Downward trendline bunching SAR radar positioning method based on imaging matching

Abstract

The invention discloses a downward trendline bunching SAR radar positioning method based on imaging matching. The method includes the steps: taking a ground point target as an original point, establishing a geometrical configuration of missile location in an East-North-Up coordinate system on the basis of a downward trendline of SAR radar, and sequentially obtaining an SAR imaging plane image of the ground point target on an imaging plane and the actual position A of SAR radar; obtaining an SAR imaging matched image by means of a geometrical distortion correction mapping function between the imaging plane and a ground plane; obtaining P matching points through an image matching algorithm, and obtaining an affine transformation matrix between the SAR imaging matched image and a set SAR imaging reference image according to the P matching points; constructing an Euler tetrahedron by means of the affine transformation matrix; and according to the set sampling frequency and distance unit numbers of the SAR radar, obtaining the distance between the SAR radar and the ground point target T, the distance between the SAR radar and a set reference point C and the distance between the SAR radar and the p matching point Pp, and calculating the coordinate value of the actual position A of the SAR radar.

Description

technical field [0001] The invention belongs to the technical field of radar image target positioning, in particular to a descending orbit spotlight SAR radar positioning method based on image matching, which is suitable for providing accurate position information for missile body deviation correction. Background technique [0002] In the terminal guidance stage of the missile, due to inertial navigation error, there is a large deviation between the actual position of the missile body and the position indicated by the inertial navigation, which affects the accurate positioning of the missile seeker to the target and cannot meet the traditional optical missile seeker. The accuracy requirement of shift change reduces the precision strike performance of the missile. The missile-borne synthetic aperture radar (Synthetic Aperture Radar, SAR) seeker adopts the spotlight SAR imaging mode in the descending section of the missile. The SAR reference image is matched and positioned to...

AI Technical Summary

Problems solved by technology

[0003] Yanying et al. mentioned the SAR platform positioning method based on inertial navigation data in the document "Missile-borne synthetic aperture radar imaging processing and positioning error analysis". Although the method is simple, the error of the inertial navigation data used in China is generally large, resulting in low positioning accuracy of the SAR platform

[0004] Li Yachao and others mentioned in the document "Milestone Positioning Method and Analysis in SAR Terminal Guidance" that using three different fixed target scenarios in the terminal guidance of missiles and the known slant distance and ground distance of the three fixed target scenarios The parameters are used to locate the missile body; although this method analyzes the influence of missile regular flight and missile irregular flight on the positioning accuracy, this positioning method is only applicable to the situation where the SAR platform works in the frontal and side-looking strip mode. For large squint Spotlight mode, this method does not apply

[0005] Li Yachao and others mentioned a squint SAR platform positioning algorithm based on scene matching in "Feasibility Research on High-speed SAR Platform Positioning and Velocity Measurement under High-precision Scene Matching". Alignment with the squint SAR platform for positioning and speed measurement; although the positioning accuracy of this method is high, it will still be affected by the position of the ground matching point. When the registration error and estimation error are determined, or the position of the ground matching point is close, the Decreases the positioning accuracy of the squint SAR platform

[0006] Yang Libo and others established a positioning model based on the distance difference and Doppler difference of matching points in "Synthetic Aperture Radar Scene Matching Guided Missile Positioning". The angle between the velocity vector and the center slope distance vector is not on the same plane as the angle between the velocity vector and the instantaneous slope distance vector, that is, the positioning model of distance difference and Doppler difference cannot be used for angle measurement positioning

In addition, when the polar format algorithm (PolarFormat Algorithm, PFA) is used for SAR imaging in spotlight mode, the oblique plane SAR imaging obtained is a two-dimensional wavenumber domain map, which makes the Doppler angle measurement formula unable to be used directly, and also limits the method scope of application

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