The role of the electronic compass
An electronic compass is also called a digital compass. It is a method of using the geomagnetic field to determine the north pole. In fact, it is an electronic compass. Now electronic compasses are generally processed by magnetoresistive sensors and fluxgates.
Although GPS has a wide range of applications in navigation, positioning, speed measurement, and orientation, its signal is often blocked by terrain and ground objects, which greatly reduces the accuracy and even cannot be used. Especially in high-rise urban areas and densely-vegetated forest areas, the effectiveness of GPS signals is only 60%. And in the case of stationary, GPS can not give heading information. To make up for this shortcoming, a combined navigation and orientation method can be used. Electronic compass products are designed to meet users' such needs. It can effectively compensate the GPS signal to ensure that the navigation and orientation information is 100% effective, and it can work normally even after the GPS signal is out of lock, so that the star will not be lost.
Electronic compass can be divided into flat electronic compass and three-dimensional electronic compass. The flat electronic compass requires the user to keep the compass level when using it, otherwise, when the compass is tilted, it will also give a change in heading, but the actual heading does not change. Although the flat electronic compass is very demanding when used, if the carrier attached to the compass can be guaranteed to be always level, the flat compass is a very cost-effective choice. The three-dimensional electronic compass overcomes the strict limitations of the flat electronic compass in use, because the three-dimensional electronic compass has an inclination sensor inside it. If the compass is tilted, the compass can be compensated for tilt, so that even if the compass is tilted, the heading data is still accurate. . Sometimes in order to overcome temperature drift, the compass can also have built-in temperature compensation to minimize the temperature drift of the tilt angle and the pointing angle.
The three-dimensional electronic compass is composed of a three-dimensional magnetoresistive sensor, a dual-axis inclination sensor and an MCU. The three-dimensional magnetoresistive sensor is used to measure the earth's magnetic field, and the tilt sensor is compensated when the magnetometer is not in a horizontal state; the MCU processes the signal and data output of the magnetometer and the tilt sensor, as well as soft iron and hard iron compensation. The magnetometer uses three magnetoresistive sensors perpendicular to each other, and the sensor in each axis detects the intensity of the earth's magnetic field in that direction. The forward direction is called the x-direction sensor to detect the vector value of the earth’s magnetic field in the x direction; the right or Y-direction sensor detects the vector value of the earth’s magnetic field in the Y direction; the downward or Z-direction sensor detects the earth’s magnetic field in the Z direction The vector value of. The sensitivity of the sensor in each direction has been adjusted to the optimal point according to the partial vector of the geomagnetic field in that direction, and has a very low horizontal axis sensitivity. The analog output signal generated by the sensor is amplified and sent to the MCU for processing. The magnetic field measurement range is ±2 Gauss. By adopting a 12-bit A/D converter, the magnetometer can distinguish less than 1mGauss of magnetic field changes, and we can accurately measure the magnetic field strength of 200-300mGauss in the X and Y directions through this high resolution, regardless of whether it is at the equator. The upward change is still at the lower position of the north and south poles.
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