METHOD FOR DETERMINING THE MISALIGNMENT OF OPTICAL-ELECTRONIC AND INERTIAL ORIENTATIONS HELICOPTER SYSTEMS

Abstract

A unique method for determining the misalignment of the orientation of the instrumental coordinate systems of different posts of the optical-electronic system of a helicopter with each other and with an inertial navigation system is proposed. The method does not require preflight preparation, and is based on processing video information streams generated by thermal imaging and television channels of the optical-electronic system, and using information from an inertial navigation system. The method involves the helicopter performing a special maneuver, which is a rotation of the helicopter at a low altitude. This maneuver can be automated. When the helicopter rotates, trajectories of characteristic points of the underlying surface and airfield infrastructure are formed on the images. In general, the trajectories of these points are hyperbolas, which are approximated by straight lines. The parameters of these straight lines are determined using the least squares method. The angle of inclination of straight lines in the screen coordinate system determines the position of the angular velocity vector in the instrument coordinate systems. Since all the posts of the optical-electronic system measure the same vector, it is possible to determine their mismatch in roll between themselves and with the inertial navigation system. Preliminary modeling showed high potentialities of the proposed method. The method can be considered as an integral part of a more general method for coordinating coordinate systems in roll, pitch and course based on processing video streams of optical-electronic systems. When the method is used in real conditions, the errors in estimating the angular misalignment of the optical-electronic and inertial systems of a helicopter can be in units of arc minutes.