ABSTRACT
The design of an automatic flight control system including a suite of autopilots generally begins with selecting the appropriate desired functions of the autopilots. The next step involves choosing an appropriate control structure from a whole repertoire of such structures that are generally available. These may range from a simple proportional-integral-derivative (PID) controller to a much more complex observer/estimator controller, adaptive or self-tuning controller, internal model controller or even a sophisticated non-linear control structure. The choice depends on the whole range of considerations driven by the functional requirements, safety, stability margins, robustness and handling qualities. The final stage involves choosing an appropriate architecture given that the most modern controller for the large civil aircraft is implemented digitally.
