Control and Rotation Rate Estimation of Vibrational MEMS Gyroscopes

There are two major control problems associated with vibrational MEMS gyroscopes: to control two vibrating axes (or modes) of the gyroscope, and to estimate a time-varying rotation rate. This paper demonstrates how a novel active disturbance rejection control addresses these problems in the presence of the mismatch of natural frequencies between two axes, mechanical-thermal noises, quadrature errors, and parameter variations. A demodulation approach based on the estimated dynamics of the system by an extended state observer is proposed to estimate the rotation rate. The simulation results on a Z-axis MEMS gyroscope show that the controller is very effective by driving the output of the drive axis to a desired trajectory, forcing the vibration of the sense axis to zero for a force-to-rebalance operation and precisely estimating the rotation rate.