Research On Micromachined Gyro Drive And Detection Control System

Silicon micromachined gyroscope is based on Coriolis force mechanics principle.An electrostatic force is applied to the driving mode of the silicon gyroscope to make the gyroscope oscillate in a constant amplitude in the driving direction.When the angular velocity is input from outside,the corresponding forced vibration will be generated in the detection mode.The measured angular velocity signal can be calibrated by detecting the change of the parameters of the silicon gyroscope caused by the forced vibration.In this paper,the external control system of micro-machined gyroscope is studied.The principle analysis,simulation analysis and experimental verification of self-excited closed-loop drive control system technology,driving signal detection,comb capacitance detection technology of vacuum encapsulated gyroscope,force balance Closed-loop Detection and control technology are detailed.Firstly,the paper gives a brief overview of the micro-machined gyroscope,introduces some performance parameters,and analyses the research progress of the drive mode control system and the detection mode control system of the micro-machined gyroscope at home and abroad.According to the working principle of silicon micromachined gyroscope,a simplified mechanical model of silicon micromachined gyroscope is established.The output expressions of driving mode and detecting mode are deduced theoretically.The electrostatic force driving principle of comb capacitor,detection principle of comb capacitor and capacitor/voltage conversion circuit are analyzed.Secondly,the principle of driving closed-loop control system is analyzed,and the corresponding control system block diagram is given.According to the natural frequency and quality factor of the experimental gyroscope,the parameters of each circuit module in the loop are determined,and some circuit modules are analyzed and simulated,so that the driving hardware circuit can automatically start up quickly after power-on.Because the system can not directly get the amplitude and frequency information of the driving response signal after starting,this paper proposes CORDIC algorithm,LMS adaptive algorithm and frequency measurement method to detect the amplitude and frequency of the driving output signal,and designs the corresponding signal detection scheme block diagram,as well as the LabVIEW host computer which reads and saves the data.The signal detection system is tested experimentally.The oscillation frequency of the driving mode is 9432 Hz and the amplitude is 0.8V.The amplitude jitter accuracy is 87.5ppm.It is verified that the gyroscope oscillates at the resonant frequency with constant amplitude,which makes the Coriolis force and the measured angular velocity basically linear.Finally,the force balance detection and control technology of micro-mechanical gyroscope based on modulation and demodulation is studied in detail.Analysis results based on open-loop and closed-loop systems of the control system.The phase angle changes caused by the circuit are compensated.The control loop of the system is simulated in time domain and frequency domain with the software of MATLAB.The feasibility of the control scheme is verified theoretically.Based on the theoretical simulation results,the experimental circuit is built.The experimental results show that the scale factor of the gyroscope using the detection force balance control system is 2.8mV/°/s,the nonlinearity is 349.4 ppm,the zero bias stability is 5.93°/h at room temperature,and the zero bias stability is 397°/h at full temperature,which meets the performance requirements of inertial gyroscope.