Effect of time-varying factors on the drift model of Electrostatically Supported Gyro

Time-varying factors are extremely important in both dual-axis servo turntable and Electrostatically Supported Gyro (ESG) by affecting the testing of ESG´s drift model. In this paper, we model four time-varying factors, gyro case mis-alignment angle, installation error between gyro and inner ring platform, turntable base fluctuation, and null position drift of turntable´s angle sensor, as a polynomial of time in the drift model for pole ESG. Based on the kinematic formula of turntable in pole gyro mode, we derive the relationships between the time-varying factors and angles of inner and outer rings of the turntable. Then the cases that these four time-varying factors affect the trajectory of turntable are analyzed term-by-term. We find that the constant drift, gravity-related drift and random drift are greatly affected by these four factors. In the light of these analyses, several basic principles to control these factors are further proposed.