Head Worn Display Integrity Monitoring via Redundant Sensors
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Solution Overview
Problem
Current head worn display systems lack integrity monitoring for head tracking functions, which is crucial for maintaining accuracy and reliability, especially in aircraft applications, and there is a need for a low-cost solution that utilizes redundant sensors to detect symbology errors caused by head tracking sensors.
Innovation Solution
A monitoring system for head worn displays that includes a combiner and redundant head position sensors, where a computer compares symbology calculated from first sensor input values with those from second independent sensor values using an inverse algorithm to determine integrity errors and disable the display if errors exceed a tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant head position sensors are added to monitor integrity, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements integrity monitoring by creating a copy of the head position measurement system. A second independent head position sensor assembly provides redundant measurements that are processed through the same geometric relationships and comparison algorithms. This copying approach enables error detection without requiring a completely separate monitoring system, thus improving reliability while limiting the increase in device complexity.
Solution Approach 2:
The system continuously compares measurements from the first and second head position sensor assemblies and provides feedback about integrity status. The computer monitors the geometric relationships between sensor measurements and display symbology, and when discrepancies exceed thresholds, the system generates warnings or disables the display. This feedback mechanism enables real-time integrity monitoring that improves reliability without requiring permanent complex hardware modifications.
2Measurement precision
If head tracking errors are not monitored, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary monitoring actions by continuously checking the geometric relationships between head position sensor measurements and displayed symbology before errors can affect user perception. The system proactively compares measurements from redundant sensor assemblies and detects inconsistencies early in the measurement cycle, allowing for corrective action before precision is compromised.
Solution Approach 2:
The computer acts as an intermediary that processes measurements from both sensor assemblies, applies geometric transformation algorithms, and compares the results. This intermediary processing layer enables precision monitoring without requiring direct complex interactions between sensor components. The computer mediates the comparison of geometric relationships and triggers appropriate responses when precision thresholds are violated.
Data Source
AI summary
A head worn display system (e.g., helmet mounted (HMD) display system, and an eye wear mounted display system,) can include a combiner, a head position sensor and a computer. The computer provides symbology in response to first sensor input values associated with the head position. The symbology can be conformal with a real world scene. A monitoring system includes a redundant head position sensor for providing second sensor input values associated with head position. The computer monitors for positional accuracy of the symbology by comparing symbology calculated using the first and second input sensor values or by using an inverse function to compare sensor values.