Performance evaluation of stability augmentation system by various Flight Control laws

An insight into the knowledge of Automatic Flight Control Systems (AFCSs) gives an understanding of the basic problem of controlling the aircraft´s flight, and enhance its ability to assess the solutions to the problems which are generally proposed. Before understanding automatic controlling of an aircraft, it is essential to know how an aircraft will respond dynamically to a deliberate movement of its control surfaces, or to an encounter with unexpected and random disturbances of the air through which it is flying. With these thoughts this paper presents a reasonable self-contained account of the most significant method of designing linear control systems which find universal use in AFCSs. This paper being firmly based upon time-domain methods, presents modern methods of control theory, particularly the use of state equations which is a natural and effective technique and harmonizes with the mathematical description of the aircraft dynamics that are most completely and conveniently expressed in terms of a state and an output equation. Also this paper relate to particular modes of an AFCS, being concerned with stability augmentation system which has been implemented for the reference aircraft CHARLIE (a very large, four-engine passenger jet aircraft) at different flight conditions. SIMULINK is proposed to implement SAS´s as they are important to form the innermost loop of an integrated AFCS.