A Drive Control Scheme Based on Phase-control for Silicon Micromechanical Gyroscopes

Abstract

A drive control scheme based on phase-control for silicon micromechanical gyroscopes (SMG) is studied and implemented. By analyzing the dynamical characteristics of the drive mode, the elementary principle of phase control scheme upon which the control loop is built is described and the stability of the loop is presented using the theory of self-sustained oscillation. The phase model of the loop is modeled where a special factor is introduced to realize the conversion from phase-error to frequency-error which is the difference between current working frequency and the resonance-frequency of the drive mode. By building the frequency closed-loop corresponding to the phase-control loop, we find that the order of the loop-filter is just one when considering loop-filter as a first-order-model, which is different from the general phase locked loop (PLL) that is second-order. Elaborate design of the digital phase-control circuit is carried out based on the FPGA platform where a linear phase-detector is applied. Aided by an amplitude control loop, a double-closed-loop drive control circuit is realized. Results show that the drive control loops work precisely.