Adaptive control of a MEMS gyroscope using Lyapunov methods

Abstract

Two adaptive controllers for a vibrational MEMS gyroscope are described. Both controllers tune the drive axis natural frequency to a preselected frequency, regulate the amplitude of the drive axis vibration, cancel out quadrature error due to stiffness coupling, and drive the sense axis vibration to zero for force-to-rebalance operation. The first controller is based on an averaged, low frequency model, and the second is based on the full gyroscope model. Both controllers are successfully simulated for the Berkeley Z-axis gyro. The Lyapunov function used is critical in obtaining a good transient response, especially for the force-to-rebalance and automatic gain control loops. To implement the full model controller with displacement measurements only, and no velocity measurements, the controller is approximated.