HRG strapdown navigator

A new technology gyro, the hemispherical resonator gyro (HRG), has been developed which is ideally suited to strapdown navigation systems. The instrument offers greater reliability than current sensors due to its inherent simplicity. A fault-tolerant navigation system has been developed as a technology testbed to exhibit the instrument´s capabilities. A successful flight test program of the system was completed in late 1989. This fault tolerant navigation system is configured with six independent sensor channels consisting of paired gyros and accelerometers. Each sensor channel utilizes a microprocessor, programmed in C, to control sensor readout and compensate for thermal errors. A central navigation processor, programmed in Ada, combines data from the independent sensor channels to provide redundancy management and an optimized navigation solution. A dodecahedron mounting structure for the instrument cluster provides an optimum alignment of the redundant inertial axes. Redundancy management of the sensors is accomplished by an enhanced generalized likelihood test. Key features demonstrated for the HRG navigator are rapid reaction, operation over a wide temperature range, and navigation accuracy