Research On Guidance And Control Problem For Near-space Defense Flight Vehicles

As a hotspot in recent years,near space hypersonic flight vehicles have attracted world-wide attention of scientists and obtained rapid development.In this paper,a defense flight vehicle with blended control systems,namely aerodynamic forces and reaction jet control,is designed.With air-launched defense aircrafts regarded as research objective,the guidance and control problems of defense flight vehicles,longitudinal control in the presence of aerodynamic errors,space maneuvering control,and robust guidance and cooperative control problems are analyzed.Control model of the defense flight vehicles with blended control systems is established.First,flight program has been presented,together with coordinate systems and related movement parameters.Then,the aerodynamic design is accomplished,as well aerodynamic model for defense aircraft has been constructed.Finally,the blended control model of the defensive flight vehicles is established.The blended control problem is researched for the near space defense flight vehicles.A finite time based blended control algorithms is deduced to deal with the longitudinal control problem in the presence of aerodynamic errors.In the design process,extended state observers(ESO)are utilized for online estimation and compensation to improve the robustness.Additionally,a new blended control law,together with the allocation strategy is proposed,which mathematically ensures system stability and robustness.Simulations results demonstrate the superiority of the designed blended control algorithms,as well as the feasibility of the integrated design of blended control law with the allocation strategy.The control problems of near space defense flight vehicles are studied.Based on the integrated design of blended control law with allocation strategy,a compound control for space movement has been designed with finite time convergence.ESO is utilized for online estimation.With its output compensating for the external disturbances,stability and robustness of the blended controller is guaranteed.In addition,as the settling time of finite time convergence algorithms depends on initial conditions to a large extent,a sliding mode based blended controller has been designed with fixed convergence time combined with fixed time convergence theories.Simulation results verified the superior performance of the designed controller,where the convergence property is much better than that designed with finite time convergence algorithms.Guidance problems of defense flight vehicles are investigated considering the high maneuvering targets using fuzzy approximation sliding mode control methods.Coefficients of the switching items in the conventional sliding mode guidance law are dependent on target movement,and are closely related to system stability.For defense aircrafts,since the target information is unknown,as a result,the selection of the coefficients of the switching items is difficult.Additionally,the chattering phenomenon when adopting sliding mode based guidance law also influences the guidance performance.Therefore in this paper,range between missile and the target,line of sight angle,which are easily obtained by seeker,are used in the design process.A fuzzy approximation strategy is adopted to estimate the coefficients.Continuous signals are generated to substitute the discrete signals and thus alleviate the chattering problems efficiently.In the end,simulations demonstrate the superiority of the designed guidance law with fuzzy approximation strategy compared to the conventional guidance law.Finally,a cooperative attack guidance law for high maneuvering target aircraft is proposed to deal with the problem of interception probabilities of a single interceptor.Time constraints has been added to the design of conventional sliding mode guidance law.A varying coefficient strategy is adopted to balance the weight between different sliding manifolds,which ensures the defense flight vehicles intercept the targets within the desired time.Simulations demonstrate the effectiveness of the designed method.