Quaternion class for attitude representation. More...

#include <Quaternion.hpp>

Inheritance diagram for clockwerk::Quaternion< T >:

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Collaboration diagram for clockwerk::Quaternion< T >:

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Public Member Functions
	Quaternion ()
	Default constructor generates Quaternion sequence as zero rotation – 1 0 0 0.

	Quaternion (const T(&initial)[4])
	Constructor for Matrix class with initialization. Initializes matrix to values passed in via array.

	Quaternion (const Quaternion< T > &initial)
	Copy constructor for Quaternion class. Copies data from Quaternion object to the current instance.

	Quaternion (const std::array< T, 4 > &initial)
	Constructor for Matrix class with initialization. Initializes matrix to values passed in via array.

	~Quaternion ()
	Destructor – doesn't do anything because we don't dynamically allocate.

Quaternion< T > &	operator= (const Quaternion< T > &other)
	Equals operator overload for quaternion.

void	rate (const CartesianVector< T, 3 > &omega_f1_f2__f1, Matrix< T, 4, 1 > &quatdot_f1_f2) const
	Function to calculate the rate of change in the current representation based on the omega vector.

void	toDCM (DCM< T > &dcm_f1_f2) const
	Function to convert current attitude to DCM.

DCM< T >	toDCM () const

void	toMRP (MRP< T > &mrp_f1_f2) const
	Function to convert current attitude to MRP.

MRP< T >	toMRP () const

int	rotationAngle (double &val) const
	Calculate the rotation angle represented by the quaternion.

T &	operator[] (unsigned int idx)
	Function to return a vector value.

int	set (const unsigned int &idx, const T &value)
	Setter specific to the vector class.

int	set (const unsigned int &row, const unsigned int &col, const T &value)
	Function to set a single value in the matrix.

int	get (const unsigned int &idx, T &result) const
	Getter specific to the vector class.

T	get (const unsigned int &idx) const
	Getter specific to the vector class.

int	get (const unsigned int &row, const unsigned int &col, T &result) const
	Function to get a single value in the matrix.

T	get (const unsigned int &row, const unsigned int &col) const
	Function to get a single value in the matrix.

int	norm (T &result) const
	Function to take the norm of a vector.

T	norm () const
	Function to take the norm of a vector.

int	normSquared (T &result) const
	Function to take the squared norm of a vector.

T	normSquared () const
	Function to take the squared norm of a vector.

int	unit (CartesianVector< T, L > &result) const
	Function to return the unitized version of the vector.

int	unitize ()
	Function to unitize the current vector.

int	normalize ()
	Function to unitize the current vector.

std::string	str () const
	Function to write out vector as a string.

void	dump () const
	Function to dump information on matrix.

void	setFromArray (const T *start_ptr)
	Function to set the values of the matrix row-wise.

void	getAsArray (T *start_ptr) const
	Function to get the values of the matrix row-wise.

void	getCopy (Matrix< T, R, C > &result) const
	Function to get a copy of the matrix.

std::pair< unsigned int, unsigned int >	size ()
	Function to get the size of the matrix.

void	max (T &result, std::pair< unsigned int, unsigned int > &index) const
	Function to return the maximum value in the matrix.

void	min (T &result, std::pair< unsigned int, unsigned int > &index) const
	Function to return the minimum value in the matrix.

int	det (T &result) const
	Function to return the determinant of the matrix.

int	inverse (Matrix< T, R, C > &result) const
	Function to return the inverse of the matrix.

Matrix< T, R, C >	inverse () const

void	transpose (Matrix< T, C, R > &result) const
	Function to return the transpose of the matrix.

Matrix< T, C, R >	transpose () const

int	trace (T &result) const
	Function to return the trace of the matrix.

void	setToZeros ()
	Function to set all elements of the matrix to zero.

int	identity ()
	Function to set matrix to identity, if it is a square matrix.

int	eye ()

Public Attributes
std::array< std::array< T, C >, R >	values
	The actual values held by the matrix – a two dimensional array of values indexed as (row, column). NOTE: Public for ease of access and speed (no need to use setter/getter), and functions in Matrix and Safemath libraries are tested safe. Behavior using matrices outside of clockwerk libraries should use setter/getter, rather than direct access, for safety.

Protected Member Functions
int	_checkLookupBoundaries (const unsigned int &start_r, const unsigned int &end_r, const unsigned int &start_c, const unsigned int &end_c) const
	Function to check, given a set of submatrix boundaries, that those boundaries are valid for the current matrix.

int	_LUPDecompose (T *A[R], unsigned int P[R+1]) const
	Function to take a 2-d matrix represented by A and decompose it into LU form.

Detailed Description

template<typename T>
class clockwerk::Quaternion< T >

Quaternion class for attitude representation.

