MEMS gyroscope is the third generation gyroscope, which has the characteristics of small size, low power consumption, low cost and can be mass-produced. Gyroscope is a device for sensing and maintaining direction based on the theory of conservation of angular momentum. In 1850, French physicist Leon Foucault found a phenomenon in the process of studying the earth's rotation, that is, the high-speed rotating rotor due to inertia makes the rotation axis always point to a fixed direction, he named this device as the gyroscope, and proposed the application of the gyroscope, the first gyroscope used to assist the hull to maintain stability in navigation. In 1923, the German mathematician Schuler proposed the famous Schuler tuning principle, which makes the gyroscope applied to the inertial navigation system.

This paper will explain the development history of gyroscopes, which can be divided into three generations according to different principles.



History of gyroscope development


Gyroscope is a kind of sensor, with precession and fixed axis, can be sensitive to changes in carrier attitude angle and angular velocity, and has the ability to achieve measurement tasks in any environment. Therefore, it is widely used in aviation, aviation, aerospace and other fields. From the 20th century

The gyroscopes widely used from the beginning to the present can be divided into three generations: the first generation of gyroscopes is also known as mechanical gyroscopes, the design principle is based on the basic principles of mechanics, typical gyroscopes are liquid floating gyroscopes, electrostatic gyroscopes, dynamic tuning gyroscopes, etc.; The design principle of the second generation of gyroscopes is based on the Sagnac effect of atoms, typical products are laser gyroscopes, fiber optic gyroscopes, etc. The third generation of gyroscopes is a MEMS gyroscope, the basic principle is the Coriolis vibration effect.



1. History of the first generation of gyroscopes
1.1 Liquid float gyroscope
Liquid floating gyroscope is a kind of gyroscope that uses the Archimedean principle to overcome gravity through the buoyancy of high-density liquid so that the supporting bearing can be unloaded. Its basic working principle is as follows: First of all, the float is filled with inert gas, and then the rotor in the gyroscope is sealed with these gases, and the float ball is suspended in the fluorine oil, when the static balance is very accurate and the control temperature reaches a certain level, the liquid buoyancy and gravity will cancel each other, the system will maintain balance, and the friction torque on the bearing will become very small, so the drift error of the liquid floating gyroscope is very small.



1.2 Electrostatic gyroscope
Electrostatic gyroscope, also called electrostatic support gyroscope, is a spherical rotor free gyroscope. Its characteristic is that the use of a strong electric field in the ultra-high vacuum will produce a supporting force, replacing the mechanical bearing so that there is almost no mechanical contact part in the system, so the drift error of electrostatic gyroscope is also very small, and the precision of high-precision electrostatic gyroscope can reach 10-6 (°)/h (magnitude).



1.3 Power tuned gyroscope
Dynamically-tuned gyroscope, also known as flexible gyroscope, is a gyroscope supported by a flexible joint composed of two pairs of orthogonal torsion bar and balance ring frame through the gyroscope rotor, which has been widely used in navigation equipment. The basic principle is to use two pairs of orthogonal torsion bar and balance ring frame, the dynamic effect makes the system generate a negative elastic moment, and the elastic torsion bar will produce a positive moment, after the two cancel each other, the rotor will be in a state of balance, thereby reducing the drift error of the gyroscope.



2. History of the development of the second generation gyroscope
2.1 Laser gyroscope
Laser gyroscope is a kind of gyroscope based on Sagnac effect, with bidirectional traveling wave laser as the core. Sagnac effect is that if two beams of light in opposite directions are emitted in the same optical path, there will be an optical path difference when the two beams of light converge to a place. When the characteristics of the two beams of light are the same, the size of the optical path difference is positively correlated with the rotational angular speed, which makes the laser gyroscope sensitive

Sense the rotational angular velocity to complete the measurement.



2.2 Optical fiber gyroscope
Fiber optic gyroscope is a kind of gyroscope based on the Sagnac effect of atoms and the optical fiber coil. Compared with the laser gyro, the difference is only that the fiber optic gyro propagates in the optical fiber, and the propagation channel of the laser gyro is the resonant cavity. Fiber optic gyroscope is also widely used in aircraft, ships, tactical equipment, is a good performance of the gyroscope.



3. Development history of the third generation gyroscope
MEMS gyroscope has a very fast development rate in recent years, it is based on the vibration object can sense the angular speed of this characteristic and combined with micron/nanotechnology design of a gyroscope, has a very broad application prospect and development space, has been widely concerned in the world.

MEMS gyroscope was born in the 1980s, typical products are Honeywell HG series MEMS gyro, Arnaud Semiconductor ADI16136 gyroscope and so on. Due to the large drift error of MEMS gyroscope, it was previously used in the field of low-precision navigation, and now the technology is more mature, more and more methods to eliminate errors, MEMS gyro is also applied in the field of high precision.

MEMS, as the latest generation of gyroscopes, has become the benchmark of the market and The Times, and many industries choose to use MEMS gyroscopes to replace other gyroscopes, because MEMS gyroscopes have many advantages, such as small size, low cost, easy production and industrialization. The MEMS gyroscope has also been extended from the previous consumer level to the current navigation level and consumer level, navigation level MEMS gyro can be applied to higher precision fields, such as drones, aerospace, drilling, etc., while the accuracy of tactical level MEMS gyro is slightly lower than the navigation level, suitable for the accuracy requirements are not very strict and there is a cost control demand. For example, ER-MG2-50/100 and ER-MG2-300/400 are navigation-grade MEMS gyroscopes, but they are nord-finding gyroscopes for ground navigation and air/sea navigation gyroscopes, respectively.



Conclusion


This paper introduces 6 kinds of gyroscopes, and analyzes their working principle, and elaborates MEMS gyroscope in detail. I hope you can understand MEMS gyroscope through this article. If you are interested in learning more about MEMS gyroscopes, please contact us.

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