Missile free section ballistic deviation analysis and prediction method considering J2 influence

Abstract

The invention provides a missile free section ballistic deviation analysis and prediction method considering J2 influence, comprising the steps of carrying out decomposition of J2 gravitation vectorsand derivation of a free section ballistic deviation analysis and prediction model, and obtaining expressions of perturbation forces in different coordinate axis directions through decomposition of the J2 gravitation vectors; and according to a state space perturbation theory, substituting the decomposed J2 gravitational vector expressions into an integral solution expression of the trajectory deviation of the free flight section of the missile, and performing integration to obtain a complete analytical expression of each deviation. Compared with other methods in the prior art, the method provided by the invention has the advantages that the calculation time consumption of the method is 10-5s, the calculation error of the position under any shot direction is smaller than 50 meters, the calculation result is represented in an inertial system, and the method can directly participate in missile-borne guidance calculation without extra coordinate conversion.

Description

technical field [0001] The present invention relates to the technical field of flight dynamics, in particular, relates to a 2 Analytical prediction method of ballistic deviation in free-flight segment of missile affected by the term. Background technique [0002] The free flight segment is the longest flight time in the entire flight segment of the ballistic missile, accounting for more than 90% of the total flight time. Due to the high flight altitude, the ballistic missile is mainly affected by the gravitational force of the center of the earth during the free flight period, and its flight trajectory is approximately a part of the elliptical orbit. , its true trajectory will deviate from the standard elliptical orbit. In order to ensure the hitting accuracy of the ballistic missile, it is necessary to quickly predict the ballistic deviation of the free flight segment under perturbed conditions when the engine is shut down. In fact, orbit prediction of extra-atmospheric ...

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Problems solved by technology

The flat root number method works well when used in near-earth satellite orbit prediction, but for sub-orbital prediction problems such as ballistic missile free segment trajectory, the accuracy of this method will drop significantly; the fg series method uses flight time as an independent variable , Taylor expansion is carried out on the standard elliptical trajectory, and on the basis of a certain reasonable approximation, it is deduced that considering J 2 The analytical expression of the term, but this method is only suitable for short-term extrapolation, and cannot be used for the calculation of the free segment of the ballistic missile; the non-orthogonal decomposition method is proposed by Chinese scholar Li Lianzhong in 1982 to consider the earth J 2 The analytical calculation method of the ballistic trajectory of the free segment of the missile perturbed has been applied to consider the J 2 In the closed-loop guidance online compensation method affected by the term, but this method cannot guarantee that the accuracy of any downward trajectory prediction is less than 100 meters; the adaptive variable step size numerical integration method is currently the most common method for accurate trajectory prediction. The step size can greatly improve the efficiency of traditional fixed-step orbit numerical integration, but under the condition that the guidance period of the ballistic missile is usually less than 20ms, it is still necessary to study the analytical algorithm with higher precision

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