Modeling And Flight Control Of The Variable-sweep Aircraft In The Wholemorphing

As a kind of morphing aircraft, variable-sweep aircraft can change the wing area initiatively through the wing’s sweeping, to obtain the optimal aerodynamic shape, so that it can perform different missions or adapt different flight environment. When the sweepback changes in flight, aerodynamic characteristics, the locations of aerodynamic center, the centroid moment of momentum, and the center of gravity alter considerably, which have a great impact on the aircraft dynamics. Hence, the modeling and the stable control of the variable-sweep aircraft is of great importance. In this paper, several aspects of the problems of morphing aircrafts are investigated, including computing the aerodynamic data, establishing the model of the system, analyzing the transition stability and designing the flight control system.Firstly, using the Digital DATCOM software to compute the aerodynamic data of the aircraft with a vary sweepback, and the function in aerodynamic data and variation of the sweepback has been solved with the help of the curve-fitting algorithm.Secondly, the six degrees of freedom nonlinear dynamics model of variable-sweep aircraft is constructed, and the longitudinal dynamics equations are obtained by decoupling. As the characteristics range significantly while morphing, in order to describe the whole morphing accurately, the T-S modeling ideas are applied to establish T-S fuzzy model, which can provide the basis for subsequent designing of the control law. Moreover, the accuracy of the T-S model is verified by comparing the simulated results of the T-S model and the nonlinear model.Finally, the longitudinal flight control law of the variable-sweep aircraft is designed. In order to ensure the stability of whole process of morphing, the design and stability analysis of T-S fuzzy control systems are researched by applying the parallel distributed compensation(PDC). Moreover, this paper presents a model reference adaptive control method based on T-S model. By simulating the two controllers, the results show that the aircraft is stable and has a good flying quality in all wing configurations as well as the whole process of morphing, the latter has some adaptive capacity on the outside interference.