Flight coupling model effect based fuzzy control logic

The influences of coupling in a launch vehicle between longitudinal, yaw and roll channels are more serious in the region of powered or active flight phase. Due to large speed, the effect of undesired roll and yaw angles induced from coupling dynamics may cause fluctuations on the performance of a desired command tracking trajectory in the longitudinal motion. In this study, the moment of inertia and kinematic couplings are considered with two objectives in mind. First is to derive their mathematical models and study their affects on the tracking accuracy of the desired pitch angle command. Second, by applying fuzzy proportional derivative controller design, a significant degradation in the desired command tracking due to simultaneous effect of these two types of coupling can be addressed in comparing to the classical design approach. Linear simulation for a typical launch vehicle is carried out at the end of this paper to demonstrate the objectives of this study.