Thread-Based Strain Sensor for Head Motion Tracking
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Solution Overview
Problem
Current methods for monitoring human head motion, such as inertial-measurement devices and machine vision systems, are either invasive, imprecise, or cumbersome, failing to provide efficient and flexible real-time data on kinematic properties essential for understanding human behavior and attentiveness.
Innovation Solution
The use of thread-based sensors, or 'sensory threads,' which measure strain and are coated with conductive materials that change electrical properties with strain, allowing for real-time monitoring of head motion by intersecting threads arranged in configurations like 'X' or 'L' shapes, coupled with an electronic interface and data-processing system to classify head movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inertial-measurement devices (gyroscopes, accelerometers, magnetometers) are used to measure head motion, then measurement precision is improved, but device complexity and ease of operation deteriorate due to invasive placement requirements
Solution Approach 1:
The patent replaces mechanical inertial measurement devices (gyroscopes, accelerometers, magnetometers) with a textile-based sensor system that uses fiber optic strands embedded in fabric. This substitution eliminates the need for complex electronic inertial sensors while maintaining measurement capability through optical strain detection in the textile structure.
Solution Approach 2:
The patent employs flexible textile fabric as the sensor substrate, embedding fiber optic strands within the textile structure. This flexible textile approach replaces rigid electronic sensors, enabling comfortable wearability and non-invasive placement on the body while maintaining measurement functionality through strain-induced optical property changes in the fibers.
2Measurement precision
If inertial-measurement devices are placed on the forehead and vertebrae, then measurement precision is improved, but ease of operation deteriorates due to invasive placement
Solution Approach 1:
The patent uses flexible textile fabric as the sensor substrate, embedding fiber optic strands within the textile structure. This flexible textile approach replaces rigid electronic sensors, enabling comfortable wearability and non-invasive placement on the body while maintaining measurement functionality through strain-induced optical property changes in the fibers.
3Ease of operation
If stretch bands or virtual reality methods are used to measure neck range of motion, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent replaces mechanical stretch bands and virtual reality tracking methods with an optical sensing system using fiber optic strands embedded in textile. This substitution enables precise measurement of strain and motion through optical property changes (light transmission, refractive index) in the fibers, achieving high measurement precision while maintaining the ease of textile-based wearability.
4Ease of operation
If radar or machine vision systems are used for less precise measurements, then ease of operation is improved, but measurement precision and reliability deteriorate
Solution Approach 1:
The patent replaces external radar or machine vision systems with an integrated optical sensing system using fiber optic strands embedded in textile worn directly on the body. This substitution provides direct contactless measurement of head and neck motion through optical strain detection in the fibers, achieving high measurement precision while maintaining ease of operation through simple textile application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient, non-invasive, and precise monitoring of head kinematic properties, providing real-time data on head orientation and motion, suitable for applications in physical rehabilitation, augmented reality, and the study of human behavior without hindering daily activities.
Implementation Method 1
an extrinsically applied coating of conductive material undergoes a change in its electrical conductivity as a result of strain
Implementation Method 2
a first strand comprising a fiber optic strand having a core and a cladding that surrounds the core; the core and the cladding being formed from a single piece of material
Data Source
AI summary
An apparatus for sensing motion of a subject's head comprises three conductive threads, each of which has a resistance that varies in response to strain thereof, circuitry for applying a voltage across the threads, circuitry for detecting current flowing through the threads, a data-collection system configured to detect the current, and a data-processing system that classifies, based on data provided by the data-collection system, a type of motion of the head and an extent of the motion.