MEMS gyroscope is an inertial sensor used to measure angular rate or attitude angle. Because of its small size, low power consumption, easy mass production, low cost, it has been paid attention to and widely used in many industries. In recent years, MEMS technology has been developing rapidly, its performance is becoming more and more excellent, and the technology is becoming more and more perfect. We can judge the performance of MEMS gyroscope according to many influencing factors, damping is one of them. This paper aims to analyze the influence of damping on MEMS gyro, and introduces the concept and function of damping, classification and damping model.

Concept and function of damping in MEMS gyroscope

Damping is a method of limiting vibration, which is the dissipation of vibration energy over time and distance in solid media and structures. Similar to the absorption of sound in air, damping occurs whenever there is any type of friction, reducing motion and dispersing energy. The damping capacity of each material is called its loss factor, which represents the ratio between the energy dissipated during each cycle and the energy remaining in the system. Many people confuse damping with friction, which is a dissipative force acting on a system. Friction can cause or be a factor in damping, but friction and damping are not the same thing.

Damping is an effect within or on an oscillating system that has the effect of reducing or preventing its oscillation. In MEMS gyro, the damping coefficient and quality factor of its core structure are important factors affecting the dynamic response and performance of the gyro.

In simple terms, this is what happens with door or drawer springs, where damping prevents shock when opened or closed, thus protecting them and protecting the system.

Classification of damping in MEMS gyroscope

The damping of MEMS gyro core structure is mainly composed of the following two aspects:

Structural damping: it comes from inside the material of the mechanical structure of the watch movement and is mainly affected by the material characteristics and structural dimensional characteristics.
Gas damping: from inside the gyro chip package.
The structure damping of MEMS gyro is much less than that of gas under normal temperature and pressure, so the structure of gyro core is mainly determined by gas damping. Due to the Brownian motion of the gas molecules inside the chip package, the output signal of the gyroscope will contain a lot of random noise, so most of the current high-performance MEMS gyroscopes are designed in high vacuum package. However, due to the high technical level and certain leakage rate for MEMS gyro to achieve high vacuum packaging, non-vacuum packaging is still used for some applications that require long-term storage and require reliable and stable performance. The gas damping coefficient inside the gyro chip package is not only related to the characteristic parameters of the gas state, such as temperature, pressure, etc., but also depends on the way of gas flow and the geometry characteristics of the watch core structure. Therefore, gas damping becomes a factor that we need to focus on analysis.

According to the different ways of relative movement between the gas fluid and the watch movement structure, gas damping can be divided into::

Synovial damping
Pressure film damping


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