Gazebo Math

API Reference

6.15.1
Rotation example

This example explains how to use quaternions and euler angles, and how to convert between them.

Compiling and running the code

Go to ign-math/examples and use cmake to compile the code:

git clone https://github.com/ignitionrobotics/ign-math/ -b ign-math6
cd ign-math/examples
mkdir build
cd build
cmake ..
make

When the code is compiled, you can run two different examples, one which converts from quaternion to euler angles:

Usage:
./quaternion_to_euler <float_w> <float_x> <float_y> <float_z>
Example
./quaternion_to_euler 0.5 0.5 0.5 0.5

And the other which converts from euler to quaternion:

Usage (angles specified in radians):
quaternion_from_euler <float_roll> <float_pitch> <float_yaw>
Example
quaternion_from_euler 0 0 1.57

The ouput of each program, respectively:

./quaternion_to_euler 0.5 0.5 0.5 0.5
Normalizing Quaternion components:
W 0.5
X 0.5
Y 0.5
Z 0.5
to
W 0.5
X 0.5
Y 0.5
Z 0.5
Converting to Euler angles
roll 1.570796 radians
pitch -0.000000 radians
yaw 1.570796 radians
roll 90.000000 degrees
pitch -0.000000 degrees
yaw 90.000000 degrees
to Rotation matrix
0.000000 0.000000 1.000000
1.000000 0.000000 0.000000
0.000000 1.000000 0.000000
./quaternion_from_euler 0 0 1.57
Converting Euler angles:
roll 0.000000 radians
pitch 0.000000 radians
yaw 1.570000 radians
roll 0.000000 degrees
pitch 0.000000 degrees
yaw 89.954374 degrees
to Quaternion
W 0.707388
X 0.000000
Y 0.000000
Z 0.706825
to Rotation matrix
0.000796 -1.000000 0.000000
1.000000 0.000796 0.000000
0.000000 0.000000 1.000000

Code

You can create some objects to express rotations:

gz::math::Quaterniond q(roll, pitch, yaw);
gz::math::Vector3d euler(q.Euler());

To access the quaterions attributes:

printf(" W % .6f\n X % .6f\n Y % .6f\n Z % .6f\n",
q.W(), q.X(), q.Y(), q.Z());

Or to acccess the rotation matrix elements:

std::cout << "\nto Rotation matrix\n";
printf(" % .6f % .6f % .6f\n"
" % .6f % .6f % .6f\n"
" % .6f % .6f % .6f\n",
m(0, 0), m(0, 1), m(0, 2),
m(1, 0), m(1, 1), m(1, 2),
m(2, 0), m(2, 1), m(2, 2));
Matrix3< double > Matrix3d
Definition: gz/math/Matrix3.hh:548
Quaternion< double > Quaterniond
Definition: gz/math/Quaternion.hh:1101
T printf(T... args)
Vector3< double > Vector3d
Definition: gz/math/Vector3.hh:770