Identification of Gain Mismatches in Control Electronics of Rate Integrating CVGs

Abstract

In Coriolis Vibratory Rate Integrating Gyroscopes (CVRIG), accuracy of angle measurement is known to be coupled to symmetry of the mechanical structure. This paper provides a study on the effect of asymmetries in control electronics on operation and accuracy of direct angle measurements. We demonstrated that gain mismatch in detection electronics affects the estimation of the pendulum variables in the CVRIG mathematical model. An error in the pendulum variables was shown to adversely affect the estimated orientation of the orbital trajectory and the closed-loop control. In the case of gain mismatch in actuation electronics, the control forces were observed to interfere with free precession of the oscillation pattern causing additional errors in the angle measurement. We proposed a method to distinguish the angle errors due to mechanical asymmetries from the angle errors caused by imperfections in control electronics. Using the method, we identified gain mismatches in the control electronics and subsequently used the identified parameters for calibration of a micro-fabricated gyroscope. By applying the method of calibration to a Dual Foucault Pendulum (DFP) gyroscope, we were able to reduce the angle bias error by 10-times and reached a 0.06 degree of precession accuracy at the input angular rate of 500 dps, without any compensation for mechanical asymmetries.