AR Glasses Pose Calibration Using Windshield Infrared Reflection

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Solution Overview

Problem

Current methods for determining the pose of augmented reality glasses in vehicles face challenges such as drift issues with inertial systems and the need for additional sensors in outside-in tracking, as well as the requirement for special markers in inside-out tracking, which can be aesthetically undesirable.

Innovation Solution

A system using a light source in the vehicle to illuminate the windshield with imperceptible light, combined with an optical detection device in the glasses to reflect and detect this light, allowing for pose determination without external interference, and utilizing a reflective layer to enhance light reflection and reduce external light impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If inertial measurement systems are used to determine the pose of augmented reality glasses, then the pose can be measured without additional external sensors, but the double integration of measurement results creates drift that quickly renders the tracking result unusable

Engineering Contradiction:
Improvesensor system complexityVSAvoidtracking precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines inertial measurement systems with optical measurement systems into a unified pose determination system. The inertial sensors (accelerometers and gyroscopes) in the augmented reality glasses provide continuous pose data, while the optical system (camera in the vehicle capturing markers on the glasses) provides periodic correction to eliminate drift. This merging allows the system to maintain high tracking precision without requiring complex external sensor arrays.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system implements feedback by using the optical measurement system to periodically correct the drift accumulated by the inertial measurement system. The camera captures images of markers on the glasses, calculates the actual pose, and uses this information to correct the inertial system's accumulated errors. This feedback mechanism ensures long-term tracking accuracy while maintaining system simplicity.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If outside-in tracking with additional sensor systems is used to determine the pose of augmented reality glasses, then tracking precision can be improved, but the system complexity and number of required sensors increase

Engineering Contradiction:
Improvetracking precisionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The augmented reality glasses perform self-service tracking by incorporating markers that can be detected by the vehicle's existing camera system. The glasses essentially provide their own tracking features (markers) that work with the vehicle's optical sensors, eliminating the need for complex dedicated tracking sensors in the vehicle. This self-service approach improves tracking precision while minimizing additional system complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent makes the vehicle's existing camera system multi-functional by using it both for driving assistance and for tracking the augmented reality glasses. The same camera that captures the driving environment also captures markers on the glasses, eliminating the need for separate dedicated tracking sensors and reducing overall system complexity while maintaining precision.

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

3Device complexity

If inside-out tracking with integrated measuring systems is used to determine the pose of augmented reality glasses, then the system complexity is reduced, but special markers must be installed in the vehicle which are aesthetically undesirable

Engineering Contradiction:
Improvesensor system complexityVSAvoidvehicle interior design
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

Instead of placing markers in the vehicle (inside-out tracking), the patent inverts the approach by placing markers on the augmented reality glasses themselves (outside-in tracking). The vehicle's camera system then detects these markers to determine pose. This inversion eliminates the need for aesthetically undesirable markers in the vehicle interior while maintaining simple system architecture.

Inventive Principle:
Principle #13The other way round (Inversion)

4Measurement precision

If optical measurement systems are used to determine the pose of augmented reality glasses, then tracking precision is improved, but the system requires additional sensors in the vehicle

Engineering Contradiction:
Improvetracking precisionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the vehicle's existing camera system multi-functional by using it both for driving assistance and for tracking the augmented reality glasses. The same camera that captures the driving environment also captures markers on the glasses, eliminating the need for separate dedicated tracking sensors and reducing overall system complexity while maintaining precision.

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

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method enables reliable and accurate pose determination of augmented reality glasses within a vehicle environment, reducing the need for additional sensors and markers, and allowing for autonomous calibration, thus improving tracking precision and user experience.

Implementation Method 1

at least one light source arranged in the motor vehicle for illuminating at least one windshield of the motor vehicle with light of a wavelength imperceptible to humans

Methodology Applied
Scientific EffectLight emission: Light

Implementation Method 2

the light striking the windshield, reflected by the windshield and striking an optical detection device arranged in augmented reality glasses

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3707547B1System and method for determining a pose of augmented reality glasses, system and method for calibrating augmented reality glasses, method for assisting a determination of the pose of augmented reality glasses and motor vehicle suitable for the method
Publication Date: 2024.07.31 VOLKSWAGEN AG
  • EP3707547B1 patent drawingFigure 1~2
  • EP3707547B1 patent drawingFigure 3~4
  • EP3707547B1 patent drawingFigure 5~6

AI summary

A system and a method for determining a pose of augmented reality glasses, a system and a method for calibrating augmented reality glasses, a method for assisting a determination of the pose of augmented reality glasses and a motor vehicle suitable for the method. For the purposes of assisting the determination of a pose, light at a wavelength not perceivable by humans is produced (10) by a light source. At least a windscreen of the motor vehicle is illuminated (11) by the light produced thus. The light reflected by the windscreen is detected (12) by an optical detection apparatus. A pose of the augmented reality glasses can be determined (13) on the basis of information detected by the optical detection apparatus. Likewise, a transformation rule for the augmented reality glasses can be ascertained (14) on the basis of the detected information.