

A pure virtual function for calculating the inertia matrix.

Returns:
A pointer to a constant Matrix object containing the inertia matrix.

Implements OSCAR::InverseDynamics.

const Matrix* OSCAR::IDLagrange::GetIstar ( const Xform * global_ts )

A function for calculating the inertia matrix. Before this can be calculated the G functions must have been set by calling SetGfunctions. SetLinkPoints must be called in FKVelocity to move the G functions to the cgs before calling SetGfunctions.

Returns:
A pointer to a constant Matrix object containing the inertia matrix.

Parameters:

global_ts A pointer to a Xform object containing the global transformations. These global transformations are created in the FKVelocity object by calling GetAllGlobalTransformations.

const Tensor* OSCAR::IDLagrange::GetIstarForEachLink ( const Xform * global_ts )

const Vector& OSCAR::IDLagrange::GetJointTorques ( const Vector & velocity,

const Vector & acceleration,

const HandPose & eefLoad = HandPose(0, 0, 0, 0, 0, 0)

) [virtual]

A pure virtual function for calculating the total joint torques.

Returns:
an Vector object containing the joint torques.

Parameters:

velocity The vector of current joint velocities

acceleration The vector of current joint accelerations.

eefLoad The EEF load.

Exceptions:

vectorSizeMismatch vectorSizeMismatch

Implements OSCAR::InverseDynamics.

const Tensor* OSCAR::IDLagrange::GetPstar ( const Xform * global_ts )

const Tensor* OSCAR::IDLagrange::GetPstar ( )

bool OSCAR::IDLagrange::GetVelocityTorques ( const Vector & velocity,

Vector & torques

) [virtual]

A pure virtual function for calculating the joint torques due to velocity (Coriolis and centripetal effects).

Returns:
false if torques or velocity is not of size DOF. Call GetError for more detailed error information. Otherwise, return true.

Parameters:

velocity The vector of current joint velocities

torques Vector object of size DOF returning the velocity torques.

Exceptions:

vectorSizeMismatch vectorSizeMismatch

Implements OSCAR::InverseDynamics.

IDLagrange& OSCAR::IDLagrange::operator= ( const IDLagrange & ) [private]

bool OSCAR::IDLagrange::SetGfunctions ( const Tensor * tg,

const Tensor * rg = 0

)

MUST call this function before calling any GetXXX() method to set the G functions. The G functions must be at the centers of gravity for all links. These cgs are set by calling SetLinkPoints in the FKVelocity object.

Returns:
true if tg and rg are of correct sizes. If not, return false.

Parameters:

tg A pointer to a constant Tensor containing the translational G functions of the links.

rg A pointer to a constant Tensor containing the rotational G functions of the links. These G functions can be obtained using the FKVelocity class

bool OSCAR::IDLagrange::SetHfunctions ( const TensorP * th,

const TensorP * rh

)

MUST call this function before calling any GetAccelerationTorques() method to set the H functions. The H functions must be at the centers of gravity for all links. These cgs are set by calling SetLinkPoints in the FKVelocity object.

Returns:
true if th and rh are of correct sizes. If not, return false.

Parameters:

th A pointer to a constant Tensor containing the translational H functions of the links.

rh A pointer to a constant Tensor containing the rotational H functions of the links. These H functions can be obtained using the FKAcceleration class