Real Time Error Suppression For Silicon Micro Gyroscope Based On FPGA

Silicon micro gyroscope,with many advantages,such as small size,light weight,low power consumption,low cost,high reliability and mass production,is widely used in industrial control,aerospace,automobile,consumer electronics and military applications,for the rapid development of MEMS technology.Due to the limit of MEMS process,the bias and scale factor of gyroscope have large errors under different environmental conditions,which is the main constraint on development of gyroscope.In order to reduce the environmental sensitivity and improve the long-term stability of silicon micro gyroscope,this paper studies the real-time error suppression method based on FPGA for the double mass silicon micro gyroscope independently developed and designed by I-MEMS lab.The main innovations and research work are as follows:Firstly,the basic theory of silicon micro gyroscope is introduced from three aspects:the basic structure,dynamic model and principle of measurement and control.And the correlation coefficient is deduced;Then the error suppression scheme based on digital technology is introduced from three aspects:the carrier of digital signal processing,the selection of basic parameters and the error analysis in the process of digital signal processing.Then,the in-phase error self calibration technology of silicon micro gyroscope is studied.Through the theoretical analysis of the source of in-phase error,the main mechanism of in-phase error is determined.On this basis,the scheme of driving mode inversion suppression is proposed,and the in-phase error suppression is realized.In order to solve the problem of deterioration of dynamic performance caused by the above methods,based on the linear time-varying digital filter,the research on the information fusion technology of gyroscope angular velocity in the process of modal inversion is carried out,which solves the problem of reasonable matching of dynamic characteristics and long-term stability of silicon micro gyroscope.Next,the research on self compensation of scale factor error of silicon micro gyroscope is carried out.By analyzing the scale factor mathematical model of silicon micro gyroscope,the scale factor error can be divided into drive shaft vibration rate error and detection sensitivity error.In view of the main sensitivity errors of the detection shaft,a compensation scheme based on obtaining the real-time drive shaft and the detection shaft resonance frequency difference is determined.Through the design of low-power,high-precision frequency measurement scheme,the resonance frequency of the drive shaft is obtained;by adding the reference signal scheme,the real-time resonance frequency of the detection shaft is obtained.Finally,according to the test rules of micro gyroscope,the performance of silicon micro gyroscope is tested.In the experiment of in-phase error suppression scheme,the output of bias is reduced by 3.9~o/s.In the pressure experiment,it can be found that the output of gyro does not change with the change of external pressure.In the whole temperature experiment,the change of bias is reduced from 9.9~o/s to 4.0~o/s.In the scale factor suppression experiment,the error of scale factor variation is reduced from 5.53%to 0.60%in the whole temperature range.