Research On Robust Adaptive Coordinative Control For Near Space Vehicle

As near space vehicle (NSV) is one of the most important crafts for space exploration andmilitary defense, the research work on it deserve profound significance. Due to the requirements offlight tasks and the limit of flight environments, NSV with hypersonic velocity possesses somedistinct characters, such as serious nonlinearity, fast time variation, intense coupling and stronguncertainty. Therefore, it is a great challenge to design a flight control system for NSV. Consider thischallenging problem, some work such as modeling, coordinative control idea analysis, and nonlinearrobust adaptive control design are proposed in this dissertation.Firstly, based on the analysis of hypersonic flow characteristic and features of atmosphere in nearspace, the dynamic forces of NSV are systematically analyzed and then a set of six-degree-of-freedom twelve-state equations are derived to describe the motion of NSV in variational wind field.After that, the open-loop control characteristics under different conditions are studied by simulationanalysis. It is demonstrated that the characteristics of the developed model, such as seriousnonlinearity, fast time variance, intense coupling and strong uncertainty.Based on the modeling work, the coordinate control problems are presented as the key work ofthis dissertation to be implied for nonlinear controller design and robust adaptive controller design,listed as following.I. Attitude coordinative controller design methos is raised firstly to track the attitides of NSV andthe so called NGPC (nonlinear generalized predictive control) method is employed into the nonlinearcontroller design. The theoretical analysis and simulation results show the good optimizationperformance of this method.After thet, the SMDO-based (sliding mode disturbance observer) NGPC control strategy andonline-SVR-based (support vector regression) NGPC control strategy are employed to realize therobust adaptive coordinative control for attitude motion of NSV. The stability of each closed-loopsystem is analyzed via Lyapunov method and the excellent control performance is demonstrated bysimulation.II. Based on the clou of airframe/engine integration design, the coordinate control methodintegrating aerodynamic control surfaces and thrust of engine are proposed to track the longitudinaltrajectory. The SGPC (sliding-mode generalized predictive control) control strategy is employed todesign the controller for nominal system. Theorical derivation and simulation analysis demonstrate the optimization performance and a little bit robustness of this method.Furthermore, a new online SVR based on finite sample set is proposed to realizeonline-SVR-based SGPC coordinative control for flight/thrust integrated longitudinal motion of NSV.The fuzzy adaptive SGPC is also studied to design the robust coordinative controller for longitudinalmotion of NSV. Lapunov method is used again to analyze the performance of the both closed-loopsystems, and the simulation results show the satisfying robustness of these two adaptive controlmethods.III. The design method of attitude-trajectory coordinate control system is proposed based on theidea of hierarchical control. The NGPC method and the improved SMDO are employed to design thenonlinear controllers and robust adaptive controllers for each loop of this system, and the controlperformance is demonstrated via systematically analysis and simulation verification. It can stablytrack the longitudinal trajectory with smooth and steady attitudes.Finally, the work of this dissertation is summarized and the further work is also discussed.