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Nonlinear Dynamic Characteristics Analysis And Control Of Aircraft At High-Angle-of-Attack

Posted on:2008-01-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y L ChenFull Text:PDF
GTID:1102360215497040Subject:Fluid Mechanics
Abstract/Summary:PDF Full Text Request
In conjunction with the strongpoint of both bifurcation analysis methodology and nonlinear control law design methods, an integrative design idea of nonlinear dynamic characteristic analysis and control law design is put forward, several integrative design techniques are established. And these techniques are applied to both the analysis and control of the nonlinear motion phenomena of aircraft at high angle of attack, such as wing rock, inertia coupling, deep stall and spin, and the investigation of the post-stall control law design. The main research work is listed as follows:An integrative method of nonlinear dynamic characteristic analysis and control law design, i.e. BACTM-FLC method, is development by integrating bidurcation analysis with fuzzy logical control. The wing rock of a delta wing is investigated by employed BACTM-FLC method, the global dynamic behavior of the wing rock is shown after the bifurcation analysis, and the wing rock phenomena is suppressed by the fuzzy logical controller successfully.The extended bifurcation analysis(EBA), which is the extension of standard bifurcation analysis, is used to the zero side slip maneuver flight. And then a new integrative design technique, which is called EBA-FLC method and effective to constrained flight analysis, is developed. As an example, the rolling dynamic behavior of a light maneuverable aircraft is investigated. The equilibrium surface and the bifurcation surface at different aileron deflection are caculated and the jump phenomena during the fast rolling is shown. With the open-loop bifurcation control law, which is devised by EBA, the stable zero side slip flight in a range of aileron delfection came true. Based on this, a fuzzy controller is designed, and the dynamic behavior of the zero side slip rolling is improved, the range of stable zero side slip rolling is enlarged, and the maximum roll rate is enhanced.The deep stall characteristic of several"T"tail configuration aircrafts are analyzed using bifurcation analysis, and the deep stall recovery characteristic is reflected clearly. According to the relationship between the system's stability and the positive definiteness of Liapunov function & the stability of the slide mode surface, deep stall recovery control laws are designed with Liapunov method and slide mode control respectively, and their principle of work is discussed.The mathematical modal of aircraft with vectoring thrust is established and the aerodynamic modal of an advanced fighter is given. A nonlinear flight control law is designed with singular perturbation theory and dynamic inversion method, and the general aerodynamic deflection and the thrust deflection is alloted by weighted least squre method.The spin characteristic of an advanced fighter aircraft is shown clearly after the bifurcation analysis, and according to that the nonlinear dynamic inversion(NDI) method can make a simple linear system out of a nonlinear system by states feedback global linearization, the NDI method is employed to design the spin recovery control law, and the oscillatory stable flat spin recovery is achieved successfully.In order to reflect the nonlinear dynamic behavor of aircraft at high-angle-of-attack and the effectiveness of the control law, the numerical simulation of four typical post-stall maneuvers is done with the NDI method at the end of this paper.
Keywords/Search Tags:nonlinear system, bifurcation analysis, wing rock, inertia coupling, deep stall, spin, trajectory optimization, post stall maneuver, fuzzy logic control, slide model control, nonlinear dynamic inverse, thrust vectoring control
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