ABSTRACT
In aerospace engineering studies, the practice of flight control is a systems discipline. Understanding of the feedback control/systems approach is vital to understanding the flight control theory and practice of piloted, remotely piloted, or even autonomous atmospheric vehicles; viz. fly-by-wire (FBW) aircraft, missiles, rotorcraft, unmanned aerial vehicles (UAVs) , and micro-mini aerial vehicles (MAVs). Even the Wright brothers had appreciation for 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 a desirable way and recognized the need of 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 briefly discussed in this chapter. Applications of the control theory to aerospace (leading to flight control) span four major areas: flight planning, navigation, guidance, and control. In order to build a satisfactory control strategy, adequate mathematical models of the dynamic system to be controlled are required. The control strategy is that of the “feedback” from the output (or/and any inner state) variable to the input variable (added to the pilot input command), and 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. So, first, we discuss some fundamental aspects and concepts of control in next few sections. Then, we deal with the requirements of control and some control strategies in general. Subsequently, we discuss methods of flight control and related performance evaluation aspects.
