Dual Harmonization for Head-Up Display Posture Detection

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Solution Overview

Problem

Current posture detection systems in head-up display systems for aircraft and helicopters provide inaccurate raw output rotation matrices due to biases and misalignments, making it difficult to correct errors and requiring complex algorithms that are prone to errors from trigonometric functions, which are not effective for dual optimization of defects.

Innovation Solution

A method for dual harmonization of the posture detection subsystem that uses a series of relative orientation measurements and a dual harmonization algorithm to jointly calculate the relative orientation matrices, allowing for the determination of left and right-skew rotation matrices without knowing the sources of alteration, using a straightening operator to transform matrices into closest rotation matrices in a least squares sense.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex algorithms with trigonometric functions are used to correct posture detection errors, then measurement precision may be improved, but device complexity increases and errors from trigonometric functions are introduced

Engineering Contradiction:
Improveaccuracy of rotation matrixVSAvoidalgorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the harmful trigonometric functions from the correction algorithm, replacing them with a direct linear algebraic approach using rotation matrices. This removes the source of trigonometric errors while maintaining the ability to correct posture detection inaccuracies through matrix operations alone.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the mechanical/trigonometric computation system with a purely algebraic matrix system. Instead of using trigonometric functions to compute rotations, the invention uses rotation matrices and their properties (transpose, inverse, composition) to achieve the same rotational corrections without the computational complexity and error sources of trigonometric calculations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If partial harmonization methods are used to correct single biases, then ease of operation is maintained, but manufacturing precision deteriorates due to inability to correct multiple simultaneous defects

Engineering Contradiction:
Improvesimplicity of correction methodVSAvoidaccuracy of dual defect correction
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent merges the correction of left-bias and right-bias into a single unified algorithm. Instead of performing separate partial harmonizations for each bias type, the invention combines both corrections into one computational process that simultaneously determines and applies both rotation matrix corrections, enabling dual defect optimization in a single operation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a universal correction algorithm that can handle multiple types of biases (left-bias, right-bias, or both simultaneously) through a single harmonization process. This multi-functional approach allows the system to adapt to different error scenarios without requiring separate correction procedures for each bias type.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If multiple separate correction steps are performed for different biases, then reliability of individual corrections is maintained, but loss of time increases due to sequential processing

Engineering Contradiction:
Improveaccuracy of individual bias correctionVSAvoidcalibration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent combines multiple sequential correction steps into a single parallel processing operation. The unified harmonization algorithm simultaneously computes both left-bias and right-bias corrections in one execution, eliminating the need for sequential application of separate correction methods and thereby reducing total calibration time while maintaining correction accuracy.

Inventive Principle:
Principle #5Merging (Combining)

4Ease of manufacture

If corrective alignments are performed assuming single bias existence, then ease of manufacture is maintained, but measurement precision deteriorates when multiple biases are present

Engineering Contradiction:
Improvesimplicity of alignment procedureVSAvoidaccuracy of rotation output
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent implements a universal alignment procedure that does not require assumptions about the presence or type of bias. The harmonization algorithm is designed to automatically detect and correct any combination of left-bias and right-bias conditions, making the procedure robust to various error scenarios without requiring different alignment procedures for different bias configurations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3502843B1Dual harmonisation method for a head tracking system integrated into a worn head-up display system
Publication Date: 2022.10.19 THALES SA
  • EP3502843B1 patent drawingFigure 1
  • EP3502843B1 patent drawingFigure 2~3
  • EP3502843B1 patent drawingFigure 4

AI summary

A dual harmonization method of a DDP posture detection subsystem, integrated into a wearable head-up display system, comprises: .- a first step (54) of measuring N rotation matrices K̂ of posture detection of a head corresponding to a set of different sights Vi, in which one or more different predetermined elements of piloting information displayed in the display device Dv are superimposed or aligned with one or more corresponding landmarks of the outside real world; then .- a second step (56) of joint calculation of the relative orientation matrix R̂(S1/v) of the first tracking element S1 DDP towards the viewing device Dv and/or the relative orientation matrix R̂(ref/S2) of the external reference device DRef towards the second fixed solid element S2 DDP, respectively as the right-bias rotation matrix D̂ and the left-bias rotation matrix Ĝ solutions of the dual harmonization system of equations: Ûi = Ĝ · K̂i · D̂, i varying from 1 to N.