MULTIPURPOSE APPROACH TO VISUAL NAVIGATION BASED ON LANDSCAPES FOR UAVS OPERATING IN GNSS-UNAVAILABLE CONDITIONS

The aim of the study is to provide the possibility of UAV navigation when it is impossible to use satelliteglobal positioning systems using GNSS in electronic warfare conditions. To achieve this goal, acomprehensive approach to ensuring UAV navigation by visual landmarks using machine vision systems isproposed. It is proposed to synthesize images of the underlying surface by combining sensor data, whichimproves the quality of UAV positioning in the absence of satellite navigation systems. It is shown thatwhen combining remote sensing images of different origin and changing external operating conditions(day-night, winter-summer, etc.), it is important to most fully localize the objects of the underlying surface.In the machine vision system for visual navigation of UAVs by natural landmarks, a method of electromechanicalimage scanning is proposed, which allows increasing the field of view of a camera of an arbitraryrange. Modeling of the characteristics of the machine vision system with electromechanical scanningis carried out to determine the limits of applicability to the problem of visual navigation. It is shown thatthe most significant parameter of positioning accuracy is the shooting height of the underlying surface,which is quasi-linear under the condition of a fixed camera tilt angle, and for high-quality positioning, thebest option is the frontal position of the camera at the nadir point. The proposed approach allows creatingvirtual 3D models of the underlying surface, thereby increasing the capabilities for more accurate recognitionof objects based on the scale and size of the segmented areas. Measuring the camera elevation anglecan be used to detect and recognize natural landmarks that can be predetermined (road intersections buildings or structures, utility facilities, etc.). On the other hand, the frontal position of the camera with azero elevation angle is advantageous for verifying the flight route, positioning the UAV relative to thereference landmark. This is due to the fact that with the widespread use of software based on mathematicalmodels, the photogrammetric ruler technology has become appropriate for quantitative measurementof terrain plans and maps