Head-Referenced Attitude Director Indicator for Aircraft HUD
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Solution Overview
Problem
In head-mounted display systems for aircraft, the Attitude Director Indicator (ADI) symbols conventionally used for piloting information often move out of the pilot's visual field when the user turns their head, leading to loss of critical information and incoherence in representation, especially during aircraft attitude changes.
Innovation Solution
The ADI is represented in a reference linked to the head support, ensuring it remains within the pilot's field of vision, with adaptive symbology that includes a central airplane model, angular diameter adjustments, roll scale arcs, and pitch chevron symbols that appear only when specific angle or roll thresholds are exceeded, maintaining minimal visual footprint and clarity during critical flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ADI symbols are displayed in a conformal position superimposed on the external landscape, then the information is perfectly aligned with the aircraft's centerline and ground reference, but the symbols move out of the pilot's field of vision when the user turns their head
Solution Approach 1:
The patent applies the dynamics principle by making the ADI symbol display position adaptive rather than fixed. The system dynamically adjusts the symbol position between conformal (ground-referenced) and non-conformal (head-referenced) modes based on real-time detection of head orientation. When the head turns beyond a threshold angle, the display transitions from conformal alignment to a position that remains within the pilot's field of vision, thus maintaining both alignment precision and visibility continuously
Solution Approach 2:
The patent implements parameter changes by modifying the reference frame parameter for symbol display based on detected head orientation. The system changes the display coordinate system from a fixed ground-referenced frame to a head-referenced frame when the pilot turns their head, ensuring the symbols remain visible. This parameter switching resolves the contradiction by adapting the display behavior to the pilot's current viewing state
2Loss of information
If parking algorithms are used to bring ADI symbols to the edge of the field of vision, then the symbols remain visible during head movements, but the information consistency and symbol representation become lost or inappropriate
Solution Approach 1:
The patent resolves this contradiction by introducing a threshold parameter for head orientation that triggers a switch between two display modes. When head orientation exceeds the threshold, the system changes from conformal display to a head-referenced display mode, preserving information consistency. This conditional parameter change ensures symbols remain visible without distorting their meaning or representation
Solution Approach 2:
The system dynamically adapts the display mode based on real-time head orientation detection. Rather than using static parking algorithms that always position symbols at the field edge, the system transitions between conformal and non-conformal display modes dynamically, maintaining both visibility and information consistency appropriate to the current flight phase and head position
3Loss of information
If the ADI is displayed in a head-referenced coordinate system to ensure constant visibility, then the symbols remain in the pilot's field of vision during head movements, but the alignment with the aircraft's centerline and ground reference may be compromised
Solution Approach 1:
The patent applies dynamics by making the display reference frame adaptive. The system switches between ground-referenced (conformal) and head-referenced (non-conformal) coordinate systems based on detected head orientation. This dynamic switching ensures that when the pilot looks straight ahead, symbols are perfectly aligned with the ground reference, while when the pilot turns their head, symbols remain visible in the field of vision
Solution Approach 2:
The system changes the coordinate system parameter for symbol display based on the pilot's head orientation state. This parameter switching between conformal and non-conformal modes resolves the contradiction by ensuring the appropriate reference frame is used for each viewing condition, maintaining both alignment precision and visibility
Data Source
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AI summary
The general field of the invention is that of methods for displaying an "attitude director indicator" in a head visualization system for an aircraft comprising: - a head support (C) carrying a visualization device (V); - a posture detection (DDP); - sensors for detecting the different parameters defining the attitude of said aircraft; - means for calculating and graphically generating said attitude, the set of parameters displayed (S) being noted as "attitude director indicator";In the method according to the invention, when the head support is oriented in a determined direction making, with the horizon line and/or with the "velocity vector", an angle greater than a first value, and/or when at least one of the attitude parameters of the aircraft becomes greater than a second value, the attitude director indicator is displayed locally in a frame linked to the head support and in the field of the display device.