Reconfiguration and Fuzzy Control Analysis

8.1 INTRODUCTION

In aerospace engineering studies, the practice of flight control is a systems discipline. Understanding of the feedback systems (Appendix C) approach is vital to understand­ing flight control theory and practice of piloted, remotely piloted, or even autonomous atmospheric vehicles (FBW aircraft, missiles, rotorcraft, UAVs, and MAVs). Even the Wright brothers appreciated the fact that the secret to the control of flight was feedback (it could have been a human as a sensor, an actuator, or a controller!). They recognized that the pilot should be able to operate the controls to stabilize, control, and guide the airplane in the desired way and recognized the need for solving the problem of stability and controllability. In fact, they built their ‘‘flyer’’ as a slightly unstable and control­lable one as an engineering experiment. An interesting confluence of theory and practice of automatic feedback control is depicted in Table 8.1 [1]. Applications of control theory to aerospace (leading to flight control) span four major areas [2]: flight planning, navigation, guidance, and control. In order to build a satisfactory control strategy, adequate models of the dynamic system to be controlled are required. The control strategy is that of the ‘‘feedback’’ from the output variable to the input variable (added to the pilot input command). The main idea is that with the information from the output variable, the input variable is suitably altered so that with the new/composite input, the control system’s (e. g., aircraft’s) response comes as close as possible to the desired output. Some fundamental aspects and concepts of control are highlighted in Appendix C. In this chapter the requirements and some control strategies are highlighted and main aspects of fault modeling, analysis, reconfigur­ation, and fuzzy control are discussed from the modeling and analysis point of view.