Reliability Analysis of Aircraft Servo-Actuation Systems Using Evidential Networks

Servo-actuation system is one of the key executing subsystems of the flight control system of an aircraft. With the development of fly-by-wire control systems, redundant servo-actuation systems have been extensively applied. A servo-actuation system has a long life and high reliability, which results in the lack of failure information. In the mean time, available data is insufficient and imprecise during its design stage. In this paper, evidential networks (EN) are used to handle imprecise probabilities. The formulae of marginal belief mass for series system, parallel system, series-parallel system and parallel-series system are represented respectively. The basic reliability model and the mission reliability model of a three-redundancy servo-actuation system in an aircraft flight control system are analyzed using EN approach, respectively. The EN manage and quantify the imprecision of the servo-actuation effectively, and propagate imprecision from the root nodes to the top nodes representing the system reliability.