Abstract:The hemispherical resonator is a new kind of solid state gyroscope. It has advantages of high precision, small size, long life, low power consumption. The performance of hemispherical resonator gyroscope is determined by the quality factor and the frequency split of the resonator. Therefore, the identification and trimming of the unbalanced mass is quite important. Firstly, six different methods and systems for the identification of the rigid axis location and the unbalanced mass are introduced. The advantages and weaknesses of the six methods are analyzed. Secondly, the balancing theories are summarized. The status and the characteristic of mechanical balancing, chemical balancing, laser balancing and ion beam balancing are reviewed. Finally, some comments are made on the balancing technology of the hemispherical resonator.