Research On Two-dimensional Trajectory Correction Technology For Spin-stabilized Projectile

As one of the important developing direction of smart ammunition technology.Two-dimensional trajectory correction fuze is of great significance in improving the projectile firing accuracy,decreasing the collateral damage and reducing the logistical support.Based on square-crossing fixed-cant canard configuration of 155 mm spin-stabilized projectile,study of six degreees of freedom(6-DOF)ballistics modeling under controlled conditions,ballistic response characteristic analysis,projectile flight stability analysis,impact point prediction and trajectory correction strategy are carried out.Specific works are as follows:(1)Based on the analyises of projectile's motion feature,6-DOF ballistics model under the control of cross-fixed cant canard is biulted.Uncontrolled and open-loop controlled trajectory simulations are carried out for 155 mm spin stablized projectile.The relationship between canard force and the correction capability of the projectile point,and relationship between the canard rolling angle and the correction angle of impact point have been provided.(2)6-DOF ballistics model is hard to apply for real-time calculation and without projectile attitude for high spin and overload,the 6-DOF model is linearized using the perturbation method,and then the ballistic response analytical expression after a short time is simplified using the perturbation method.On this basis,a method for calculating canard rolling angle control command by using the ballistic deflection without the projectile pitch and yaw attitude is carried out.The results show that error is less than 5° between the rolling angle calculated by simplified ballistic response analytical expression and the numerical results calculated by the 6-DOF model.(3)To acquire an efficient trajectory correction ability with flight stability.On the basis of the angular motion research,stability criterion of Gyroscopic Stability,dynamic stability and following stability for 2D trajectory correction of spinning-stabilized projectile are given.The geometry of cross-fixed canards configuration for large diameter spinning-stabilized projectile is designed using Missile DATCOM combining with stability criterion,then CFD numerical calculations and wind tunnel tests for this configuration are carried out,to research the aerodynamic characteristics and correction ability.The results show that,range correction ability is not less than 2.3%,lateral correction ability is not less than 7.9%,and the stability criterions are all satisfied.(4)Considering impact point prediction based on the model of modified point mass(MPM)shows large error under big elevation.Error mechanism of MPM model for this problem is analyze,and the angle of attack error compensation method which improving the prediction accuracy of MPM model is propose.The extended Kalman filter is designed,so the estimated value of the trajectory parameters and the error compensation coefficients can be obtained via optimal estimation theory,finally the hardware-in-the-loop simulation experiment is carried out.Results show that,under the condition of maximum range,error compensation MPM model can meet the accuracy requirements,which is that longitudinal error is not more than 48 m and the crossrange error is no more than 15 m,32 seconds after the projectile is launched.(5)The correction interval for correction law is determined by the time of ballistic response,with considerations of the response delay of canard actuator and projectile body.The constraints of proportional correction law are obtained from the study of its motion rules.On above basis,impact point prediction & proportional correction combined correction law is proposed.Taking the 155 mm spin-stabilized projectile for instance,the ballistic simulation of close-loop trajectory correction under ideal conditions and the Monte Carlo simulation with meteorological conditions are carried out,using impact point prediction(IPP),trajectory track(TT)and combined correction law separately.Results show that,the CEP of uncontrolled projectile is 353.4m.The CEP of combined correction law is 36.6m,which is better than the IPP and TT correction law.