Study Of Batched Calibration Of MENS Capacitive Sensor

Traditionally, high-precision MEMS accelerometers are calibrated by mechanical vibratingtable. But this method is inefficient and complicated, especially the MEMS accelerometer is batchproduction. Therefore, this paper studies a dynamic self-calibration technique of high-precisionMEMS capacitive accelerometers to raise efficiency by driving the moving electrode to vibrate insinusoid through dynamic electrostatic forces.In chapter.1, the destination and significance of the paper are presented. First, the destination,significance and classification of sensor calibration are introduced. Then some common calibrationmethods of MEMS accelerometers are shown. Next, the emergence, development and currentsituation of MEMS accelerometers self-calibration are introduced, as well as the developmenttendency. After that, the destinations of the paper are mainly introduced. Finally, the main contentand arrangement of the paper is shown.In chapter.2, the dynamic self-calibration of high-precision MEMS accelerometers is studied.First, working principle of area changeable and gap changeable capacitive accelerometers isintroduced. Then electrostatic actuation principle of capacitive sensors is shown. Afterwards,mathematic model of capacitive accelerometers is analyzed. At last, the dynamic self-calibrationmethods in open-loop and closed-loop circuit are studied.In chapter.3, the influence of fringe effect on the self-calibration precision is studied. First,fringe effect and its influence on capacitance are introduced. Then the influences of fringe effect onself-calibration precision in open-loop and closed-loop circuit are studied. At last, the results aimedat the sensor in this paper show: the self-calibration error is only0.18%in closed-loop circuit,which is approach to the absolute calibration error of laser interferometer (0.5%-1%) and can satisfythe demand of high-precision sensors. In open-loop circuit, the fringe effect influences theself-calibration obviously and the error reaches24.2%, but it can be reduced to1.49%by correctingthe actuation voltage, and can also satisfy the demand some high-precision sensorsIn chapter.4, the influence of DRIE progress error (slope angle of comb) on the self-calibrationprecision is studied. First, the DRIE progress and its influence on electrostatic force is introduced.Then the influences of DRIE progress error on self-calibration precision in open-loop andclosed-loop circuit are studied. At last, the results aimed at the sensor in this paper show: whensensor is in close loop circuit, the self-calibration error caused by DRIE progress is obvious, theerror of self-calibration is about10%when the slope angle is0.1;32%when the slope angle is0.5; and pull-in occurs when the slope angle is0.5. When sensor is in close loop circuit, the error of self-calibration is less than0.6%when the slope angle is less than0.5, which provesthat the effect of slope angle is so small that can be neglected.In chapter.5, a new capacitive accelerometer model with self-calibration function is designed.First, the whole structure and specific parameters of new model are shown. Then modal analysisand static sensitivity analysis are simulated. Finally, calculation proves the new model can improvethe actuation ability and increase the self-calibration range, proving the new accelerometer model isfeasible.In chapter.6, the achievements of the paper are briefly summarized and the further researchwork is expected.