Head-worn Display Harmonization Using External Landmarks
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Solution Overview
Problem
Current head-worn display systems for aircraft require complex and error-prone calibration using a boresight reference unit, which adds bulk, weight, and installation complexity, and can lead to misalignment due to mechanical rigidity issues and vibratory environments.
Innovation Solution
A dual harmonization method for head-worn display systems that uses a transparent display, a head posture detection subsystem with a mobile tracking element securely attached to the display and a fixed element linked to the aircraft, along with an attitude inertial device, to compute the relative orientation and correct the display's alignment with the outside world through a series of sightings and iterative calculations, eliminating the need for a boresight reference unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a boresight reference unit is installed for harmonization, then alignment accuracy can be achieved, but device complexity and installation complexity increase
Solution Approach 1:
The patent extracts and eliminates the boresight reference unit from the system by using natural external landmarks (such as terrain features, buildings, or other fixed external objects) as reference points for harmonization. This removes the need for dedicated calibration equipment while maintaining alignment accuracy through iterative computation of orientation parameters based on sightings of external features.
Solution Approach 2:
The harmonization system is designed to work with any external landmark or feature in the environment, making the system universal and adaptable to different locations and conditions. The same system can use various types of external references (natural or artificial) for calibration, eliminating the need for specialized boresight equipment.
2Measurement precision
If a boresight reference unit is installed for harmonization, then alignment accuracy can be achieved, but weight and bulk increase
Solution Approach 1:
The boresight reference unit, which adds weight and bulk, is completely removed from the system. Instead, the patent uses lightweight computational methods that process sightings of external landmarks to calculate orientation parameters, eliminating the physical calibration equipment and its associated weight.
3Ease of operation
If mechanical rigidity is reduced for display mobility, then ease of operation improves, but reliability decreases due to misalignment risk
Solution Approach 1:
The system dynamically adapts to changes in display positioning by continuously or periodically performing harmonization calculations based on current sightings of external landmarks. This allows the display to be mobile and repositionable while maintaining accurate alignment through real-time computational correction of orientation parameters.
Solution Approach 2:
The system uses feedback from external landmark sightings to continuously correct and update orientation parameters. By comparing the observed position of external features with the expected position based on aircraft attitude, the system automatically compensates for any misalignment caused by display mobility or mechanical shifts.
4Measurement precision
If harmonization procedure is made frequent to account for misalignment, then alignment accuracy improves, but loss of time increases
Solution Approach 1:
The harmonization process is designed to be quickly performed by the operator using readily available external landmarks in the environment. The system enables self-service calibration where the operator simply sights external features and the system automatically computes the necessary corrections, eliminating the need for complex setup procedures or specialized equipment.
Data Source
AI summary
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 includes a step of acquisition of N measurements {circumflex over (K)}l of head postures by a series of different sightings Vi, each of which aligns a sighting pattern, situated at a different fixed position Pi on the display D0 with a sighting vector that is a function of the position Pi, then a step of computation of the matrix of relative orientation M01 between the display D0 in a tilted position of engagement in the field of view and the tracking first element D1 as the right matrix {circumflex over (D)} that is the solution of the dual harmonization system of equations Ĝ·{circumflex over (K)}i·{circumflex over (D)}·{right arrow over (x)}i={right arrow over (y)}0 for i varying from 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 fixed second element D2 and 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. A head-up display system is configured to implement the dual harmonization method.