| The guidance system's performance is a key factor affecting the operational effectiveness of strategic missiles.Constantly improving the accuracy and adaptability to large deviations of the missile guidance system is the fundamental way to meet the requirement of high-precision hit for the current maneuverable launched strategic missiles.Taking this as a goal,this paper studies the fast prediction method of trajectory error considering the perturbations and the real-time compensation method of guidance.The main work and conclusions are as follows:First,two unified analysis models for error propagation of boosting phase of missile for different application requirements are proposed.Aiming at the problems of the current boosting segment error propagation model considering the single perturbation factor and the incomplete analysis of the influence mechanism of partial perturbation,the premise,cause and propagation mechanism of each perturbation factor are carefully combed.According to the difference of the reference datum,the error propagation perturbation equation based on the dynamic standard trajectory and the error propagation perturbation equation based on the navigation standard trajectory are constructed respectively,which can be used to comprehensively analyze the landing point error and initial velocity error of the launch point,Gravity model error,missile body and environmental parameter error,inertial guidance tool error and other effects on ballistics.The advantages and disadvantages of the two methods of error propagation characteristics analysis are discussed in detail.The applicable scope of each method is clarified,and the error propagation theory of boosting segment is further enriched and improved.Compared with the numerical integration method,the calculation accuracy of both types of error propagation models is better than 3.5%,and the calculation efficiency is more than 80 times of the difference method.Second,The perturbation equation for the free flight segment of strategic missiles is constructed based on the state space perturbation method.In the orbital column coordinate system,the precise dynamic differential equation of the free segment of the strategic missile with the true near point angle as the independent variable is established.The derivation process of the space perturbation equation of the free segment of the strategic missile and the state state based on the variable displacement are introduced in detail.Matrix solving process.Based on the Lagrangian coefficient,another derivation method of the state transition matrix of the perturbation equation is proposed.Compared with the variable displacement method,the method does not need to solve the high-dimensional perturbation differential equation.The derivation process is simpler and easier to change.The high-dimensional state transition tensor is expanded.The simulation analysis shows that the state transition matrix proposed in this paper is more accurate than the Battin method in solving the initial error propagation problem of the ballistic free segment.Third,an analytic solution of missile's motion for the free flight segment perturbed by the J2 term gravity is proposed.Based on the pole-point transformation method,the expressions of the gravitational potential and gravitational vector of J2 in the orbital column coordinate system are derived.Then,two methods of analytic solution of ballistic deviation affected by J2 are proposed,namely direct integration method and potential function method.The former derivation process is relatively simple,and as long as the perturbation can be expressed as an independent variable function,the analytical solution can be derived according to the derivation of the method;the latter simplifies the expression of the analytical solution to some extent by introducing the J2 term gravitational potential function.But the requirement for the power must be conservative.On the basis of the direct integration method,the second-order correction model of the ballistic deviation analysis and prediction caused by the gravitation of J2 is further deduced,and the calculation accuracy of the first-order model is doubled at the cost of loss of certain computational efficiency.In the strategic missile ballistic deviation prediction problem,the calculation accuracy of the first-order solution of J2 term is one order of magnitude higher than that of the flat root number method,and the computational efficiency is 9.6 times that of the adaptive variable step size numerical integration method(RKF method).The second-order correction solution The calculation efficiency is 1.7 times that of the RKF method.Fourth,an analytic solution of missile's motion for the free flight segment perturbed by the disturbing gravity is proposed.To derive the free-body ballistic analytical solution affected by any order of disturbance gravitation,in principle,the high-order spherical harmonic function needs to be brought into the free-range error propagation perturbation equation for direct integration.In order to avoid the difficulty of directly integrating the high-order spherical harmonic function,the paper uses the disturbance gravitational reconstruction model along the flight trajectory to approximate the true disturbance gravitational vector of the free segment of the strategic missile.Based on the Lagrange spatial interpolation theory,the interpolation polynomial of the disturbance gravitation is derived,and then the interpolation is performed.The polynomial is integrated into the free-range error propagation perturbation equation of the strategic missile,and the free-form ballistic deviation analytical prediction model influenced by any order disturbance gravitation is derived.The simulation analysis results show that the calculation efficiency of the analytical model is more than 300 times higher than that of the RKF numerical method under the condition of the 72×72-order disturbance gravitation model,and the maximum residual value of the terminal position calculation is not more than 5 meters.Finally,the real-time compensation method for the Closed-loop guidance algorithm is proposed.Based on the analysis algorithm of the free-segment ballistic deviation of strategic missiles under the action of arbitrary gravity,two online compensation strategies for strategic missile closed-circuit guidance are proposed,which improves the existing closed-circuit guidance ground compensation method.The problem of poor stickiness.The essence of the two compensation strategies is to correct the influence of the free-stage perturbation factor on the state of the ballistic terminal by correcting the required velocity vector.The difference is that the first method directly solves the correction vector requiring velocity through the perturbation equation state transition matrix.The second method achieves the purpose of correcting the required speed by calculating the position of the virtual target point in real time.The simulation analysis results show that compared with the ground element compensation method,the two online compensation methods can adapt to the large-scale deformation of the ballistics,and can still guarantee higher compensation accuracy under large deviation interference.The work of the thesis has important reference value for deepening the understanding of the mechanism of ballistic error propagation of strategic missiles,analyzing the influence characteristics of different perturbation factors on strategic missiles,and correcting the influence of perturbation factors on closed-loop guidance of strategic missiles,which can provide theoretical basis and method support for further improving the rapid maneuvering launching capability and high hit capability of our country's strategic missiles. |
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