An adaptive fault-tolerant FCS for a large transport aircraft

The final design of the flight control system with fault-tolerant characteristics is shown in Fig. 9.1. Such an FCS is made-up of several parts, first of all the robust control laws that represent the core module of the controller, then a control allocation module which has the capability of distributing the control effort depending on the availability of the actuation devices, whose efficiency condition is given by the Fault-Detection and Identification module. The FDI module also gives information about the aircraft's general behaviour and efficiency, thus allowing a supervisor module to manage the FCS in terms of estimated envelope protection, in addition to the attitude and rate limitations. Finally, an autopilot module, whose mode is selected by the panel, gives the attitude reference to the robust control law module for the aircraft state regulation. The current state of the research in CIRA in the field of fault-tolerant flight control systems is focused on how to achieve robustness against actuator faults by means of adaptive control techniques. While this topic and the control allocation are already well assessed, the FDI techniques represent the next step forward towards the final design. In this chapter, the core module involving the robust control laws is described and reported in detail, along with some descriptions of the autopilot module. The control module is based on the adaptive model-following technique, while the latter is designed by means of the classical sequential loop closure approach. The FCS is the main focus of this chapter and is depicted in Fig. 9.2. Its theoretical background is recalled in the next section. © 2010 Springer-Verlag Berlin Heidelberg.