Model reference adaptive control of systems under actuator and dynamics failures with application to aircraft flight control

Structural uncertainties caused by system failures can severely deteriorate control system performance. If not properly compensated, system failures can lead to serious performance deterioration or even disasters in performance-critical applications, such as aircraft control systems. System failures, including actuator failures and structural damage, are commonly seen in modern control systems along with their increasingly large scale and complexity. These failures are usually uncertain in time instants of the occurrence and their amounts, and it can be time-consuming, and sometimes impossible, to accurately measure the failures after their occurrence. Thus effective compensation of such uncertain failures is of both significant theoretical and practical importance. Adaptive control is a suitable choice for the compensation of uncertain failures due to its capacity of accommodating large uncertainties by autonomously updating its controller parameters. This dissertation is to extend the framework of the compensation of the actuator failures and structural damage using model reference adaptive control approach, and to investigate its applications to aircraft flight control systems. The contributions of this study are the modeling study of aircraft under asymmetric actuation failures and damage, the design of new adaptive control schemes for actuator failure and damage compensation and disturbance rejection. The key feature of the developed adaptive control systems is the guarantee of the desired system stability and tracking performance under system uncertainties caused by large structural variations, and the framework of systematic design guidelines for guaranteed performance under system uncertainties with aircraft control applications. Applications of the proposed adaptive control schemes to aircraft flight control are illustrated in extensive simulation studies based on the models of a large transport aircraft and the NASA Generic Transport Model (GTM).