Wearable Sensor Wear Detection via Multi-Sensor Fusion
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Solution Overview
Problem
Existing wearable sensor devices, such as watch-type sensors, face challenges in accurately detecting when they are being worn, leading to spurious data collection and power consumption issues due to inadequate wear detection methods.
Innovation Solution
A wearable sensor device combines heart rate and activity level information with optical sensing to determine if it is being worn, using a processor to analyze these metrics over a predetermined time period and deactivate sensors when not worn to conserve power and prevent erroneous data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If elementary wear detection is used (detecting if light path is blocked), then the implementation is simple, but the detection accuracy is insufficient and leads to erroneous results
Solution Approach 1:
The patent combines multiple detection methods (optical sensor for light path detection, motion sensor for movement detection, and ambient light sensor for environmental light detection) into a unified wear detection system. The processor integrates signals from all these sensors to determine wear status, resolving the contradiction by merging simple detection methods into a comprehensive system that maintains ease of implementation while achieving high detection accuracy.
2Reliability
If the sensor device continuously monitors to ensure accurate wear detection, then the detection reliability is improved, but the power consumption increases
Solution Approach 1:
The patent implements periodic monitoring where the processor evaluates sensor signals at specific intervals rather than continuously. The system monitors optical, motion, and ambient light signals periodically, determining wear status at discrete time points. This periodic action maintains detection reliability by regularly checking wear status while reducing power consumption compared to continuous monitoring.
3Measurement precision
If the sensor device uses multiple sensors and processing to accurately determine wear status, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent makes existing sensors serve multiple functions: the optical sensor detects both light path blockage (wear detection) and ambient light levels; the motion sensor detects both user movement (activity monitoring) and device movement (wear status); the ambient light sensor detects both environmental light (display control) and confirms device placement. This multi-functionality reduces the need for additional dedicated wear detection sensors, improving accuracy while limiting complexity increase.
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
This approach provides a reliable and power-efficient method for determining wear status, reducing spurious data collection and enhancing the accuracy of wear detection, thereby improving the operational efficiency of wearable health monitoring devices.
Implementation Method 1
an optical sensor for detecting incident light, and the light sensor is occluded when the device is worn
Implementation Method 2
a photoplethysmogram (PPG) sensor for heart rate sensing having an LED light source arrangement and a detector for detecting reflected light
Data Source
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Figure 4
AI summary
A wearable sensor device which comprises a heart rate monitor, a motion sensor and an optical sensor. The heart rate monitor output, the motion sensor output and the optical sensor output are processed to determine if the sensor device is currently being worn. In this way, a robust mechanism is provided for detecting when the sensor is being worn. Monitoring for the next transition from a not worn state back to a worn state is achieved with lowest possible power consumption by using only the optical sensing.