A Study of Closed System Response in Multiloop Flight Control System Using -1/ξ Locus Method

Abstract

There are many design methods for the multiloop control system, but a method to exactly evaluate the stability margin for multiloop control systems has not been established yet. It is very important for the designers to exactly know the stability margin of the flight control system, because it directly comes to bear on flight safety. Previous research has proposed the “-1/ξ locus” analysis method for the exact evaluation of the stability margin of multiloop flight control systems. -1/ξ is an open loop transfer function of multiloop control systems that is considered as an extension of that for single-loop control systems. In this paper, the relation between the response of the closed loop and the stability margin is considered by using the -1/ξ locus. Lateral-directional flight control system was taken for instance, important points to pay attention to use the -1/ξ locus method for designing the flight control system are presented.