Research On The Fundamental Control Problem Of Morphing Aircraft

At present, researches on morphing aircraft have attracted extensive research interests. There are many relative research programs in both America and Europe. Recently, in China, researches on morphing aircraft have also been launched, and many national foundations, such as National Natural Science Foundation of China, start to support this kind of researches. In response to the change of fight environment and missions, a morphing aircraft can change its shape in a continuous, smooth and controlled way, in order to always keep optimal flight status and meet the requirement of enlarging flight envelope and carrying out multi-missions. Compared with traditional fixed-configuration aircraft, the most special part of a morphing aircraft is the shape-change structures with distributed actuators. This dissertation is focused on distributed shape control problems of morphing aircraft, including modeling and control of adaptive ribs with truss structures, dynamic shape control of flexible ribs actuated by smart material, and the realization of a distributively actuated morphing wing experimental platform.First of all, a dynamic model of adaptive ribs with truss structures is constructed. To model the mechanism with complex structures, a lot of coupling constraints, large stroke and highly nonlinearity, two modeling methods are used: the method based on vector mechanics and the method based on analytical mechanics. Both methods acquire the same nonlinear interconnected model of adaptive ribs. Based on this nonlinear interconnected model, by using T-S fuzzy approximation theory, the affine T-S fuzzy interconnected model of adaptive ribs is presented. Simulation results show that the fuzzy model has good approximation performance.Next, the robust control of nonlinear adaptive ribs is studied. Based on T-S fuzzy theory, the decentralized fuzzy controller of adaptive ribs is designed. The bias term of fuzzy controller is designed to transform the affine T-S fuzzy model into homogeneous T-S fuzzy model, which avoids bilinear matrix inequalities. To increase the cooperative capacity of distributed-actuated adaptive ribs, two kinds of performance-guaranteed, distributed cooperative control laws are presented, which are based on neighbor information and virtual structure respectively. Simulation results show that by using the presented controllers, the rib can achieve desired airfoils under external disturbances, and during the control process the rib shape is kept smooth and continuous under the control of cooperative control laws.The next, the dynamic shape control problem of the flexible rib actuated by piezoelectric materials is studied. The airfoil is parameterized, and the distributed parameter model is transformed into a finite-dimensional model. Then, considering the sensor information error caused by residual modes, the observer-based dynamic shape controller and the fuzzy adaptive dynamic shape controller are designed. Simulation results show that the dynamic shape control of flexible rib is realized, the desired shape is achieved, and the rib vibration during the morphing process is slight.Finally, a morphing wing experiment platform with 9 actuating units connected by CAN field bus is developed, and the software for the multiple node sampled control system is designed. The mathematical model of the morphing wing platform is established. Considering the control input constraints in the real system and the dynamic topological structures of the cooperation information links, the distributed cooperative controller based on Consensus algorithm is proposed. The designed controller is implemented on the experiment platform, and experiments are carried out. Simulation and experiment results show that the controller can make all the actuating units cooperatively achieve the desired positions, which demonstrates the feasibility of the distributed control architecture for morphing wings.