Improved fault detection using a selected grouping of parity equations for advanced flight control systems

Redundant strapdown sensor assemblies (SSAs) are designed to provide greater reliability and survivability for inertial inputs to the aircraft flight control system. Flight control systems frequently use three or more SSAs with voting schemes to choose the best reference. However, the minimum number of SSAs required is two, provided that they are skewed with a transformation between the two systems having only nonzero terms. An improved redundancy management procedure (RMP) is reported that is being used to optimize inputs to the flight control loops, providing cost savings, improved accuracy, and faster fault detection. This procedure diagnoses fault situations faster than conventional parity analysis using a truth table or a look-up table method. This RMP is being implemented and tested on a prototype system that consists of two skewed, low-cost ring laser gyro standard attitude and heading reference systems (RLG SAHRSs), and a mission computer with a MUX for the transfer of information