Dual harmonization method and system for a head-worn display system for making the display of piloting information of an aircraft conform with the outside real world

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

• the head-worn display system comprising:
• a transparent head-worn 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,
• a harmonization subsystem for the head-worn display system for making the display of piloting information on the display D0 conform with the outside real world, the harmonization subsystem having a dual 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 the steps consisting in
• performing a series of an integer number N greater than or equal to 3 of different sightings Vi, i varying from 1 to N, performed through the display D0 by aligning a centred sighting visual pattern on any same fixed target of the outside real world, each sighting Vi corresponding to a different fixed position Pi of the centre of the sighting pattern on the display D0 and having a sighting vector {right arrow over (xl)} determined as a function of the position Pi, and for each sighting Vi, acquiring the corresponding measurement of the relative angular orientation of the tracking element relative to a DDP reference direction, that is fixed relative to the platform of the aircraft, then
• computing the matrix of relative orientation M01 between the display D0 in the tilted position and the tracking first element D1 as the right matrix {circumflex over (D)}, the solution of the system of equations:
• Ĝ.{circumflex over (K)}i.{circumflex over (D)}.{right arrow over (x)}i={right arrow over (y)}0 for i=1 to N,
• the vector {right arrow over (y0)} denoting the vector in the inertial reference frame of the platform corresponding to the target point targeted in the outside real world and being unknown;
• and
• the left matrix Ĝ being the matrix M23 of relative orientation between the reference frame of the fixed second element D2, linked to the platform of the aircraft and the reference frame of the attitude inertial device D3, which is potentially incorrect but assumed constant as a function of time, and which, when it is unknown, requires at least four measurements {circumflex over (K)}l.