Modeling And Flight Control For Near-space Vehicles With An Oblique Wing

The Near Space Vehicle (NSV) has caused much concern around the world and has become aresearch hot due to its significant features and potential military and civilian dual-use value.Existing NSV usually adopts the configuration with large wing skew angle and low wing span toachieve optimal aerodynamic performance when it is in supersonic flight status. However, suchconfiguration does not take the subsonic and transonic aerodynamic performance into count. Inorder to meet the different requirements for aerodynamic characteristic at low speed and high speedsimultaneously, the concept of oblique wing has attracted increasing attention and research.Therefore, the modeling and flight control for the near space vehicle with an oblique wing(NSVOW) has become an innovative and challenging issue. This dissertation studies the NSVOWmodeling and analysis, and the control of attitude system with uncertainties and input hysteresis,and the control allocation. The main works are as follows:Firstly, a nonlinear flight motion mathematic model of the NSVOW is established. Based onits asymmetry configuration and special aerodynamic characteristic, the six-degree-of freedomequations of flight motion are derived using Newton’s secong law and law of inertia via consideringthe influence of oblique wing. In the dissertation, a more comprehensiv nonlinear model isprovided for the flight control design of NSVOW. Furthermore, an overall design of NSVOW flightcontrol system is presented using the cascade control structure idea. And the attitude modelequations are transformed into the form of affine nonlinear equations respectively.Then, the attitude control scheme is designed for NSVOW with parameter uncertainties andexternal disturbances. A functional link artificial neural network (FLANN) disturbance observer(FLNDO) is designed to approximate the uncertainties and disturbances based on smallcomputational burden characteristic of FLANN, and a FLNDO-based sliding mode control law andFLANN adaptive control law are presented for NSVOW attitude control. The stability ofclosed-loop system is anaylized using Lyapunov method. Simulation results illustrate that goodattitude control performance is obtained under the developed method, and the parametersuncertainty and external disturbance are well suppressed.Following, the attitude control problem is studied for NSVOW with input hysteresis. ABacklash-like hysteresis model is introduced into the aera of input hysteresis for the NSVOW.Through the analysis of this model, the hysteresis is decomposed into a certain linear part and an uncertain nonlinear part with upper limitation. And a sliding mode control law is presented to trackthe desired output trajectory and to eliminate the hysteresis of the system. Furthermore, the prestenedsliding mode control is combined with FLNDO for NSVOW with backlash-like hysteresis anduncertainty. The adaptive law of network weights is derived and can ensure that system errors arebounded. Simulation results show that satisfactory attitude control performance is achieved.Finally, the control allocation scheme is studied for NSVOW. The Sequential least squares (SLS)algorithm is presented based on active set method. The algorithm performance function takes bothactuator position and its change rate into consideration. And the developed algorithm is applied toNSVOW control allocation issue to obation the desired torque distribution and the optimum controlallocation performance. Simulation results demonstrate that the proposed algorithm can achievegood performance.