[UAV] gyroscope data analysis, taking Victor intelligent jy901b as an example

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JY901B- Information details - Witt intelligence

Ten axis accelerometer gyroscope module attitude angle sensor inclination magnetometer air pressure altitude JY901B

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brief introduction

The data information that can be measured mainly includes the following parts ：

• Triaxial acceleration
• Three axis gyroscope
• Triaxial angle
• Triaxial magnetic field
• pressure + Height
• 200Hz Comes back

Information accuracy and output information mainly include ：

Angular accuracy ： dynamic $0.1°$ static state $0.05°$
Magnetic field accuracy ：$1mg$
Height accuracy ：$0.5$
Return rate ：$0.1Hz$ ～ $200Hz$ Adjustable
Output content ： The acceleration 、 gyroscope 、 Euler Angle 、 The magnetic field 、 Four yuan number 、 Time 、 Port status
range ： The acceleration ：$\pm 16g$, angular velocity ：$\pm 2000°/s$, angle ：$\pm 180°$

1 The acceleration Acceleration

The acceleration is the ratio of the change in velocity to the time taken for this change to occur $\Delta v/\Delta t$, It is a physical quantity that describes the speed change of an object , The common unit is $m/s^2$ （ rice / Square second ）.

2 gyroscope Gyroscope

Motion has six degrees of freedom ： Translate in three orthogonal directions and rotate around three orthogonal axes . The latter three are measured by angular velocity sensor , Also called gyroscope （gyroscope Or for short gyro）. The basic principle of gyroscope is Newton's second law , Like an acceleration sensor . If you add rotation to Newton's equation , There will be virtual forces , The mathematical term is Coriolis force . The working principle of gyroscope is to convert rotation into Coriolis force . The gyroscope requires a main motion or a feed motion , Coriolis force is the result of two orthogonal motions , And orthogonal to both .

3 Euler Angle Euler angles

【 control 】 Attitude angle analysis of four rotor UAV

Euler angle consists of three numbers , Each number represents the angle of rotation around a coordinate axis . Euler angle also has different ways of writing and expression .

The rotation order of Euler angle cannot be changed at will , Pay attention to the reference coordinate system when describing . Essentially because ： The linear transformation does not satisfy the commutative law of multiplication .

4 The magnetic field Magnetic

Gauss is short for high , yes CGS A unit of magnetic induction or flux in a system , In memory of the German mathematician Karl · Friedrich · Gauss , Common symbols $G$ or $Gs$ Express .

If it is placed in a magnetic field with uniform magnetic induction , A long straight wire with a direction perpendicular to the direction of magnetic induction intensity is in communication 1 Electromagnetic unit （emu） Steady current （ be equal to 10 Ampere ） when , The electromagnetic force on the conductor per centimeter of length is 1 Dyne , Then the magnetic induction intensity is defined as 1 gaussian .

The unit of magnetic induction in Gauss and SI units, Tesla （T） The conversion relationship is ：

• 1 G = 1×10-4 T＝0.1 mT
• 1 T = 10000 G

The intensity of the magnetic field on the equator of the earth's surface is about 0.29～0.40 gaussian , The magnetic field strength of the geomagnetic north pole is 0.61 gaussian , The magnetic field intensity of the geomagnetic south pole is 0.68 gaussian .

5 Four yuan number Quaternion

The unit is 4 yuan （Unit quaternion） It can be used to represent rotation in three-dimensional space . It is different from the other two commonly used expressions （ Three dimensional orthogonal matrix and Euler angle ） It is equivalent. , But it avoids the problem of universal lock in Euler angle representation . Compared with three-dimensional orthogonal matrix representation , Quaternion representation can more conveniently give the rotation axis and rotation angle .

6 Time

7 Port status

Supplementary knowledge

Ref：

1. About 3、6、9、10 The difference and definition of axis attitude gyroscope
2. gyroscope
3. Read gyroscope sensor ： Navigation 、 Drones and cars that never fall are inseparable from it ！- Know about columns
4. Data processing of gyroscope - Know about columns
5. Accelerometer 、 Working principle of gyroscope and data fusion
6. Back to the basics —— Understand geometric rotation and Euler angle
7. Can the rotation order of Euler angle be changed ？
8. How to explain Euler angle popularly ？ Then why introduce quaternions ？
9. The magnetic field
10. Three dimensional rotation representation - Euler angle 、 Rotation matrix 、 Rotation vector 、 Quaternion
11. How to understand quaternion vividly ？- Know about columns
12. Vision SLAM The foundation of mathematics in Second articles Four yuan number