Study On In-phase Errors Self-compensation Technology Of Silicon Micro Gyroscope

Gyroscope is a kind of inertial instruments which measures the angular rate of the carrier relative to inertial space.Compared with traditional gyroscopes,silicon micromachined gyroscopes have the advantages of small size,light weight,low cost,low power consumption and easy to integrate with electronic circuits,which make them have broad application prospects in both civilian and military fields.However,microelectromechanical systems(MEMS)have been gradually revealed to the disadvantages of poor environmental adaptability in engineering application.Therefore,how to solve the stability and reliability in the variable mechanical and temperature environment is the critical point in engineering application of MEMS.In-phase error can not be isolated from useful signals and can be easily affected by temperature and stress,which leads to bias drift.In this study,the vector commutation theory of kinetic moment is used for reference,that is,under the condition of defining the mechanism of in-phase error,the online self-compensation method of in-phase error can be realized by driving mode periodic reversal,and the bias stability of micromachined gyroscope can be effectively improved.Firstly,the error mechanism of gyroscope was analyzed,which includes quadrature error and in-phase error.Once the quadrature error is eliminated by demodulation,in-phase errors due to asymmetrical comb gap will become the main errors source which is sustainable to temperature and stress.The theory analysis of in-phase error due to asymmetrical comb gap provides theoretical guidance for the research of self-compensation technology.Secondly,drawing lessons from the self-compensation theory of traditional mechanical gyroscopes,an on-line self-compensation method based on the commutation principle of moment of motion was proposed to decrease the in-phase error caused by asymmetrical driving comb gap.The corresponding measurement and control system of gyroscope were designed.Two-stage integrated interface circuit was adopted,a new amplitude-limited drive circuit based on comparator was used to replace the traditional AGC loop,and a switch was added to drive loop to realize the polarity reversal so as to compensate the in-phase error.The self-compensation algorithm in hardware circuit and software was studied.Based on the method of periodic reversal of driving mode,the self-compensation technology of driving induced error was studied.Aiming at the deterioration of dynamic characteristics caused by the driving mode periodic reversal,based on the linear time-varying signal filtering algorithm,the gyroscope angular rate information fusion technology in the process of mode reversal was studied to solve the reasonable matching problem of dynamic characteristics and long-term stability of silicon micromechanical gyroscope.Finally,the silicon micromachined gyroscope with on-line self-compensation measurement and control system was tested under mechanical and temperature environment.The results show that the bias instability of silicon micromechanical gyroscope was improved from 24.6°/h to 9.7°/h.Bias can be less affected by stress,temperature and the self-compensation system is feasible and achieves the desired effect.