Research On Self-calibration Technology Of Acceleration Sensor With Integrated MEMS Micro-vibration Platform

The self-calibration technology of MEMS sensor based on micro-vibration platform has the advantages of online calibration,miniaturization and integration.However,during the integration process of MEMS sensor and micro-vibration platform,the alignment degree of the integrated position of sensor and micro-vibration platform,the signal transmission accuracy of the tested signal after passing through the micro-vibration platform and other factors will affect the calibration accuracy of the sensor.Based on this,this thesis studies the self-calibration technology of MEMS sensor,the integrated position deviation of sensor and its influence on calibration accuracy.The main research contents include:(1)A grid capacitive biaxial acceleration sensor is designed to integrate MEMS microvibration platform,and the sensitivity,working bandwidth and signal coupling degree of the sensor are studied by finite element simulation analysis.The sensor sensitivity is 55.87 f F/g,the working bandwidth is 359 Hz and the signal coupling degree is less than 0.06%.(2)Aiming at the problem of the integrated position deviation of the sensor and its influence on the calibration accuracy,a 12mm×12mm MEMS micro-vibration platform is designed,which is mainly composed of a central platform and four pairs of detection capacitors.The central platform is used to integrate the sensor and the four pairs of detection capacitors are used to detect the position deviation of the sensor.The sensitivity,range,working bandwidth and damping of the micro-vibration platform are studied by finite element simulation analysis.The results show that the sensitivity of the micro-vibration platform is 0.18 p F/g,the range is 30 g,the working bandwidth is336 Hz and the quality factor is 33.60.The influence of the integrated sensor on the sensitivity,range,working bandwidth and damping of the micro-vibration platform,as well as on the sensitivity and working bandwidth of the sensor itself,is also studied.In addition,the simulation results show that the deviation of integrated position will greatly reduce the actual sensitivity of the sensor,thus affecting the self-calibration performance of the sensor.(3)The position deviation between the sensor and the MEMS micro-vibration platform will affect the performance of the whole sensing system.The simulation results show that there is a positive linear correlation between the detection capacitance of the micro-vibration platform and the position deviation of the sensor.When the sensor deviates along the x axis and y=x direction,the differential capacitance sensitivity of micro-vibration platform position detection is 0.18 f F/μm and0.12 f F/μm,respectively,which proves that micro-vibration platform has the function of detecting the position deviation of sensor integration.By optimizing the structural parameters and output performance of the micro-vibration platform through simulation,the sensitivity of the microvibration platform is improved by 23.65% under the same vibration load.(4)The preparation technology of MEMS micro-vibration platform is developed,and the integrated position deviation detection experiment of micro-vibration platform and sensor is carried out.Under the condition of fixed acceleration and different offset errors,the test results show that the differential capacitance sensitivity of micro-vibration platform position detection is 0.13 f F/μm and 0.16 f F/μm,and the nonlinearity is 0.2% and 0.8%,respectively,when the sensor deviates along the x and y directions.Under the fixed offset error of 200μm,when the acceleration of 1-5g acts on the micro-vibration platform,the sensitivity of x+/y-and x-/y+ capacitors of micro-vibration platform is 0.27 p F/g and 0.23 p F/g,respectively.The sensitivity of differential capacitance in x and y directions is 38.13 f F/g and 39.03 f F/g respectively.Finally,in order to convert the output capacitance of MEMS micro-vibration platform into voltage for subsequent signal analysis,a C-V conversion circuit with a conversion ratio of 0.02V/p F is designed.The test results show that the output capacitance of MEMS micro-vibration platform is linear with the voltage value.