The invention belongs to the technical field of unmanned aerial vehicle autonomous navigation, and discloses an unmanned aerial vehicle
visual positioning navigation method based on a deep twin network and multi-
modal fusion, and the method comprises the steps: obtaining a real-time
aerial image of an unmanned aerial vehicle and a pre-stored
satellite reference image, carrying out the self-adaptive scale zooming of a
satellite image according to the output height of a
barometer, and obtaining the real-time
aerial image of the unmanned aerial vehicle; eliminating scale difference; the images after scale unification are input into a deep twin network for
feature extraction and matching, and two-dimensional plane transformation parameters between the two images are obtained; and calculating the parameters as initial absolute geographic coordinates, adopting a tight
coupling factor graph optimization frame, fusing a re-projection factor formed by the visual coordinates, an IMU pre-integration factor, a
barometer height factor and a
magnetometer course factor, and estimating and outputting six-degree-of-freedom
pose information of the unmanned aerial vehicle through nonlinear optimization. According to the invention, the problems of poor matching robustness of different-source images and incomplete
pose output in a GNSS denial environment are solved, and high-precision autonomous positioning navigation is realized.