Design of restructurable flight control systems using feedback linearization

In this paper, a design method is presented for restructurable flight control systems based on the feedback linearization method. Failures are identified indirectly by estimating parameters of the nonlinear aircraft model using the recursive least square algorithm. The aircraft is assumed to have many control surfaces that can be driven independently. In the design, actuator dynamics are taken into account and the Control distributor, which reduces real inputs to generic inputs, is used. The imaginary actuators for generic inputs are introduced to generate input signals used in parameter identification. Pitch and roll angles are controlled indirectly by controlling pitch and roll rates, respectively, which is an approximate way but makes the control system simpler than applying the feedback linearization method straight to the control of the angles. To evaluate the performance of the restructurable flight control system, two failure cases are simulated on the six-degree-of-freedom nonlinear aircraft model.