Analysis Of The Uncertainties Of Hypersonic Vehicle Model And Research On Its Robust Control

Control system design for hypersonic vehicles will be complicated by coupling effects between aerodynamics, propulsion, and structure. Using H∞andμsynthesis techniques, these features can be modeled as uncertainties and incorporated into the design procedure of a flight control system. In the modeling of dynamics of the vehicle, the forces and moments arise from both aerodynamic and propulsive sources, which are for these configurations hard to separate. Hence, analytical expressions are developed to allow for characterization of the vehicle's dynamics early in the design cycle. The method involves a two-dimensional hypersonic aerodynamic analysis utilizing Newtonian theory, coupled with a one-dimensional aero/thermo analysis of the flow in the engine of the vehicle. Also, the paper provides an analytical assessment of the flutter character of the vehicle model. Linear subsonic, supersonic and hypersonic analysis indicates that the vehicle is prone to body-freedom flutter resulting from the decrease in vibration frequency of the all-moveable wing at a high flight dynamic pressure. As the wing-pivot frequency decreases, it couples with the vehicle short-period mode resulting in dynamic instability. A similar instability sometimes occurs when the pivot mode couples with the fuselage-bending mode. In the final, after modeling the uncertainties, use the robust control theory to achieve the performance requirement. At last, apply the mixedμsynthesis to design the controller because of the multiple and mixed real/complex uncertainties.