Head Tracking Fiducial Drift Correction
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Solution Overview
Problem
Headtracking systems in aircraft cockpits can drift or become misaligned, leading to misalignment of critical flight information displayed to pilots, which can have catastrophic consequences.
Innovation Solution
A high-assurance headtracking system that uses ground-truth fiducial markers, including reflective or light-emitting diode markers, attached to both the head-worn display and the aircraft cockpit, with a camera and control processors to continuously monitor and correct the alignment by identifying known positions and orientations of static fiducial markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional headtracking systems are used without ground-truth fiducials, then the system complexity is reduced, but the alignment accuracy and reliability deteriorate due to drift and misalignment
Solution Approach 1:
The patent introduces ground-truth fiducial markers as intermediary reference objects between the headtracking system and the environment. These fiducials serve as mediators that provide known reference points for calibration and drift correction, enabling the system to achieve high measurement precision without requiring complex sensor fusion or active stabilization mechanisms
Solution Approach 2:
The system performs preliminary calibration by capturing images of ground-truth fiducial markers at known positions and orientations before normal operation. This preliminary action establishes a reference frame that compensates for subsequent drift and misalignment, allowing the system to maintain accuracy without continuous complex corrections
2Reliability
If ground-truth fiducial markers are added to the system, then the reliability of headtracking is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs inexpensive fiducial markers that can be easily manufactured and attached to the HWD and cockpit. These markers are simple visual references (such as printed patterns or colored targets) rather than complex electronic components, making them cost-effective and easy to replace if needed, thereby improving reliability without significantly increasing manufacturing complexity
3Measurement precision
If continuous monitoring of device pose is implemented, then the detection precision of misalignment is improved, but the loss of time for processing increases
Solution Approach 1:
The system implements periodic monitoring of device pose by capturing images at regular intervals rather than continuous monitoring. This periodic action maintains high detection precision for misalignment while reducing processing time and computational load, as the system only needs to analyze fiducial marker positions at discrete time points rather than continuously
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
Ensures precise alignment of displayed information with the pilot's line of sight, preventing misalignment errors and maintaining accurate visual intelligence during flight operations.
Implementation Method 1
the device-frame fiducial markers and the platform-frame static fiducial markers include reflective markers or constellations thereof
Implementation Method 2
the device-frame fiducial markers and the platform-frame static fiducial markers include light-emitting diodes (LED) or constellations thereof
Data Source
AI summary
A high-assurance headtracking system for a head worn display (HWD) incorporating ground-truth fiducials is disclosed. In embodiments, the headtracking system includes a camera fixed to a mobile platform (e.g., an aircraft cockpit) and oriented toward a pilot wearing the HWD. Images captured by the camera detect fiducial markers attached to the HWD (and fixed in a device reference frame) and static fiducial markers fixed to the mobile platform, each static fiducial marker including a constellation of individual markers having a known position and orientation in the platform reference frame. The headtracking system include control processors for analyzing the images and identifying therein the device-frame and static fiducial markers. The headtracking system determines a device pose of the HWD relative to the platform reference frame and monitors the device pose for drift or error based on the known positions of the identified static fiducial markers.