EOG Calibration via Vestibulo-Ocular Reflex Correlation
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Solution Overview
Problem
Existing electrooculography (EOG) methods are limited in their ability to calibrate eye movement signals in real-world, free-living conditions, requiring controlled settings and being unsuitable for mobile or rugged environments, which restricts their use as a preventative health tool and for real-time monitoring.
Innovation Solution
A method and system that calibrate eye state data based on head state data during a vestibulo-ocular reflex (VOR), enabling continuous calibration and generating accurate eye angle measurements in free-living conditions by correlating eye movement data with head movement data using probabilistic models and Bayesian updating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EOG calibration is performed in controlled laboratory settings, then measurement precision is improved, but adaptability to free-living conditions deteriorates
Solution Approach 1:
The system performs automatic calibration using the subject's own VOR responses to head movements, eliminating the need for external calibration equipment or controlled settings. The calibration process is self-contained, using only the EOG sensors and inertial measurement unit already present in the wearable device.
Solution Approach 2:
The calibration approach transitions from static, controlled laboratory procedures to dynamic, real-world calibration during natural head movements. The system captures calibration data during actual VOR responses to head rotations, making the calibration process adaptable to free-living conditions rather than requiring fixed, controlled environments.
2Device complexity
If traditional EOG methods are used without VOR-based calibration, then device simplicity is maintained, but measurement precision deteriorates
Solution Approach 1:
The system combines EOG signals with inertial measurement unit data to capture both eye movement and head movement information. By merging these two data streams, the system enables VOR-based calibration without requiring separate, complex calibration equipment, thus improving precision while maintaining relative simplicity.
Solution Approach 2:
The calibration process transforms raw EOG voltage signals into accurate eye movement angles by applying calibration coefficients derived from VOR responses. This parameter transformation converts uncalibrated electrical signals into precise angular measurements of eye position and movement.
3Measurement precision
If calibration is performed only in controlled settings, then measurement precision is improved, but loss of time in free-living conditions deteriorates
Solution Approach 1:
The system performs calibration automatically in the background during natural head movements before actual eye tracking measurements are needed. This preliminary calibration occurs during normal activities without requiring separate calibration sessions, so when field deployment begins, the system is already calibrated and ready for immediate use.
Solution Approach 2:
The calibration process is continuous and occurs during natural, everyday head movements rather than requiring discrete, scheduled calibration sessions. The system continuously captures VOR responses during normal activities, maintaining calibration accuracy over time without interrupting the subject's routine or requiring dedicated calibration time.
Data Source
AI summary
A method for calibrating eye information includes receiving eye state data measured during a calibration period, receiving head state data measured during the calibration period, calibrating the eye state data based on the head state data, and generating an eye angle measurement based on the calibrated eye state data. Calibrating the eye state data may include correlating the eye state data with the head state data during a period when a vestibulo-ocular reflex occurs. In some implementations, the eye state data may include eye movement data and the head state data may include head movement data. The calibrated eye state data is considered to have improved accuracy and therefore may be used as a more reliable basis for determining a variety of health conditions.