Research Of Aerodynamic Parameter Identification For Ballistic Correction Rockets

The rocket is flying in the atmosphere,we mainly study its flight trajectory,in which several aerodynamic parameters have the most influence on the trajectory.However,in the shooting experiment,we use the radar,geomagnetic measuring devices and other equipment can only measure the basic data of the rocket,can not directly get these aerodynamic parameters.In the wind tunnel test,we can directly measure the aerodynamic parameters,as well as the scientific theory of the calculation method can be used to obtain these aerodynamic parameters,but the error is larger,can not realistically simulate the flying state of the rockets,can not meet the actual needs.What we need to study in this paper is to identify the aerodynamic parameters of ballistic-modified rockets by parameter identification.The main purpose of our study is to identify the aerodynamic parameters which have a great influence on the outer ballistic trajectory of the rocket from the shooting experiment of the shooting range,using the basic data of the external ballistics measured by various measuring equipment(radar,geomagnetic measuring equipment,etc.).Based on the theory of system identification and optimization,this paper compares three kinds of classical parameter identification methods,and presents the basic method of parameter identification with least squares.Based on the isight parameter optimization software,the four degrees of freedom ballistic equations are deduced according to the identification task and the purpose of this paper,the aerodynamic parameter model suitable for this identification is found out,the 0-liter drag coefficient and the derivative of lift coefficient 10% are chosen as the initial value of the design variable as the objective function identified in this paper,the trajectory residuals are selected by several optimization algorithms which are suitable for the parameter identification,and the 0-liter drag coefficient and the lift coefficient derivative are identified respectively.The simulation results are applied to the engineering practice,the maximum deviation of the calculated trajectory and the measured ballistic data distance is about 38 meters,the maximum deviation of the height is about 30 meters,and the maximum deviation of transverse deviation is about 24 m.The feasibility of the method applied in practical engineering is validated.In the process of the identification of aerodynamic parameters,we should make rapid and accurate identification,so we should pay attention to the interaction of each aerodynamic parameter in the whole outer trajectory,based on Powell method,this paper develops the aerodynamic parameter identification software,which is more perfect,and uses it to recognize the 0-liter drag coefficient and the derivative of lift coefficient,and obtains the comparison of trajectory and trajectory of the measured trajectory and the residual convergence.The identification results show that the standard deviation between the calculated trajectory and the measured trajectory data is about 30 m.The research shows that the aerodynamic parameter identification software is used to calculate the aerodynamic parameters accurately,and can be applied to the actual design of projectile and arrow.