Abstract: This paper presents briefly the essential principle of inertial navigation system (INS) by using electrostatically suspended gyroscopes (ESG) and its gimbal structure. Because of the favourable drift characteristics of ESG, the position errors of the above system grow very slowly with time. The discussion focuses on the ESG's drift model and its compensation as well as monitoring in a inertial navigation system. By using gyroscope monitoring with real-time measurements from the redundant axis within the system, a Kalman filter is applied to the above system with effective improvement of INS accuracy. Besides, a constant but unknown drift bias about the redundant axis is estimated accordingly with successful simulation results.

Key words: inertial navigation, gyroscope drift, gyroscope monitoring, Kalman filter