Innovative Mechanizations to Optimize Inertial Sensors for High or Low Rate Operations

摘要

It is highly desirable for a space gyro to provide excellent performance over a range of dynamic conditions; that is, to operate at both low-rate and high-rate operations. Today Litton's hemispherical resonator gyro is mechanized to perform accurately under low-rate spacecraft operations (<10deg/s). To accomplish this, the sensors in the Space Inertial Reference Unit (SIRU) are mechanized in a closed-loop fashion, referred to as force-to-rebalance. Now with the recent innovation of an open-loop mechanization referred to as whole-angle tracking, the HRG sensor can provide the same excellent performance under high rate operations (>300deg/s). An alternative, open-loop mechanization known as whole-angle mode has been used previously in successful demonstrations of the HRG's applicability to aircraft navigation and missile guidance. Most recently, an innovative mechanization which combines the scale-factor and dynamic range performance of the whole-angle technique with the noise performance advantages of force-to-rebalance has been demonstrated. The application of this technique, known as whole-angle tracking, is described in this paper. Many advantages described below are derived from the RF pickoff electronics developed for use in the extreme environment of commercial, geophysical exploration applications. Test results show that a dynamic range of >300deg/s and scale factor accuracy of <10ppm are achieved while maintaining the high-accuracy noise and bias characteristics, enabling the HRG to perform to the requirements of agile pointing spacecraft as well as directional drilling systems. Product development using this whole-angle-tracking mechanization is sponsored by the US Government for special spacecraft applications and by a commercial firm for geophysical exploration applications.