Reliability analysis of aircraft servo-actuation systems based on the evidential networks with imprecise information

A servo-actuation system is one of the key executing subsystems of the flight control system of an aircraft. With the development of the fly-by-wire control systems, the 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 experiment information. In the meantime, the available data is insufficient and imprecise during its product design stage. In this paper, the evidential networks or simply EN are adopted to handle the imprecise probabilities. The formulae of marginal belief mass for series and parallel systems are represented respectively. The basic reliability model and mission reliability model of a three-redundancy servo-actuation system in an aircraft flight control system are analyzed using the EN approach, respectively. The EN manage and quantify the imprecision of the servo-actuation effectively, and propagate the imprecision from the root nodes to the top nodes, which represent system reliability.