Research On Aerodynamic Parameter Identification Method Of High Speed Rotating Projectile Based On Maximum Likelihood Method

In this dissertation,the method of aerodynamic parameter identification based on the maximum likelihood method is studied.And the method is used in the application to the identification of the resistance coefficient of the high speed rotating projectile.In this thesis,the revised six degree of freedom trajectory model are chosen for high spinning projectile.Then the UKF is used to process the projectile data measured by radar,then the optimal estimated data is obtained.Due to the maximum likelihood criterion and Newton iterative algorithm are most widely used and common for system identification,this paper combining high speed rotating projectile model,and deriving the maximum likelihood identification criterion and corresponding Newton iterative formula which requires the derivation of sensitivity equations,at the same time,the sensitivity is analyzed,it is shown that the sensitivity of the resistance coefficient versus speed is very high,which means the speed is suitable for the identification of resistance coefficient.Finally,according to mathematic model,identification criterion,Newton iteration method and four order Runge Kutta method,coding and debugging the resistance coefficient identification program under VS 2010,the aerodynamic coefficients of high speed rotation projectile are obtained.A projectile track can be obtained when the identified resistance coefficient is put into the mathematic model.Comparing the track with the radar result,it is shown that the identified resistance has revised the wind tunnel result,and can get even closer to the radar result.Therefore this method studied in this paper can get the resistance coefficient effectively from free flight data,and can provide some reference value for aerodynamic parameter identification of projectile and other aircraft.The aerodynamic parameters deterrmine the.trajectory and stability of the missile,and it is also an important research topic in the field of missile flight control.Through the free flight test data of projectile can identified aerodynamic parameters which can meet the aerodynamic characteristics of high speed rotating projectile better.Therefore it is of great reference value for making firing table and designing the control parameters of the projectile.