Research On Scaling Factor Self-Calibration Technology Of Silicon Micro Gyroscope

Silicon micro gyroscopes is an angular rate sensor,which is the core component of inertial navigation and attitude control systems.With many advantages,such as small size,light weight,low power consumption,low cost,high reliability and mass production,silicon micro gyroscope is widely used in industrial control,aerospace,automobile,consumer electronics and military applicationsDue to the error of MEMS process,before put into practical application it is inevitable for the silicon micro gyroscope to carry on the process error.It is inevitable to calibrate the silicon micro gyroscopes.The traditional calibration of the silicon micro gyroscope requires complex mechanical equipment,which leads to the low efficiency of the calibration,the cost of manpower and material power,and the extension of its R & D cycle.It is of great significance to study the calibration of scale factor of silicon micro gyroscope.In addition,the scale factor of silicon micro gyroscope will change with the change of environment when it works.It is important to study how to solve the scale factor online calibration in other environments such as temperature.Firstly,on basis of studying the measurement and control circuit of silicon micro gyroscope,the main parameters affecting the scale factor of silicon micro gyroscope are analyzed.The principle of substituting virtual Coriolis force for real Coriolis force in static calibration of silicon micro gyroscope is studied.In static calibration,the hardware circuit and upper computer software needed in static calibration are designed.The extraction method of signal parameters is also studied.Then we present a self-calibration method for a batch of MEMS gyroscopes based on virtual Coriolis force to obtain their scale factor and bandwidth.An electrostatic force is added in the detection axis of the silicon gyroscope to simulate the real Coriolis force to calibrate its scale factor and bandwidth.Besides,the test results show that the measured bandwidth is 354.3Hz by the virtual rate-table method with a maximum phase error of 3.39 deg,which are in close agreement with the simulation result 349.5HzThe on-line calibration principle and overall verification scheme of silicon micro gyroscope are studied and designed.According to the mathematical model of scaling factor,the on-line calibration of scaling factor is divided into the vibration rate calibration of driving shaft and the sensitivity calibration of detection.A scheme for calibrating the vibration rate of driving shaft of silicon micro gyroscope by using the 3-fold frequency characteristic of the non-linear stiffness coefficient is proposed.The method of calibrating the vibration rate of the driving shaft by using the relationship between the amplitude ratio of the 3-fold frequency signal and the harmonic signal and the vibration frequency of the driving shaft.In the calibration of detection sensitivity,firstly,it is analyzed experimentally that the change of detection sensitivity of silicon micro gyroscope is mainly caused by the change of detection axis gain.Therefore,the corresponding calibration algorithm is designed.Finally,according to the designed online calibration scheme,the influence of the vibration rate of the driving shaft and the detection sensitivity on the on-line calibration of the scale factor of the silicon micro gyroscope is studied.Therefore,on-line calibration of two parameters is used to calibrate the comparative factor experiment on-line.Experiments show that the change of scale factor is mainly affected by the change of detection sensitivity.However,the calibration accuracy is higher when the vibration rate and detection sensitivity of the driving shaft are used for comprehensive calibration.Through comprehensive calibration,the maximum error is reduced from 21.6% to less than 1.29% after calibration of scale factor in the whole working temperature range.