Research On Mode Switching And Performance Optimization Technology Of Silicon-Micro Axisymmetric Gyroscopes

As one of the common MEMS inertial sensors,the silicon-micro axisymmetric gyroscope can be operated in rate and rate-integrating modes,respectively,for measuring angular rate and angle.The rate mode is characterized by high-precision detection,while the rate-integrating mode has the advantage of a wide range measurement.To achieve highperformance silicon-micro axisymmetric gyroscope with above merits,it is necessary to research the mode switching technology and optimize performance of two operational modes.Based on the cobweb-liked disk resonator gyroscope in the typical axisymmetric structure,we proposed a mode switching control system to realize the automatic switching between the two modes at the preset angular rate thresholds.And we demonstrated the performance optimization of rate-integrating mode,rate mode,and control system in this dissertation.The main research contents are as follows:Firstly,after an adequate investigation of the rate and rate-integrating modes,especially the performance characteristics of them under different input rates,the switching control system was analyzed and simulated theoretically.The system switched automatically between the high-precision rate mode at low rates and the rate-integrating mode at high rates through angle closed/open-loop control by comparing the output rate with preset switching thresholds.Thereby,the issue that angle output noise affect the control system in practical applications was raised in our study.Secondly,on the basis of above theoretical models,we focused on the influence of the input angular rate on the vibrating amplitude of the gyro in rate-integrating mode.And we proposed a rate output method to extract the angular rate through a demodulation and a combinatorial calculation of amplitudes of two resonance modes to ensure the switching stability.Then the influence of asymmetric error is analyzed,and the related error is compensated to reduce its threshold.In rate mode,the rate control of the algorithm is analyzed,and the stiffness error term in the control variable is replaced by a constant,which reduces the output noise of the gyro.To further improve the performance of the system,a precession angle tracking algorithm is developed to feedback on the real-time oscillator pattern of the gyro when the gyro switches back to the rate mode.Thereby,the mode pattern is closer to the reference value of the angle control loop,which can improve the stabilization time of the rate mode.Finally,the performance of the axisymmetric gyroscope,that is cobweb-like disk resonator gyroscope,through the optimized mode switching control system is tested in this dissertation.The test resonant frequencies of the x-mode and the y-mode are 5046.76Hz and 5045.1Hz.The test quality factors are 136252 and 135606.The control system implements effective steering control of the gyroscope with a switching delay of 10ms from rate mode to rate-integrating mode at preset rates±150°/s and 100ms from rate-integrating to rate mode at ±75°/s.The experimental results show that the bias instability and the angle random walk of the gyro can reach 0.106°/h and 0.011°/(?),respectively,and the input range is over±50000/s,providing a rate detection with high accuracy,low noise,and large range.The results also verify the validity of the research contents,which provide strong technical support for applying silicon-micro high-performance gyros in inertial navigation or other fields.