Research On Scene Matching Navigation Technology Based On Multi-modality Image Matching And Generalized Pseud-range Positioning

While flying,aircrafts often rely on satellites to provide positioning and navigation services,but this method fails in many scenarios.Instead,the airborne Inertial Navigation System(INS)can provide the approximate position information of the aircraft,which is not accurate.On the other hand,airborne Synthetic Aperture Radar(SAR)can operate around the clock and in all weather conditions without interruption to obtain real-time high-resolution ground images.Therefore,for the carrier platform,it is considered to realize accurate positioning of ground objects in the SAR image and then reversely calculate the platform position with it as the control point,that is,to realize scene matching navigation.In combination with radar parameters and related geographic information,through absolute positioning technique we can confirm a rough SAR image geographical scope,then choose the corresponding area of optical map with precise geographic information,and then the real-time SAR image can be matched with it,to accurately calculate the position,of the corresponding feature in the SAR image.In this process,in order to realize the accurate matching,this paper innovatively proposes a new image similarity calculation criterion based on the gray scale mapping matrix,which effectively adapts the gray scale difference between SAR and optical images.After obtaining the accurate positions of ground targets in SAR image,this paper innovatively proposes a platform position solving method based on generalized pseud-range positioning to reverse calculate the platform position.of carrier aircraft.Pseud-range is a basic concept in satellite positioning.It refers to the approximate distance between a satellite and a ground receiver.It is measured by the difference of the clock of the ground receiver.In this study,the slop distance between the platform and the ground target is measured by the time difference between the radar sending and receiving echoes,which can be regarded as the generalized pseud-range between the platform and the ground target.Therefore,a generalized pseud-range observation equation for solving the platform position is proposed in this paper,and the equation is improved under the 6-D INS error model,which effectively improves the positioning accuracy.The experimental results show that this method is feasible and practicable.