A method of improving the anti-rudder beating of Si micromechanical gyro driven by rotating carrier

Abstract

The Si micromechanical gyro driven by rotating carrier is a new kind of MEMS gyro. Since it has no a driving structure itself, it differs from the conventional Coriolis vibratory gyro. The gyro is installed on a rotating aircraft and utilizes the spinning of the carrier as a driving. Its sensing output is a amplitude-modulated signal. The amplitude is proportional to the transverse input angular velocity of the carrier, while frequency tunes the spin frequency of the carrier automatically. So the gyro is used for the damping of the single-channel control system of the rotating carrier. The control system uses a pair of the rudder surfaces to control the flight attitude of the carrier. The polar changing of the rudder surfaces will conduct a beating to the body of the carrier. In application, we found that the rudder beating distorts the gyro output signal. Thus the gyro will not work properly and even cause the channel jam of the control system. Aiming at the problem, in this paper we firstly introduce the structural principle and working mechanism of the gyro, and obtain its angular vibrating equation and the solution of the equation by using Euler dynamics equation of the rigid rotating around a fixed point. Then, we analyzed interference of the rudder beating on the gyro output signal in details. The analyses have indicated that the first harmonic of the rudder beating bring the interfering moment since the force arm between the rudder beating and the sensing axis of the gyro exists. Moreover, we tested the resonant frequency of the gyro. The tested result has shown that the second harmonic of the rudder beating is close to the resonant frequency. The situation will cause the resonance of the gyro. In order to improving the ability of anti-rudder beating of the gyro, we putted forward the installed method of 90 ° to eliminate the interfering force arm of the first harmonic. In addition, based on the model of the elastic torsion beams, we increased the thickness of the beams and enlarged the resonant frequency to avoid the resonance of the gyro. Finally, we carried out the experimental validation. The experimental results have demonstrated that the method can effectively suppress the influence of rudder beating on the output signal of the Si micromechanical gyro.