Wearable Magnet and Sensor Biomechanical Motion Measurement
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Solution Overview
Problem
Wearable smart devices face challenges in accurately measuring body position and orientation due to interference from soft magnetic materials and limitations in inferring motion from single-location sensors or earth's magnetic field estimates.
Innovation Solution
A system comprising a wearable magnet and magnetic sensors that determine distance and orientation metrics between body segments, using a biomechanical model to estimate relative posture and detect excessive movements, with optional additional sensors for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If soft magnetic materials are used in wearable items, then the device can be made more compact and wearable, but the readings relative to the earth's magnetic field are interfered with
Solution Approach 1:
The patent extracts the magnetic sensing function from the wearable device itself and places it in a separate stationary reference frame. The wearable item contains only the magnet, while the magnetic sensor is located in a stationary reference frame, eliminating the interference from soft magnetic materials in the wearable device on magnetic field readings.
Solution Approach 2:
The patent introduces a stationary reference frame as an intermediary between the wearable magnet and the magnetic sensor. This intermediary structure allows the magnetic field to be measured without the interfering soft magnetic materials being in close proximity to the sensor, thus resolving the measurement accuracy issue while maintaining device wearability.
2Device complexity
If sensors are positioned at a single location, then the device complexity is reduced, but the position and orientation of body parts becomes difficult to infer
Solution Approach 1:
The patent segments the measurement system into multiple components: a magnet attached to one body part and a magnetic sensor attached to another body part. This segmentation allows independent measurement of relative position and orientation between body parts, improving inference accuracy without requiring complex multi-sensor configurations at single locations.
Solution Approach 2:
The patent transitions from a single-location sensor approach to a distributed sensor-magnet system that measures relative metrics between different body parts. This dimensional shift from point-based to relationship-based measurement enables accurate inference of body position and orientation using simpler individual sensor components.
3Device complexity
If estimated orientations relative to the earth's magnetic field are used, then the measurement system is simplified, but the position and orientation of body parts becomes difficult to infer
Solution Approach 1:
The patent implements a feedback mechanism where the magnetic sensor continuously measures the magnetic field from the wearable magnet, and the system processes this feedback to calculate real-time relative position and orientation metrics. This feedback loop enables accurate body orientation inference while maintaining system simplicity by using a single type of sensor.
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 accurate measurement of biomechanical motion, detects unwanted movements, and provides notifications, improving the reliability of wearable device data while minimizing interference from soft magnetic materials.
Implementation Method 1
A wearable device configured to be attached to a second body segment includes a magnetic sensor for detecting a magnetic field intensity of the wearable magnet
Data Source
AI summary
A method for measuring body movement with a wearable device. The method includes receiving, from a magnetic sensor of the wearable device, first signal data indicative of a magnetic field of a wearable magnet, wherein the wearable device is placed on a first body segment and the wearable magnet is placed on a second body segment; determining, by a computing device based on the first signal data, a distance metric indicative of a relative distance between the wearable magnet and the wearable device, and an orientation metric indicative of an orientation relative to the wearable magnet; and determining a biomechanical model based on the type of body segment for the first body segment and the second body segment, wherein the biomechanical model includes a relationship constraint between the distance metric and the orientation metric.