Six axis sensor use learning record

The six axes contain accelerometers and gyroscopes , Output three-axis acceleration and three-axis angular velocity , If it is nine axis, the magnetometer also outputs the relevant data of the earth's magnetic field, which is used to calculate the current exact Euler angle of the equipment to obtain the attitude of the equipment , Otherwise, you can only get the relative rotation angle

QMI8658

https://blog.csdn.net/weixin_43924988/article/details/124056069

Read carefully QMI8658 Six axis data and real acceleration 、 Conversion between angular velocity data

Euler Angle 、 Attitude angle 、 Four yuan number 、 Transformation matrix

1) Attitude angle pitch yaw roll

https://blog.csdn.net/yuzhongchun/article/details/22749521

2) Euler angle and attitude angle

Attitude angle ： It refers to the angle between the body coordinate system and the geographical coordinate system .
Euler Angle ： The angle of rotation around the three axes of the body coordinate system .
Relationship ： The Euler angle around a certain rotation order is equal to the attitude angle .
（1） stay NED( Northeast land ) Coordinate system （ Geographic coordinate system ） And the front lower right coordinate system （ Body coordinate system ） The definition of , Only press ZYX The Euler angle of sequential rotation is the attitude angle , Press yaw - pitch - roll (3-2-1) Rotation order of . Therefore, the rotation matrix from geographical coordinate system to body coordinate system is ：R(roll)*R(pitch)*R(yaw)（R(x)*R(y)*R(z)）.
（2） In the Northeast celestial coordinate system （ Geographic coordinate system ） And the upper right front coordinate system （ Body coordinate system ） The definition of , Only press ZXY The Euler angle of sequential rotation is the attitude angle , Press 3-1-2 Rotation order of . Therefore, the rotation matrix from geographical coordinate system to body coordinate system is ：R(y)*R(x)*R(z).
Others, such as the rotation matrix of the airflow coordinate system and the body coordinate system, can be obtained similarly .
** summary ：** The definition of coordinate system is matched with the rotation matrix , Do not mix ！

3) Four yuan number

Explain the definition of four elements , Each quantity and rotation angle 、 Calculation formula between rotation vectors , namely

 

When doing coordinate transformation in this way , Easy to calculate and correct 3 The result of the quaternion calculation is also a ternary ,q conjugate coordinate q

https://www.zhihu.com/question/23005815/answer/33971127

4) Relationship between quaternion and Euler angle 、 transformation

transformation

Understand and sort out ：1. Coordinate transformation matrix of Euler angle ：

 

               2. Coordinate transformation matrix of quaternion

                3. Quaternion and Euler angle

Refer to Wikipedia [2] The idea of , Euler angles construct quaternions , It is the same as the rotation matrix constructed by Euler angle , That is to rotate the three foundations Elemental Rotation Put together , Reference resources wiki

example, Example Sensor , Code ?