Structural Design And Fabrication Process Of Quatrefoil Microgyroscope

The vibrating microgyroscope is an angle measurement sensor based on the Coriolis Effect. For the advantages of small size, low weight, low power, fast startup, low cost, high reliability, being easy to be digital and et al, the microgyroscope is becoming more and more popular in the applications of military and civil fields. The quatrefoil microgyroscope is a totally symmetrical structure, the performance of which is closely connected with the structural design, fabrication process. This dissertation focuses on the structural design and fabrication process. Subsequent research contents are included in this dissertation.1. The basic structure of the quatrefoil microgyroscope is designed. The dynamic model of the microgyroscope is established. The expressions of the key kinematical parameters are deduced based on the dynamic model. The sensitivity is analyzed, and the crucial factors affecting the sensitivity are also found. The air damping of the quatrefoil gyroscope is analyzed and simulated. According to the special structure of the quatrefoil gyroscope, some measures to decrease the squeeze air damping are put forward.2. The structural analysis and design of the quatrefoil microgyroscope is studied. Four kinds of support structure for the quatrefoil microgyroscope are analyzed. According to some factors, including mode separating, support energy loss and the current fabrication process, the flat support structure is chosen for the structural design of the quatrefoil microgyroscope. The main structural parameters of the quatrefoil microgyroscope are designed. The influence of structural parameters on the mode frequency is studied. The influence of the errors of the structural parameters is analyzed. It provides guidance for the fabrication process designed for the quatrefoil microgyroscope.3. The fabrication process is deeply studied, including the pre-embedded mask wet etching of the silicon structure, the wet etching of the Pyrex glass, the fabrication process of the inertial mass pole and support pedestal. Based on the fabrication process above, the assembly process of the microgyroscope is analyzed, the assembly errors are obtained and some steps for improving the assembly process are taken consideration.4. A fabricated quatrefoil microgyroscope is characterized, including static capacitance test, mode test and Coriolis force test. The static capacitance is 3.289pF,and the error between the capacitance test result and the theoretic value is less than 5%;The drive frequency and sense frequency are 2.676 KHz and 2.699 KHz at atmosphere pressure, and the Q-factor values are 10.5 and 17.4, respectively; after being packaged in the vacuum, the drive frequency and sense frequency are 2.689 KHz and 2.6721 KHz, and the Q-factor values are 432 and 672.3, respectively.