Research On Aerodynamic Parameter Identification For Projectiles And Rockets Based On Measurement In A Closed Series

In the course of flghting,the projectiles and rockets' trajectory might be disturbed bymany different factors,and the aerodynamic force is one of the important factors to determine the trajectory of the flight.The effects of aerodynamic force can be described by aerodynamic parameters,which determine the trajectory and stability of the projectiles,and it is also an important research topic in the field of compiling firing table and projectiles' flight control.In the shooting experiment,the basic flight date of the projectiles can be measured with the GPS satellite and geomagnetic measuring devices and other equipment,but the aerodynamic parameters can not be directly obtain.In the wind tunnel test,aerodynamic parameters can be directly measured,however,the wind tunnel test can not simulate the actual flight environment completely,the measurement error is large,which can not meet requirement of engineering demands.In this paper,we mainly study the aerodynamic parameters identification of projectiles and rockets which based on flight data and accurate methods of identification.Force and torque are studied when projectiles flying,and the 6DOF ballistics model is established as the state equation of the identification system.Several common identificationmethods are analyzed in this paper,meanwhile,Extended Kalman Filter(EKF for short)and Unscented Kalman Filter(UKF for short)are chosen as the method for the aerodynamic identification of the projectiles.There are 6 parameters such as the resistance coefficient,lift coefficient derivative and so on,which selected as the parameters to be identified.The location,velocity and the attitude angle of projectiles are taken as the observations.The identification model is deduced based on those schemes.The design procedures are used to calculate the relation between the parameters and the Mach number.Finally,the identified aerodynamic parameters are used to reconstruct the trajectory and calculate the drop point,and compared with the actual trajectory.The identification results show that when use the projectiles model with 6DOF as the computational model,using EKF can not correctly identify all the parameters,and using UKF can accurately identify those parameters,which result is reliable.The trajectory calculation coincide with the actual trajectory to great extent.The results show the feasibility of the identification method in actual project application.