Dual harmonization method and system for a worn head-up display system with a removable attitude inertial device in the cockpit

A dual harmonization method for a worn head-up display system for making the display of piloting information of an aircraft on a display conform with the outside real world,

• the worn head-up display system comprising
• a transparent worn head-up display D0,
• a head posture detection subsystem DDP having a mobile tracking first element D1 securely attached to the transparent display D0, a fixed second element D2 securely linked to the platform of the aircraft, and a means for measuring and determining the relative orientation M12 of the mobile tracking first element D1 relative to a reference frame of the fixed second element D2 linked to the platform,
• an attitude inertial device D3 for supplying the relative attitude M3t of the platform relative to a terrestrial reference frame linked to the Earth, that is removable and that can be securely fixed to the platform on a windshield of the cockpit for any period of operation of the aircraft,
• a harmonization sub-system for the worn head-up display system for making the display of piloting information on the display D0 conform with the outside real world, the harmonization subsystem having a harmonization computer and a human-system interface for managing and performing the implementation of the dual harmonization method,
• the dual harmonization method being wherein it comprises:
• a first step of provision of an augmented inertial equipment item D3p+ securly incorporating, in one and the same assembly, the attitude inertial device D3 of the aircraft, and a camera for taking one or more photos of the outside real world, the camera and the attitude D3 of the aircraft being securely linked;
• a second step of acquisitions of measurements in which a series of an integer number N, greater than or equal to 3, of different sightings Vi are performed, i varying from 1 to N, performed through the semi-transparent display D0, by aligning with the outside real world different images of rank i, denoted by image(i), fixed on said display D0, and each representing one and the same photo, taken before the first sighting V1 by the camera of the augmented inertial equipment item D3p+, seen with a predetermined different angular orientation Oi, expressed in terms of three Euler angles of bearing, pitch and roll, corresponding to a matrix M(image(i)/0) from the reference frame “image(i)” of the image of rank i to the reference frame “0” of the display D0, and in which, for each sighting Vi performed, i varying from 1 to N, the posture detection subsystem DDP measures and determines the corresponding relative orientation {circumflex over (K)}ι of the tracking first element D1 relative to the fixed second element D2, linked to the platform of the aircraft;
• then
• a third step in which the dual harmonization computer jointly computes the matrix of relative orientation M01 between the display D0 in a tilted position and the tracking first element D1 and the matrix of relative orientation M23 between the fixed second element D2 of the posture detection subsystem DDP and the attitude inertial device D3, as respectively, the right matrix {circumflex over (D)} and the left matrix Ĝ, joint solutions of the system of harmonization equations:
• Ûi=Ĝ·{circumflex over (K)}i·{circumflex over (D)}, i varying from 1 to N, in which Ûι is the transpose of the matrix M(image(i)/0).