Loose Coupled Initialization Method for Visual Inertial Navigation in Outdoor Low Altitude Flight Environment

In the outdoor low altitude flight environment, the inertial navigation self-alignment initialization method is difficult to apply to the dynamic environment, since the non-autonomous alignment method is not accurate in the case with large misalignment angles, and the method of using visual-information-assisted inertial navigation system initialization relies on the horizon extraction algorithm or the advance deployment of artificial landmarks, which is not flexible enough. To solve the problems above, a loose coupled inertial navigation system initialization method is proposed aided by visual information. First, the feature points are segmented into sky end and ground end at the vision front end. And the camera poses in the camera coordinate system are calculated using the visual structure from motion. Then the camera poses and the re-integration of acceleration and angular velocity measurements are aligned to obtain the initialized poses. The performance of our algorithm is verified by performing a low altitude flight simulation in three cases with a semi-physical simulation system.