ardupilot/libraries/AP_Math/quaternion.h

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/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// Copyright 2012 Andrew Tridgell, all rights reserved.
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// Refactored by Jonathan Challinger
#pragma once
#include <cmath>
#if MATH_CHECK_INDEXES
#include <assert.h>
#endif
#include <math.h>
class Quaternion {
public:
float q1, q2, q3, q4;
// constructor creates a quaternion equivalent
// to roll=0, pitch=0, yaw=0
Quaternion()
{
q1 = 1;
q2 = q3 = q4 = 0;
}
// setting constructor
Quaternion(const float _q1, const float _q2, const float _q3, const float _q4) :
q1(_q1), q2(_q2), q3(_q3), q4(_q4)
{
}
// setting constructor
Quaternion(const float _q[4]) :
q1(_q[0]), q2(_q[1]), q3(_q[2]), q4(_q[3])
{
}
// function call operator
void operator()(const float _q1, const float _q2, const float _q3, const float _q4)
{
q1 = _q1;
q2 = _q2;
q3 = _q3;
q4 = _q4;
}
// check if any elements are NAN
bool is_nan(void) const WARN_IF_UNUSED
{
return isnan(q1) || isnan(q2) || isnan(q3) || isnan(q4);
}
// return the rotation matrix equivalent for this quaternion
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void rotation_matrix(Matrix3f &m) const;
// return the rotation matrix equivalent for this quaternion after normalization
void rotation_matrix_norm(Matrix3f &m) const;
// return the rotation matrix equivalent for this quaternion
void from_rotation_matrix(const Matrix3f &m);
// create a quaternion from a given rotation
void from_rotation(enum Rotation rotation);
// rotate this quaternion by the given rotation
void rotate(enum Rotation rotation);
// convert a vector from earth to body frame
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void earth_to_body(Vector3f &v) const;
// create a quaternion from Euler angles
void from_euler(float roll, float pitch, float yaw);
// create a quaternion from Euler angles applied in yaw, roll, pitch order
// instead of the normal yaw, pitch, roll order
void from_vector312(float roll, float pitch, float yaw);
// convert this quaternion to a rotation vector where the direction of the vector represents
// the axis of rotation and the length of the vector represents the angle of rotation
void to_axis_angle(Vector3f &v) const;
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// create a quaternion from a rotation vector where the direction of the vector represents
// the axis of rotation and the length of the vector represents the angle of rotation
void from_axis_angle(Vector3f v);
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// create a quaternion from its axis-angle representation
// the axis vector must be length 1. the rotation angle theta is in radians
void from_axis_angle(const Vector3f &axis, float theta);
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// rotate by the provided rotation vector
void rotate(const Vector3f &v);
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// create a quaternion from a rotation vector
// only use with small angles. I.e. length of v should less than 0.17 radians (i.e. 10 degrees)
void from_axis_angle_fast(Vector3f v);
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// create a quaternion from its axis-angle representation
// the axis vector must be length 1, theta should less than 0.17 radians (i.e. 10 degrees)
void from_axis_angle_fast(const Vector3f &axis, float theta);
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// rotate by the provided rotation vector
// only use with small angles. I.e. length of v should less than 0.17 radians (i.e. 10 degrees)
void rotate_fast(const Vector3f &v);
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// get euler roll angle
float get_euler_roll() const;
// get euler pitch angle
float get_euler_pitch() const;
// get euler yaw angle
float get_euler_yaw() const;
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// create eulers from a quaternion
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void to_euler(float &roll, float &pitch, float &yaw) const;
// create eulers from a quaternion
Vector3f to_vector312(void) const;
float length(void) const;
void normalize();
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// initialise the quaternion to no rotation
void initialise()
{
q1 = 1.0f;
q2 = q3 = q4 = 0.0f;
}
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Quaternion inverse(void) const;
// reverse the rotation of this quaternion
void invert();
// allow a quaternion to be used as an array, 0 indexed
float & operator[](uint8_t i)
{
float *_v = &q1;
#if MATH_CHECK_INDEXES
assert(i < 4);
#endif
return _v[i];
}
const float & operator[](uint8_t i) const
{
const float *_v = &q1;
#if MATH_CHECK_INDEXES
assert(i < 4);
#endif
return _v[i];
}
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Quaternion operator*(const Quaternion &v) const;
Vector3f operator*(const Vector3f &v) const;
Quaternion &operator*=(const Quaternion &v);
Quaternion operator/(const Quaternion &v) const;
// angular difference between quaternions
Quaternion angular_difference(const Quaternion &v) const;
// absolute (e.g. always positive) earth-frame roll-pitch difference (in radians) between this Quaternion and another
float roll_pitch_difference(const Quaternion &v) const;
};