Compass gadget use and calibration
Immediately after
installing the BlessTags application, you will notice that the compass
application does not work properly.
Mainly, the purpose of compass calibration is to figure out how to compensate for the influence of the internal components and from internal magnetic fields generated by the SensorTag. Screws, metallic elements, speaker magnets, etc. interfere with the measured magnetic field. But more, the magnetic fields are also produced by the current flowing through wires.
The calibration process is based on the fact that the system can separate the internal and external contributions to the magnetic field by looking at how the magnetic field changes as the SensorTag is rotated. For example, in one orientation of the SensorTag the magnetic field from the speaker magnet will add on to the Earth's field; but when the SensorTag is oriented in the opposite direction, the two fields will partially cancel out.
The idea, behind the calibration process, is to record how the magnitude of the measured field changes and uses this to calibrate the x, y, and z magnetic field sensors placed inside the compass.
This is a perfect example to highlight the need for calibration of the magnetic sensor – placed on CC2650STK or CC2541DK SensorTags. In the following, a sensor calibration process is presented in a movie.
In a future post, I will present the mathematical basis of the magnetic sensor calibration and the software implementation mode.
Mainly, the purpose of compass calibration is to figure out how to compensate for the influence of the internal components and from internal magnetic fields generated by the SensorTag. Screws, metallic elements, speaker magnets, etc. interfere with the measured magnetic field. But more, the magnetic fields are also produced by the current flowing through wires.
The calibration process is based on the fact that the system can separate the internal and external contributions to the magnetic field by looking at how the magnetic field changes as the SensorTag is rotated. For example, in one orientation of the SensorTag the magnetic field from the speaker magnet will add on to the Earth's field; but when the SensorTag is oriented in the opposite direction, the two fields will partially cancel out.
The idea, behind the calibration process, is to record how the magnitude of the measured field changes and uses this to calibrate the x, y, and z magnetic field sensors placed inside the compass.
This is a perfect example to highlight the need for calibration of the magnetic sensor – placed on CC2650STK or CC2541DK SensorTags. In the following, a sensor calibration process is presented in a movie.
In a future post, I will present the mathematical basis of the magnetic sensor calibration and the software implementation mode.
If You Appreciate What I Do Here, You Should Consider:
Download BlessTags from Win. Store: http://www.microsoft.com/en-us/p/blesstags/9p054xsjjr1n
Download BlessTags Lite (the free version): http://www.microsoft.com/store/apps/9mt2kgztfjf5
Facebook: http://www.facebook.com/blessTags
Twitter: https://twitter.com/blesstags
Instagram: www.instagram.com/blesstags/
Or subscribe to Bluetooth low energy SensorTag by Email
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