Inertial sensors (Resonant Mems gyroscope)

1.       working principle

The vibration gyroscope generates gyroscopic torque by changing the direction of the vibration plane of the vibrating object. Its main body is a component that vibrates at a high frequency and a small amplitude. It uses the Coriolis effect generated by the high-speed vibrating mass when it is driven by the base to sense angular motion.

The working principle of the resonant gyroscope can be explained by the world's first practical MEMS gyroscope. Figure 1 shows a single-crystal silicon dual-mass tuning fork gyroscope developed by the Draper Laboratory in the United States. It uses the working principle of the resonant gyroscope to measure the angular velocity input Ω0 in the y direction. The vibration masses M1 and M2 are sensitive units, which can vibrate in the x and z directions. The vibration in the x direction generates motion velocity, which interacts with the angular velocity input Ω0 to generate the Coriolis acceleration in the z direction. The vibrating mass block is subjected to the Coriolis inertial force in the z direction and produces forced vibration. The vibration amplitude in the z direction represents the magnitude of the Coriolis acceleration, and the magnitude of the angular velocity input can be calculated according to a simple proportional relationship.

2.       Technology Status of MEMS gyroscopes

The biggest features of MEMS gyroscopes are low power consumption, small size, low cost and mass production. Consumer electronics have brought this feature to the extreme. The mysterious and high-end inertial instruments have been integrated into our daily lives due to MEMS technology. The MEMS gyroscopes are in our mobile phones, cars, and even in the watches we wear and the clothes we wear, serving us all the time. The military market, which has the greatest demand for high precision and high reliability, is also increasingly favoring such technical advantages. More and more small or micro aerospace and aviation have become possible to be miniaturized and scaled up due to the miniaturization of instruments. Drones are the best example.

Since 2010, the structural design and front-end processing technology of MEMS inertial sensors have become increasingly mature, and packaging technology has been a research hotspot in the past five years. Through the advancement of packaging technology, the integration of consumer electronics is getting higher and higher.

3.       Development trend of MEMS gyroscopes

In the field of consumer and automotive electronics, inertial instruments will continue the technical route of multi-axis integration. In the field of consumer and automotive electronics, inertial instruments will continue the technical route of multi-axis integration. Add 10 axes for air pressure, 12 axes for humidity and clock, the smaller the better, the more integrated the better, the cheaper the better. After the main indicators reach a certain level, the continuous improvement of the process and the introduction of new structures and new principles will continuously improve the accuracy of the instrument, the MEMS technology will be the main theme of technological development in the next 10 years.

In the field of national defense applications, the precision indicators of gyroscopes are more sensitive, and high precision and high reliability are the focus of research.