An Operation and Mechanization of the Hemispherical Resonator Gyroscope
Anthony Matthews, Retired
Location: Big Sur
The Hemispherical Resonator Gyro (HRG) is unique in the area of High accuracy inertial sensors. One of its very first applications was on the Cassini mission to Saturn, its Rings, and its Moons. Since that time it has been the chosen gyro technology for precision space missions both military, and commercial. For these missions the HRG has been mechanized to operate in the Whole Angle (WA) mode where operation under high dynamic rates is required. When high sensitivity and very precise angular measurements are a premium the same HRG can be switched to a Force To Rebalance (FTR) mode. In the FTR mode the gyro operates at low rates thus sacrificing the inherent high rate capability of the HRG.
It should be noted that a third mode can be mechanized that gives the same high rate capability as the WA mode and at the same time capable of the precision that is achieved in the FTR mode. This mode is known as the Whole Angle Tracking (WAT) mode. To implement this mode changes to electronics that are responsible for the readout and control of the gyro are required. This paper will outline these mechanization changes and also show a reduction in the electronics that support the mechanical assembly that is the HRG. Because electronic noise characteristic plays a very large role in the sensitivy of the gyro, a reduction of these the electronics should lead to an improvement of the noise characteristics of the complete HRG package. Mechanization of this WAT mode is presented together with simulation of the mechanization that demonstrate both the high rate and high precision sensitivity of the gyroscope. It should be noted that this mode was actually implemented and tested when exposed to laboratory conditions.
Finally, D.D Lynch plainly demonstrated in one of his paper that “size does matter” in the quest for high precision using HRG technology. Accordingly this paper will outline geometry of a HRG that is very competitive with that used in HRG applications today, but at greatly reduced production costs .This technique, “glass blowing” and, or “glass moldings” is being activity pursued in many establishments