Research On Key Technologies Of Electromagnetic Drive Amplitude Stabilization Control For MEMS Gyroscope

With the rapid development of microelectromechanical systems,the micro-electromechanical gyroscope(MEMS)is a new type of inertial sensor.It has been widely concerned because of its small size,low power consumption,strong impact resistance and other advantages,and has been rapidly developed at home and abroad.Due to the limitations of the existing processing conditions,measurement and control circuits,the accuracy of the MEMS gyroscope is generally low.From the overall development trend,the main research directions of the MEMS gyroscope are: structure design,process design,measurement and control circuit design.In this paper,the amplitude stabilization control circuit of the measurement and control circuit of the MEMS gyroscope is studied.Firstly,the basic working principle of the MEMS gyroscope is introduced.According to the dynamic model of the gyroscope,the expressions of driving displacement and detecting displacement of the MEMS gyroscope are derived.The principle of electromagnetic drive of gyroscope and magnetoresistance detection of tunnel are introduced emphatically.The factors that cause the resonant frequency drift and amplitude instability of the MEMS gyroscope are analyzed.The influence of the driving resonance and amplitude stability of the MEMS gyroscope on the performance of the gyroscope is expounded,and the importance of closedloop control is derived.Then,the basic components of PLL and AGC circuits are introduced,and their respective mathematical models and working principles are introduced in detail,and the related performance of the control system is analyzed.A closed-loop drive control model based on PLL frequency control and AGC amplitude stabilization control is constructed.The lock-in characteristics of PLL algorithm to resonant frequency and the dynamic characteristics of AGC algorithm to amplitude control are verified by MATLAB simulation,and the double closedloop control system of gyroscope is simulated at the system level in MATLAB.Finally,the hardware system and software system of measurement and control are designed and validated respectively.The hardware system design includes analog interface circuit design and digital measurement and control circuit design.The analog interface circuit is mainly designed for the weak voltage/current detection circuit module,while the digital measurement and control system is mainly designed for the ADC acquisition module,the main control module of the FPGA,and the communication module.The design of software system mainly includes hardware-driven design and hardware implementation of key algorithms.The hardware driver is mainly for ADC,DAC and communication chips.The hardware implementation of key algorithms is mainly DDS algorithm,FIR algorithm and CORDIC algorithm on the FPGA.