Structural Design And Error Suppression Technology Of High-Precision Resonant Accelerometer

Micromachined resonant accelerometer(MRA)is a kind of micromechanical silicon accelerometer by converting inertial force to the change of resonator frequency,which yields the advantages at miniaturization,high accuracy,large dynamic range and quasi-digital output compared with the traditional acclerometers and extends an important development direction of high-precision micro-electromechanical accelerometer.In this paper,the performance optimization of MRA is the research goal,and systematic research is carried out from the aspects of improving the sensitivity of the accelerometer,improving the accuracy of engineering applications,and suppressing temperature drift.The research work of the thesis is summarized as follows:The working principle of the resonant accelerometer is analyzed,and the method to improve the scale factor under the constraints of the current process and package size is analyzed.The influence of factors and the selection principle of related parameters.According to the previous processing experience,taking into account the yield,two large scale factor structures are finally designed.The scale factors are 932Hz/g and1012Hz/g respectively,and the processing yield can reach 100%.After testing,the scale factor is as high as 1002Hz/g,and the bias stability is 0.122μg in 1 hour.In order to solve the problem that the low-frequency modal is easily excited and causes the mass to move along the sensitive axis,a series of simulation analyses were carried out to increase the frequency of the first-order modal,including the influence of the parameters of the support beam and lever on the first-order modal frequency.Finally,four structures are designed,the first-order modal frequencies are 2086 Hz,2556Hz,2782 Hz,3173Hz,and the harmonic response simulation analysis of the four structures is carried out,which are improved compared with the previous structures.In order to further reduce the movement of the mass in the sensitive direction in the vacuum state,a passive damping structure and an active damping structure are initially designed to increase the damping coefficient of the translation of the mass.Thereby,the amplitude of the excited motion of the mass is greatly reduced.Aiming at the temperature drift problem of the accelerometer caused by the adhesive stress in the patch process,the tooling during the patch process is designedto ensure the consistency of the patch.Aiming at the problem that the temperature measurement of the resonator that measures acceleration on both sides is easily coupled into the influence of acceleration,an additional temperature measurement resonator is designed,which is perpendicular to the sensitive direction of acceleration,which is used for temperature characterization,and the effect of acceleration on temperature measurement is analyzed by simulation.The effect will not exceed 1.2ppm.Then,the temperature control system was optimized for miniaturization and low power consumption,a constant temperature control system with a prototype with on-chip temperature control was designed,and the constant temperature system was tested.Finally,temperature can be stabilized to within ±0.005°C,the temperature rise range can reach 37.5°C under 10 V voltage.The 48 h bias stability decreased from 10.14μg to3.48μg after adding temperature control.Finally,the performance tests of the two types of accelerometer prototypes are carried out.The highest sensitivity of the prototype is 1002.63Hz/g,and the best zero bias stability is 0.122μg.The experimental results indicate that the MRA has the potential on high-precision inertial navigation,precision weapon guidance and sensitive gravimetry applications.