Application of Nonlinear QFT to Flight Control Design for High Angle of AttackManeuvers with Thrust Vectoring

摘要

Nonlinear Quantitative Feedback Theory (QFT) is applied to the design of anflight Control system (FCS) to control maneuvers of an agile aircraft. To do this, maneuvers are chosen that are desirable during within visual range combat. Plant transfer functions are developed through the use of system identification, using the input/output time histories of the maneuvers. During the system identification process the q sub ij(o) are found directly and are constrained to be minimum phase. After identifying the plants, the cascaded multiple-input multiple-output QFT technique is used to design the FCS. During the design of the FCS, stability boundaries are generated through the use of a Matrix sub x program. To prevent the formation of large RHP poles, Gamma-boundaries are developed. Before shaping the loops it is found that FCS scheduling is needed because of large uncertainty in the magnitude and phase of the plants. Because the orders of the designed controllers are too large for the YF-16 simulation program, reduced order controllers are developed through the use of straight line approximations on the Bode plot. After implementing the reduced order controllers in the nonlinear simulation program, problems developed in the modeling process are encountered that prevent the simulation of the FCS's.