This file defines a simple Quaternion attitude representation for cartesian coordinate systems. It is largely the same as the base vector, with the following exceptions:

Set to be 4 elements
Functions defined to convert to other attitude representations
Function defined to calculate rate of change as a function of omega

Naming conventions

All naming conventions and equations are per Analytical Mechanics of Space Systems by Schaub and Junkins
The omega vector is sometimes denoted by w and assumed frame consistent with the attitude representation. For example, if a DCM represents the relative orientation between two frames [BN] the omega vector is assumed to be w_(B/N)
The naming convention for all vectors is: variablename_obj1_obj2__frameN (note the double underscore preceding frame) and reads back as: "variable variablename representing the relationship between obj1 and obj2 represented in frameN"
Unless otherwise noted angles are in RADIANS

NOTE: All attitude representations, including DCMs, are assumed to represent a three dimensional, cartesian coordinate system because that is what they are used, and in many cases defined, for.

Member Function Documentation

◆ _LUPDecompose()

int clockwerk::Matrix< T, R, C >::_LUPDecompose	(	T *	A[R],
		unsigned int	P[R+1]
	)		const

protectedinherited

Function to take a 2-d matrix represented by A and decompose it into LU form.

Parameters

A	A 2-d matrix represented as a double pointer After ops A contains a copy of both matrices L-E and U as A=(L-E)+U such that PA=LU.
P	The permutation matrix to hold info on matrix changes

Returns: Error code corresponding to codes in clockwerkerrors.h

Note: Code borrowed/updated from sample C code on wikipedia here: https://en.wikipedia.org/wiki/LU_decomposition

◆ det()

int clockwerk::Matrix< T, R, C >::det ( T & result ) const

inherited

Function to return the determinant of the matrix.

Operations to return important matrix information

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ get() [1/4]

T clockwerk::CartesianVector< T, L >::get ( const unsigned int & idx ) const

inlineinherited

Getter specific to the vector class.

Parameters

idx	The index to return

Returns: Value at index

Note: Does not bounds check index and should be treated safely

◆ get() [2/4]

int clockwerk::CartesianVector< T, L >::get	(	const unsigned int &	idx,
		T &	result
	)		const

inlineinherited

Getter specific to the vector class.

Parameters

idx	The index to return
value	PBR return of the value in the vector

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ get() [3/4]

T clockwerk::Matrix< T, R, C >::get	(	const unsigned int &	row,
		const unsigned int &	col
	)		const

inherited

Function to get a single value in the matrix.

Parameters

row	The row index
col	The column index

Returns: Matrix value at index

Note: Does not bounds check and is unsafe for embedded operations

◆ get() [4/4]

int clockwerk::Matrix< T, R, C >::get	(	const unsigned int &	row,
		const unsigned int &	col,
		T &	result
	)		const

inherited

Function to get a single value in the matrix.

Parameters

row	The row index
col	The column index
value	PBR return of the value in the matrix

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ getAsArray()

void clockwerk::Matrix< T, R, C >::getAsArray ( T * start_ptr ) const

inherited

Function to get the values of the matrix row-wise.

Parameters

start_ptr The data address at which write should begin.

Note: start_ptr must represent an array or similar type of at least R*C values; Not protected. May segfault if not used properly; The matrix [1 2; 3 4] would output as an array [1 2 3 4]

◆ getCopy()

void clockwerk::Matrix< T, R, C >::getCopy ( Matrix< T, R, C > & result ) const

inherited

Function to get a copy of the matrix.

Parameters

result PBR return of a copy of this matrix

◆ identity()

int clockwerk::Matrix< T, R, C >::identity ( )

inherited

Function to set matrix to identity, if it is a square matrix.

Returns: Error code corresponding to success/failure

◆ inverse()

int clockwerk::Matrix< T, R, C >::inverse ( Matrix< T, R, C > & result ) const

inherited

Function to return the inverse of the matrix.

Parameters

result PBR return of matrix inverse

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ max()

void clockwerk::Matrix< T, R, C >::max	(	T &	result,
		std::pair< unsigned int, unsigned int > &	index
	)		const

inherited

Function to return the maximum value in the matrix.

Parameters

result PBR return of maximum value

◆ min()

void clockwerk::Matrix< T, R, C >::min	(	T &	result,
		std::pair< unsigned int, unsigned int > &	index
	)		const

inherited

Function to return the minimum value in the matrix.

Parameters

result PBR return of minimum value

◆ norm() [1/2]

T clockwerk::CartesianVector< T, L >::norm ( ) const

inlineinherited

Function to take the norm of a vector.

Returns: return of the norm operation

◆ norm() [2/2]

int clockwerk::CartesianVector< T, L >::norm ( T & result ) const

inherited

Function to take the norm of a vector.

Parameters

result PBR return of the norm operation

◆ normalize()

int clockwerk::CartesianVector< T, L >::normalize ( )

inherited

Function to unitize the current vector.

Returns: Error code corresponding to those in clockwerkerrors.h

◆ normSquared() [1/2]

T clockwerk::CartesianVector< T, L >::normSquared ( ) const

inlineinherited

Function to take the squared norm of a vector.

Returns: return of the norm squared operation

◆ normSquared() [2/2]

int clockwerk::CartesianVector< T, L >::normSquared ( T & result ) const

inherited

Function to take the squared norm of a vector.

Parameters

result PBR return of the norm^2 operation

◆ operator[]()

T & clockwerk::CartesianVector< T, L >::operator[] ( unsigned int idx )

inherited

Function to return a vector value.

