Head-Worn IMU Facial Expression Detection

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Solution Overview

Problem

Existing systems for detecting facial expressions face challenges in allowing high freedom of movement, adapting to changing ambient conditions, and ensuring unobtrusiveness, especially when portable.

Innovation Solution

An apparatus that receives information from at least one inertial measurement unit (IMU) worn on the user's head and determines facial expression information using machine learning algorithms, such as neural networks or hidden Markov models, to control electronic device functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional facial expression detection systems are used, then detection accuracy can be achieved, but head movement freedom is restricted and the system becomes obtrusive

Engineering Contradiction:

Improvefacial expression detection accuracyVSAvoidhead movement freedom

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces traditional mechanical/optical facial expression detection systems (cameras, mirrors, direct line-of-sight requirements) with an inertial measurement unit-based system that detects facial expressions through inertial signals from head movements. This substitution eliminates the need for fixed positioning and line-of-sight constraints, thereby improving head movement freedom while maintaining detection capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces inertial signals as an intermediary medium to detect facial expressions indirectly. Instead of directly observing facial features requiring line-of-sight, the system uses IMU sensors to capture inertial signals correlated with facial muscle movements, enabling detection without direct visual contact and thus improving ease of operation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If portable facial expression detection devices are used, then unobtrusiveness is improved, but detection reliability under changing ambient conditions deteriorates

Engineering Contradiction:

ImproveunobtrusivenessVSAvoiddetection reliability under changing conditions

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the detection parameter from visual/optical signals (which are sensitive to ambient lighting conditions) to inertial signals (which are independent of lighting conditions). By measuring acceleration, velocity, and position through IMU sensors, the system maintains reliable facial expression detection across varying ambient conditions while remaining portable and unobtrusive

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes optical detection mechanisms with inertial measurement mechanisms, replacing systems that rely on light reflection and camera imaging with sensors that detect physical movement and acceleration. This substitution eliminates sensitivity to ambient lighting conditions while maintaining portability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12299187B2Detection of facial expressions

Publication Date: 2025.05.13 NOKIA TECHNOLOGIES OY

AI summary

An apparatus comprising means for: receiving information from at least one inertial measurement unit configured to be worn on a user's head; and causing, at least in part, determining facial expression information in dependence on at least the received information.