Signal Processing System Based On Phase Modulation-demodulation Technique Of MOEMS Accelerometer

MEMS accelerometers are widely used in different fields,due to their small size and high precision.Especially in inertial navigation systems,MEMS accelerometers play important roles.Combined with MEMS technology,MOEMS accelerometers have the strong ability of anti-electromagnetic interference and higher precision.However,the output signal of MOEMS accelerometer is weak signal and the useful signal is submerged in noise.Therefore,it is difficult to further breakthrough at the precision.To improve the resolution and lower the noise,the research on signal processing system has a vital importance.To eliminate the impact and decrease the signal distortion,the technique of phase modulation and demodulation is introduced to this accelerometer by applying a sinusoidal signal to a piezoelectric translator(PZT)amounted to the accelerometer.Finally,test the interference fringe produced from the modulated beam and reference beam and demodulate the test signal.By this way,the MOEMS accelerometer improved the signal-to-noise ratio,decreased the noise greatly and realized the accurate measurement.Firstly,the measurement principle,the development tendency,advantages and disadvantages of the micro-accelerometer were introduced.Secondly,a brief description of the MOEMS accelerometer based on grating interferometer was given.Meanwhile,signal processing circuit to test the MOEMS accelerometer without modulation and demodulation module was designed.Thirdly,After analysing the result,the signal processing system of MOEMS accelerometer based on Phase modulation and demodulation technique was brought in.In this dissertation,we have simulated a modulator and an orthogonal phase-lock demodulator based on Lab VIEW.In the phase modulation system,in order to further improve the accuracy,we applyed a sinusoidal signal to a piezoelectric translator(PZT)amounted to the accelerometer.The features of PZT and the modulation parameter were described.Then the demodulator circuit was completed based on Lock-in Amplifier.After testing the whole system,the noise was decreased under 20 mV.Finally,a summary of the research was involved,and the prospects for the future work were proposed.