A Threshold Design Method of Aircraft Sensor Fault Detection Monitor

Abstract

A design method is proposed based on probability and statistics to solve the issue that the contradiction between false alarm rate and missed detection rate of sensor comparing monitor threshold definition. The sensor tracking error probability density function is deduced based on the probability, the false alarm rate and missed detection rate are calculated based on the different monitor threshold. Then a criterion is provided in according with sensor failure rate, aircraft dispatch reliability and monitor failure rate. In order to verify it, a quad redundant rate gyro used on aircraft is analysed and an advanced comparing monitor threshold is calculated. Comparing with the original threshold, the monitor coverage rate with the new threshold is increased 1.42 times than the original one. The actual flight date is researched to verify that the monitor failure rate reach to the minimum value 3.91*10-07/Fh which decrease one order of magnitude comparing with the original one 3.5*10-06/Fh. It could be verified that this method could achieve the balance between the safety and dispatch reliability requirement.