Triaxial Accelerometer Resonant Control Circuit

Resonant Slicon Mcromechanical Acelerometer is a kind of micro inertial sensors which works at the theory of mechanical vibration and is used to measure the acceleration of object. The resonant accelerometer is far better than the traditional acceleration sensors in the ability of anti electromagnetic interference and it has stable output. At present, multiaxial is the development trend of micro electro-mechanism accelerometer. There have been three-axis accelerometers based on capacitance, piezo-resistive, tunneling current and so on. This paper discusses the closed loop control circuit and frequency detection circuit of a new resonant three-axis accelerometer, the core content is the closed loop control circuit and frequency detection circuit. Thesis mainly from the following several parts:(1) This paper expounds the development history of domestic and foreign micromechanical accelerometer and the corresponding measurement and control circuit.Also the future development direction of micromechanical accelerometer is introduced, thus, the purpose and significance of this paper is clear.(2) The mathematical model and the theoretical formula of the resonant accelerometer was established based on the basic principle of resonant accelerometer.This is the theoretical basis of this paper.(3) A closed-loop drive circuit of the three axis resonant accelerometer is designed.The closed loop control system was optimized throw analysising the key technologies such as signal extraction and the control of phase and amplitude to make the resonant accelerometer work stability.(4) Through analying the way of frequency measurement, A frequency measurement algorithm and corresponding frequency measurement schematic based on FPGA was designed to detect the frequency of the triaxial resonant accelerometer timely.The acceleration mesured can be calculated by the frequency detected above.(5) The printed circuit board was manufactured and the controlling and detecting circuit of the resonant three-axis accelerometer was realized too.The PCB was tested and the experiment of scale factor, zero bias stability, zero partial repeatability, cross shaft coupling test, centrifuge was carried out.By analysising the experimental results and summarizing the circuit performance we can have a look of the trend of resonant three-axis acceleromete.