Robust simulation model approach to evaluate innovative asymmetry monitoring and control techniques in critical flap failure and aircraft controllability

摘要

Asymmetry limitation requirements between left and right wing flap surfaces are the most important in the design of the actuation of secondary flight control system, both in civil and military aircraft, due to the severity of the consequences. In case the position asymmetry would exceed a defined critical value it must be detected and limited by a dedicated monitoring equipment using a suitable and effective control algorithms. The development of the asymmetry monitoring feature plays a very important role in the design of innovative flap control systems, especially to improve the operating performances of secondary flight control systems installed on board of a modern aircraft. The current monitoring techniques are based on the differential position detection between left and right surfaces and, generally, their application slightly reduces the asymmetry. Nevertheless, in some cases these techniques may have an unreliable behavior in case of torque shaft fracture or major structural failures. When these particular mechanical failures appear special monitoring techniques can improve the control systems performances to overcome the typical shortcomings of the standard methods. In this paper a simulation model is proposed to evaluate, with an acceptable level of accuracy, the real behavior of a standard flap system using different monitoring and control algorithms. A reference control flap architecture, usually applied in military aircraft, is used to validate the model in the same operative conditions. By the proposed simulation model it is possible to evaluate the performances of the asymmetry detection and reduction algorithms with a comparison between different flap control system.