Parameters

idx	The index to return

Returns: Reference to the vector element

Note: This vector, much like std::array, does not check index range and should be used accordingly

◆ rate()

template<typename T >

void clockwerk::Quaternion< T >::rate	(	const CartesianVector< T, 3 > &	omega_f1_f2__f1,
		Matrix< T, 4, 1 > &	quatdot_f1_f2
	)		const

Function to calculate the rate of change in the current representation based on the omega vector.

Dynamics and kinematics functions

Parameters

omega_f1_f2__f1	Angular velocity vector for the attitude representation - omega of frame 1 wrt frame 2 expressed in frame 1
quatdot_f1_f2	Rate of change in the current Quaternion

◆ rotationAngle()

template<typename T >

int clockwerk::Quaternion< T >::rotationAngle ( double & val ) const

Calculate the rotation angle represented by the quaternion.

Parameters

val	Implicit return of rotation angle

Returns: Error code corresponding to success/failure

◆ set() [1/2]

int clockwerk::CartesianVector< T, L >::set	(	const unsigned int &	idx,
		const T &	value
	)

inlineinherited

Setter specific to the vector class.

Parameters

idx	Vector element to set
value	The value to set the element to

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ set() [2/2]

int clockwerk::Matrix< T, R, C >::set	(	const unsigned int &	row,
		const unsigned int &	col,
		const T &	value
	)

inherited

Function to set a single value in the matrix.

Getters and setters

Parameters

row	The row index
col	The column index
value	The value to set the matrix to

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ setFromArray()

void clockwerk::Matrix< T, R, C >::setFromArray ( const T * start_ptr )

inherited

Function to set the values of the matrix row-wise.

Parameters

start_ptr The data address at which read should begin.

Note: start_ptr must represent an array or similar type of at least R*C values; Not protected. May segfault if not used properly; The array [1 2 3 4] would read into a matrix as [1 2; 3 4]

◆ size()

std::pair< unsigned int, unsigned int > clockwerk::Matrix< T, R, C >::size ( )

inlineinherited

Function to get the size of the matrix.

Operations to get matrix info

◆ str()

std::string clockwerk::CartesianVector< T, L >::str ( ) const

inherited

Function to write out vector as a string.

Returns: Vector written as a square brace enclosed string

◆ toDCM()

template<typename T >

void clockwerk::Quaternion< T >::toDCM ( DCM< T > & dcm_f1_f2 ) const

Function to convert current attitude to DCM.

Conversions to other attitude representations

Parameters

PBR	return of DCM in PBR case

Returns: Integer error code corresponding to errors in clockwerkerrors.h

◆ toMRP()

template<typename T >

void clockwerk::Quaternion< T >::toMRP ( MRP< T > & mrp_f1_f2 ) const

Function to convert current attitude to MRP.

Parameters

PBR	return of MRP in PBR case

Returns: Integer error code corresponding to errors in clockwerkerrors.h

◆ trace()

int clockwerk::Matrix< T, R, C >::trace ( T & result ) const

inherited

Function to return the trace of the matrix.

Parameters

result PBR return of matrix trace

Returns: Integer value corresponding to error codes in clockwerkerrrors.h

◆ transpose()

void clockwerk::Matrix< T, R, C >::transpose ( Matrix< T, C, R > & result ) const

inherited

Function to return the transpose of the matrix.

Parameters

result PBR return of matrix transpose

Note: Overloaded for return as well

◆ unit()

int clockwerk::CartesianVector< T, L >::unit ( CartesianVector< T, L > & result ) const

inherited

Function to return the unitized version of the vector.

Parameters

result PBR return of the unit vector

Returns: Error code corresponding to those in clockwerkerrors.h

◆ unitize()

int clockwerk::CartesianVector< T, L >::unitize ( )

inherited

Function to unitize the current vector.

Returns: Error code corresponding to those in clockwerkerrors.h

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

/home/mickey/modelspace/clockwerk/src/six_dof_dynamics/DCM.hpp
/home/mickey/modelspace/clockwerk/src/six_dof_dynamics/Quaternion.hpp

Public Member Functions

Public Attributes

Protected Member Functions

Detailed Description

Naming conventions

Member Function Documentation

◆ _LUPDecompose()

◆ det()

Operations to return important matrix information

◆ get() [1/4]

◆ get() [2/4]

◆ get() [3/4]

◆ get() [4/4]

◆ getAsArray()

◆ getCopy()

◆ identity()

◆ inverse()

◆ max()

◆ min()

◆ norm() [1/2]

◆ norm() [2/2]

◆ normalize()

◆ normSquared() [1/2]

◆ normSquared() [2/2]

◆ operator[]()

◆ rate()

Dynamics and kinematics functions

◆ rotationAngle()

◆ set() [1/2]

◆ set() [2/2]

Getters and setters

◆ setFromArray()

◆ size()

Operations to get matrix info

◆ str()

◆ toDCM()

Conversions to other attitude representations

◆ toMRP()

◆ trace()

◆ transpose()

◆ unit()

◆ unitize()