Vibration Sensitivity Analysis And Structural Optimization Of Silicon Micro Angular Vibratory Gyroscope

Silicon micro gyroscope is a new branch of MEMS inertial sensors, which is paid much attention and applied to the military and civil field widely owing to its small size, low cost and high reliability. With the performance of silicon micro gyroscope improved, its application is becoming larger while the applicable circumstances are becoming demanding. Due to the limitation of processing technology, it is very sensitive to the environmental factors; thus limiting the applications of high-performance silicon micro gyroscope. And the vibration is one of the key environmental factors. Therefore enhancing the anti-vibration ability of silicon micro gyroscope has become one of the focus topics in the industry.The paper aimed to improve the anti-vibration performance of silicon micro gyroscope. Based on analysis of the structure characteristics and working principle, two cases of ideal structure and machining error including orthogonal error and force unbalance on vibration sensitivity of angular vibratory gyroscope are analyzed in detail. Taking the random vibration test as the prototype, combined with the model reduction method and the numerical analysis method, the vibration simulation model of silicon micro angular vibratory gyroscope was established, and the structure and the control circuit of the gyroscope were studied. At the same time, considering the random vibration response of angular vibratory gyroscope, the excitation source of the gyro system was determined. Based on the vibration simulation system model, in the case of the symmetric structure and the asymmetric structure including Centroid offset, capacitance offset and capacitance unequal spacing on the vibration sensitivity is analyzed.Through theoretical analysis and simulation, the vibration sensitivity was mainly related to the vibration intensity, the machining error and the frequency of the vibration mode. From the machining error, centroid offset was the main source of vibration sensitivity; from mode of vibration, vibration signal along the sensitive direction was a major source of the vibration sensitivity. Therefore from mode of vibration, the gyroscope structure was optimized.Finally, Analysis results were verified through the angular vibratory gyroscope random vibration test. The experimental results showed that the vibration sensitivity and PSD of vibration approximated linear relationship; The greater the machining error, the more obvious the growth of vibration sensitivity, and reaching a certain value would cause the failure of gyro; at the same time, the optimized structure of the gyroscope compared with the result of before optimization, vibration sensitivity was reduced by 70%, reaching the expected goal, greatly improved the anti-vibration performance.