The Method Of Uncertainty Quantification Of Flight Vehical Guidance And Control System

The current evaluation method of guidance and control system generally only considers the design of the deterministic scenario,neglecting the uncertain factors that are unpredictable in real life,such as the lack of personnel knowledge,the variability of the system operating environment,and so on.It can cause great impact and even unexpected failure.Therefore,this paper studies the object of guidance and control system of flight vehicle with uncertain parameters.A set of research method to solve the uncertainty quantization of the guidance and control system of aircraft is analyzed from the aspects of parameter calibration,uncertainty propagation of approximate model and sensitivity analysis.The main research work of this paper is as follows:First,the six freedom degree of flight vehicle is modeled in view of the characteristics and requirements.At the same time,the uncertainty parameters such as aerodynamic coefficients are determined by referencing the opinion of experts.The whole research framework of uncertainty quantification is constructed and statistical characteristics of the output indicators before quantification is given for the foundation of further research.Second,the calibration problem of uncertainty parameters in uncertainty quantification is studied.A K-S parameter calibration method of genetic algorithm is proposed based on the thought of K-S test.By comparing the cumulative probability density function of the real situation and the simulation situation,the optimal solution of epistemic uncertainty can be found through the genetic algorithm optimization process.In order to make the uncertainty system described by the simulation mathematical model reflect the real situation more accurately,the rationality and effectiveness of the method are proved by an example of a launch vehicle.Third,the problem of uncertainty propagation and sensitivity analysis in uncertainty quantification is studied.Not only the statistical quantization of the input parameters' uncertainty propagation to the output response is considered,but also the effect of various uncertainty input parameters on the output of the system is considered.The polynomial chaos expansion method is used as an approximate model to replace the complex original model to reduce the amount of calculation considering the many uncertain parameters and the complex structure of the model.Based on the approximate model,the global sensitivity analysis based on variance is used to quantitatively describe the influence level of the uncertainty parameters.The propagation analysis of the launch vehicle's ascending section is carried out in an example to verify the correctness and practicability of the proposed method.Finally,the uncertainty quantification tool for the guidance and control system of flight vehicle is developed.Through requirement analysis and development process design,a step framework for design tools is proposed.And modular design is carried out in the VS2010 environment according to the framework process steps.An uncertainty quantification tool is used to analyze the ascending phase of the launch vehicle,which verifies the operability of the tool.