On Fly-by-Wire Control System and statistical analysis of system performance

Abstract

The flight control system proposed for future Boeing commercial airplanes is a Fly-By-Wire (FBW) system. The entirely electronic FBW system will replace the mechanical cable/quadrant/pushrod system used on earlier airplanes. The FB W system, also called an Electronic Flight Control System (EFCS), must meet extremely high standards of integrity and reliabil ity. The heart of the FBW concept is the use of redundant, dissimilar computing and communication channels.

Predicting the performance of such a system is beyond the capabilities of conventional simulation and control system design methods. Moreover, the number of independent, random parameters in the system makes straight forward Monte Carlo analysis prohibitively expensive. This paper describes the simulation methods used to model the EFCS, and the use of statistically designed experiments to extract more infor mation about the performance of the EFCS with a smaller number of simulation runs than is possible with a less structured approach. The results of the analysis defined the performance of the EFCS, especially the tails of the distribu tions of the performance measures, with much greater confidence than could have been gained by more conventional methods.

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