Head Nod Recognition via Face and Gaze Angle Difference

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Solution Overview

Problem

Existing user intention recognition systems fail to accurately detect nodding and head shaking when users cannot gaze at a single point, such as while driving, as they require the user to focus on a specific direction, imposing limitations on the user's ability to interact effectively.

Innovation Solution

A recognizing apparatus comprising face direction sensing, line-of-sight direction sensing, and movement recognizing means that sets a reference direction based on the user's face and line-of-sight directions, allowing for accurate detection of nodding and head shaking by analyzing the difference between these directions, enabling recognition even when the user is not focused on a specific target.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the system requires the user to gaze at a specific point on the display section for intention recognition, then the recognition accuracy is improved, but the ease of operation deteriorates because the user cannot interact while performing other tasks like driving

Engineering Contradiction:
Improveintention recognition accuracyVSAvoiduser interaction convenience
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system changes the parameters used for intention recognition from requiring gaze direction at a specific display point to analyzing the angular relationship between face direction and line-of-sight direction. This parameter change allows intention recognition without requiring the user to focus on a specific point, thereby improving ease of operation while maintaining recognition accuracy

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system introduces an intermediary calculation method that uses the angular difference between face direction and line-of-sight direction as a mediator to determine user intention. Instead of directly requiring gaze at the display, the system calculates this angular relationship and uses it to infer intention, allowing users to interact naturally without breaking their focus on primary tasks

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the system uses only face direction sensing, then the device complexity is reduced, but the measurement precision of user intention deteriorates because it cannot distinguish between actual nodding and head movement due to device vibration or user posture changes

Engineering Contradiction:
Improvesensing system simplicityVSAvoidnodding detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The system merges face direction sensing and line-of-sight direction sensing into a unified intention recognition system. By combining these two sensing functions and analyzing their angular relationship, the system achieves high measurement precision in detecting nodding intentions while avoiding false positives from device vibration or posture changes that would affect only one sensor

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP1770596B1Apparatus, method, recording media, and program for recognition of head nodding.
Publication Date: 2010.01.27 OMRON CORP
  • EP1770596B1 patent drawingFigure 1
  • EP1770596B1 patent drawingFigure 2
  • EP1770596B1 patent drawingFigure 3

AI summary

The present invention enables a user's movement indicating his or her intention to be recognized easily and accurately. On the basis of image data taken by a camera 13, a face direction detecting section 11 senses the direction of a user's face and a line-of-sight sensing section 15 senses the direction of the user's line of sight. When the user's face is directed downward, while the user's line of sight is directed upward with respect to the face direction, a nod recognizing section 21 recognizes that the user has nodded. When the user's face is directed rightward or leftward, while the user's line of sight is directed in a direction laterally opposite to the face direction, a head shake recognizing section 22 recognizes that the user has shaken his or her head. The present invention is applicable to an intention checking apparatus that checks the driver's intention.