Adaptive Electro-oculography Noise Reduction via Saccade Filtering

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Solution Overview

Problem

Existing electro-oculography noise reduction methods, such as those in Patent Literature 1, require frequent correction due to time-varying drift noise and do not effectively address high-frequency noise, making them impractical for improving the signal-to-noise ratio (S/N ratio) in electro-oculography measurements.

Innovation Solution

A noise reduction device that utilizes saccade information to adaptively determine filter properties, employing high pass or low pass filters to reduce noise in electro-oculography signals, with cutoff frequencies adjusted based on saccade time intervals, occurrence frequencies, or non-occurrence probabilities to enhance the S/N ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If drift noise reduction is performed by frequent correction using gaze-at-specified-position measurement, then drift noise reduction accuracy is improved, but measurement time and operational complexity increase

Engineering Contradiction:

Improvedrift noise reduction accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the filter cutoff frequency adaptive rather than fixed. The system dynamically adjusts the cutoff frequency based on the detected saccade time intervals, allowing the noise reduction system to respond to changing signal characteristics without requiring frequent manual recalibration or correction measurements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs self-service by automatically detecting saccade patterns from the electro-oculography signal itself and using this information to adjust filter parameters. This eliminates the need for separate correction measurements where the user must gaze at specified positions, as the system extracts useful information directly from the ongoing measurement signal.

Inventive Principle:

Principle #25Self-service

2Device complexity

If fixed filter cutoff frequency is used, then device complexity is reduced, but noise reduction effectiveness deteriorates due to time-varying noise characteristics

Engineering Contradiction:

Improvefilter control complexityVSAvoidnoise reduction effectiveness

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements feedback by detecting saccade time intervals from the electro-oculography signal and using this information to adjust the filter cutoff frequency. This closed-loop approach allows the system to adapt to time-varying noise characteristics while maintaining relatively simple device architecture, as the feedback is derived from the signal itself rather than requiring external control inputs.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system applies parameter changes by modifying the filter cutoff frequency based on detected saccade characteristics. Instead of using a fixed filter parameter, the system varies the cutoff frequency according to the temporal patterns of saccadic movements, thereby improving noise reduction effectiveness without significantly increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If saccade-based adaptive filtering is implemented, then noise reduction effectiveness is improved, but device complexity and processing requirements increase

Engineering Contradiction:

Improvenoise reduction effectivenessVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies taking out by extracting saccade time interval information from the electro-oculography signal and using only this specific feature for filter parameter adjustment. Rather than analyzing the entire signal spectrum or implementing complex adaptive algorithms, the system focuses on extracting the relevant temporal characteristic (saccade intervals) to control the filter, thereby achieving effective noise reduction with moderate processing requirements.

Inventive Principle:

Principle #2Taking out (Extraction)

4Measurement precision

If frequent correction measurements are required, then drift noise reduction accuracy is improved, but ease of operation deteriorates

Engineering Contradiction:

Improvedrift noise reduction accuracyVSAvoidoperational simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8430510B2Noise reduction device, electro-oculography measuring device, ophthalmological diagnosis device, eye-gaze tracking device, wearable camera, head-mounted display, electronic eyeglasses, noise reduction method, and recording medium

Publication Date: 2013.04.30 PANASONIC HOLDINGS CORP

AI summary

A noise reduction device includes: a saccade information obtaining unit that obtains saccade information from an electro-oculography original signal that indicates an electro-oculogram resulting from an eye movement of a user, the saccade information relating to a saccadic movement which is a rapid eyeball movement; a control unit that determines a filter property for reducing noise included in the electro-oculography original signal, on the basis of the saccade information obtained by the saccade information obtaining unit; and a filtering unit that reduces the noise included in the electro-oculography original signal using the filter property determined by the control unit, to output an electro-oculography signal.