Electronic Compass and Gyroscope

MEMS gyroscopes are not the earliest motion sensors used in consumer electronics. Acceleration sensors and electronic compasses entered the consumer electronics market earlier. Although the acceleration sensor with reference to gravity and the electronic compass with reference to geomagnetism can form vertical and horizontal three-dimensional space coverage on the earth’s surface, because both of them use the earth rather than the object itself as the reference object, they cannot simulate well. the entire motion of an object. In addition, since the accelerometer is easily disturbed by the force generated during linear motion, and the electronic compass is easily disturbed by other magnetic fields such as metals and mobile phones, its application is greatly limited.

The electronic compass mainly detects the geomagnetism. Common electronic compasses are mainly based on the Hall effect. However, the geomagnetic environment is not perfect. For example, the south pole of the geomagnetism does not necessarily point to the same north on different surfaces of the earth; and at different latitudes of the earth, the angle between the direction of the geomagnetism and the horizontal direction is also different. Therefore, the electronic compass can only point to a general direction, and then correct it. In addition, electronic compasses are also susceptible to interference from magnetic fields such as metals, speakers, and antennas.

The gyroscope, a sensor that measures angular velocity, not only uses the object itself as a reference, but also has high precision, so it can be a useful supplement to other motion sensors, thus making motion detection more complete. A gyroscope can be a useful complement to an accelerometer and an electronic compass. When a three-axis gyroscope is combined with a three-axis acceleration sensor to form a six-axis motion sensor, basically all forms of motion can be detected, including parameters such as speed, direction, and displacement.

There are no more than six kinds of motion of an object, displacement in three directions of X, Y, and Z and rotation in three directions of X, Y, and Z. These six motion modes constitute the complete motion trajectory of the object. If an electronic compass is added to the six-axis motion sensor, the absolute position can be corrected while the motion trajectory is detected to achieve perfect object motion trajectory tracking. Therefore, the further development and application of the gyroscope in the future are closely related to the acceleration sensor and the electronic compass.