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en:mag_subsys [2017/12/01 13:43]
writer
en:mag_subsys [2020/01/20 09:15]
golikov
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-**Magnetometer** \\  +====== ​Magnetometer ​======
-Virtual [[power_subsys|consumption]] - 40mA +
  
-{{ ru:device_standart.jpg?​direct&​200|}} +Virtual power draw40 mA
-Designing spacecrafts operating in low orbits a magnetometer is used as one of the devices for determining the orientation (usually added to solar sensors). The magnetometer measures magnetic field around itself and gives out three components of the magnetic field induction vector. Unit of measurement is Tesla. Under ideal conditions the magnetometer on board the satellite measures the geomagnetic field of the Earth - the thing that causes the compass needle to rotate on the ground user. However, in real life, the construction of any satellite contains magnetic materials (for example, permanent magnets of electric drives), so the magnetometer measures a certain total field of the Earth and the field of the satellite itself - the so-called superposition of fields.+
  
-The magnetic field of the Earth is well researched, and not only at the surface of the Earth but also in near-Earth space. Although there are some distinctions in its behavior and many not fully explored interesting effects... But this is science. To determine satellite orientation according to the magnetometer readings it is enough to use the accurate mathematical model of the magnetic field, for example IGRF, which can be laid on the satellite in the form of program code.\\ +{{ :ru:магнитометр.png?direct&200| Магнитометр}}
-{{ ::earth_mag_field.jpg?200|}} +
-Comparison of magnetometer readings with the calculated values according to the geomagnetic field model makes it possible to estimate the orientation (and in some cases the position) of the spacecraft in space. When carrying out experiments with a "​satellite"​ in the laboratory, it is proposed to use a magnetometer as an instrument both for determining the orientation and for determining the position of the satellite in "​orbit",​ i.e. for navigation. In this case special laboratory equipment creates the "​geomagnetic"​ field, measured by a magnetometer on board. It is controlled from the computer according to a predetermined control law.+
  
-At the beginning of the experiment, users will be given function ​of the magnetic field dependence on the satellite position on orbit above the planet. After that you should make appropriate changes in your program code to make it possible to determine the satellite position according to the magnetometer readings.+Low-orbit spacecraft is most often designed with magnetometer as one of positioning devices (usually complementing solar sensors).
  
-To obtain ​the current ​magnetometer ​readings use this function:\\  +The magnetometer senses the surrounding magnetic field and generates three components of the magnetic flux vector in teslas. In ideal conditions ​the magnetometer ​in the orbiter register’s Earth’s own geomagnetic field – the same field that turns the needle in the compass for a user on the ground. Howeverin the real life the design of any satellite includes magnetic materials (e.g. permanent magnets of electric drive motors), therefore the field registered by the magnetometer will comprise a so-called superposition of the Earth’s magnetic field and the magnetic field of the orbiter proper.
-  int32_t magnetometer_request_raw(uint16_t num,int16_t *pRAW_dataX,​int16_t *pRAW_dataY,​int16_t *pRAW_dataZ);  ​+
  
 +It is possible to determine the spatial orientation (and sometimes position as well) of spacecraft by comparing magnetometer readings with computed values from the geomagnetic field model. For experiments with the Orbicraft construction set it is assumed that the magnetometer will be used to sense both orientation and position of the satellite on the orbit i.e. for navigational purposes. In this case the “geomagnetic” field registered by the magnetometer onboard will be created by the special Terra laboratory setup and measured from the computer using a predetermined known control law.
 +
 +The following function (in C) is used to obtain current magnetometer readings:
 +
 +<code C>​int32_t magnetometer_request_raw(uint16_t num,int16_t *pRAW_dataX,​int16_t *pRAW_dataY,​int16_t *pRAW_dataZ);​ </​code> ​
 +
 +As would be the case with real-world spacecraft, magnetometer readings inside Orbicraft are not determined exclusively by the external geomagnetic field. Other instruments (mainly including reaction wheel motors and the power supply system) can interfere with readings. For that reason it is not recommended that the magnetometer be located immediately next to those devices.
  
-Once again, we emphasize that inside the "​satellite",​ as well as on real spacecrafts,​ the readings of magnetometer depend not only on the external "​geomagnetic"​ field. Other devices (mainly [[wheel_subsys|flywheel motors]] and [[power_subsys|power supply systems]]) can interfere with measurements,​ so it is not recommended to install a magnetometer near these devices. 
  
en/mag_subsys.txt · Last modified: 2020/03/25 16:28 (external edit)