Analysis and design of a 3rd order velocity-controlled closed-loop for MEMS vibratory gyroscopes.
The time-average method currently available is limited to analyzing the specific performance of the automatic gain control-proportional and integral (AGC-PI) based velocity-controlled closed-loop in a micro-electro-mechanical systems (MEMS) vibratory gyroscope, since it is hard to solve nonlinear functions in the time domain when the control loop reaches to 3rd order. In this paper, we propose a linearization design approach to overcome this limitation by establishing a 3rd order linear model of the control loop and transferring the analysis to the frequency domain. Order reduction is applied on the built linear model's transfer function by constructing a zero-pole doublet, and therefore mathematical expression of each control loop's performance specification is obtained. Then an optimization methodology is summarized, which reveals that a robust, stable and swift control loop can be achieved by carefully selecting the system parameters following a priority order. Closed-loop drive circuits are designed and implemented using 0.35 μm complementary metal oxide semiconductor (CMOS) process, and experiments carried out on a gyroscope prototype verify the optimization methodology that an optimized stability of the control loop can be achieved by constructing the zero-pole doublet, and disturbance rejection capability (D.R.C) of the control loop can be improved by increasing the integral term.
Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China. yanghg@mail.ie.ac.cn.
Huan-ming
HM
Wu
Hai-gang
HG
Yang
Tao
T
Yin
Ji-wei
JW
Jiao
D000054:Acceleration; D061725:Accelerometry / Q000295:instrumentation*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D008962:Models, Theoretical; D014159:Transducers; D014732:Vibration