Quaternion Class Reference

#include <Quaternion.h>

Public Member Functions
	Quaternion (float w_, float x_, float y_, float z_)
Quaternion	operator* (Quaternion qt)
Quaternion	operator*= (Quaternion qt)
Quaternion	normalize ()
Quaternion	conjugate ()
Vector3	rotate_vector (Vector3 vt)
Quaternion	from_axis_angle (float theta, Vector3 vt)
Vector3	quaternion_to_euler ()
Quaternion	euler_to_quaternion (Vector3 vt)
Quaternion	update_with_rates (float dt, Vector3 rates)
Quaternion	update_with_accel (Vector3 at, Vector3 target_vector, float gain)
Quaternion	update_with_mag (Vector3 mt, Vector3 at, Vector3 target_vector, Quaternion declination_compensation, float gain)

Public Attributes
float	w
float	x
float	y
float	z

Detailed Description

Class to perform quaternion math

w - x - y - z components

Input for euler angle and other orientation math: X Roll Y Pitch Z Yaw Euler rotation order: Z - Y - X

Member Function Documentation

conjugate()

Quaternion Quaternion::conjugate

(

)

Calculates conjugate of quaternion (backwards rotation)

Returns

Conjugate of this quaternion

euler_to_quaternion()

Quaternion Quaternion::euler_to_quaternion

(

Vector3

vt

)

Converts XYZ Euler angles to a quaternion representation (Z-Y-X Yaw-Pitch-Roll order)

Parameters

vt	Euler angles vector (Roll - Pitch - Yaw)

Returns

This quaternion after conversion

from_axis_angle()

Quaternion Quaternion::from_axis_angle	(	float	theta,
		Vector3	vt )

Sets quaternion from axis-angle representation

Parameters

theta	Angle component
vt	Vector component

Returns

This quaternion after conversion

normalize()

Quaternion Quaternion::normalize

(

)

Returns normalized quaternion (sets length to 1) if its magnitude is not zero

Returns

Normalized quaternion

operator*()

Quaternion Quaternion::operator*

(

Quaternion

qt

)

Quaternion product operator

Parameters

qt	Other quaternion to do the product with

Returns

This quaternion

operator*=()

Quaternion Quaternion::operator*=

(

Quaternion

qt

)

Quaternion product operator, updates the current quaternion

Parameters

qt	Other quaternion to do the product with

Returns

This quaternion

quaternion_to_euler()

Vector3 Quaternion::quaternion_to_euler

(

)

Calculates euler representation of quaternion rotation (Z-Y-X Yaw-Pitch-Roll)

Returns

Euler angles vector (Roll - Pitch - Yaw)

rotate_vector()

Vector3 Quaternion::rotate_vector

(

Vector3

vt

)

Returns Vector3 rotated by a quaternion

Parameters

vt	Vector3 to be rotated

Returns

vt after rotation

update_with_accel()

Quaternion Quaternion::update_with_accel	(	Vector3	at,
		Vector3	target_vector,
		float	gain )

Updates quaternion from inertial-frame accelerometer readings, (x = +1g | +9.8m/s^2). Algorithm works on the idea that the x axis (upwards) should have all the acceleration while y and z should be zero

Parameters

vt	Dimensionless inertial accelerometer measurements
target_vector	Vector to which the accelerometers should "point at"
gain	How much to rotate quaternion by (0 - 1.0f)

Returns

This quaternion after updating

update_with_mag()

Quaternion Quaternion::update_with_mag	(	Vector3	mt,
		Vector3	at,
		Vector3	target_vector,
		Quaternion	declination_compensation,
		float	gain )

Updates quaternion from body-frame magnetometer readings in the same manner the accelerometer update does

Parameters

mt	Dimensionless body magnetometer measurements
at	Dimensionless body accelerometer measurements
target_vector	Vector to which EAST should "point at"
gain	How much to rotate quaternion by (0 - 1.0f)

Returns

This quaternion after updating

update_with_rates()

Quaternion Quaternion::update_with_rates	(	float	dt,
		Vector3	rates )

Updates quaternion from body-axis angular rates

Parameters

rates	Radian angular rates
dt	Delta time

Returns

This quaternion after updating

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

• Quaternion.h
• Quaternion.cpp