Wearable Force Sensor Calibration via Orientation Detection
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Solution Overview
Problem
Force sensors in wearable devices degrade over time due to deformation, leading to reduced accuracy in bio-information estimation, particularly in measuring forces and pulse wave signals for blood pressure estimation.
Innovation Solution
A wearable device with a processor that guides users to position the device to measure specific forces, both with and without external objects, and calibrates the force sensor using these measurements, also utilizing a charging dock to adjust current levels for further calibration, ensuring accurate force measurement and blood pressure estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the force sensor is used continuously to measure bio-information, then the productivity of the wearable device is improved, but the measurement precision deteriorates due to sensor deformation over time
Solution Approach 1:
The system performs preliminary calibration actions at defined intervals (e.g., daily or weekly) to restore sensor accuracy before significant deformation occurs. The processor automatically schedules and executes calibration routines that measure known reference forces and adjust sensor readings accordingly, preventing cumulative precision loss during continuous operation.
Solution Approach 2:
The system implements feedback mechanisms where the processor continuously monitors sensor performance and compares it against reference values. When deviation exceeds a threshold, the system triggers recalibration. The processor uses feedback from calibration measurements to dynamically adjust sensor readings and maintain measurement precision throughout continuous use.
2Measurement precision
If the force sensor is calibrated frequently to maintain precision, then the measurement precision is improved, but the device complexity and calibration time increase
Solution Approach 1:
The force sensor system performs self-calibration using built-in reference weights or known force generators that are integrated into the wearable device. The processor automatically executes calibration routines without requiring external equipment or user intervention, reducing system complexity while maintaining precision. The device uses its own resources (processor, memory, integrated sensors) to perform calibration.
Solution Approach 2:
The system changes operational parameters such as calibration frequency, reference force values, and adjustment thresholds to optimize the balance between precision and complexity. The processor dynamically adjusts calibration intervals based on usage patterns and sensor degradation rates, performing more frequent calibration when precision is critical and reducing frequency when acceptable.
3Measurement precision
If calibration is performed with the main body facing upward and downward, then the measurement precision is improved through comprehensive calibration, but the ease of operation deteriorates due to additional positioning requirements
Solution Approach 1:
The system performs preliminary positioning guidance before calibration, using the display to show the user the correct orientation (main body facing upward or downward) and providing step-by-step instructions. The processor automatically detects when the device is in the correct position using internal sensors and only initiates calibration when positioning requirements are met, simplifying the user's task.
Solution Approach 2:
The system replaces manual positioning verification with automated detection using internal sensors such as accelerometers or gyroscopes. The processor uses these sensors to detect device orientation and confirm proper positioning before calibration, eliminating the need for complex mechanical positioning mechanisms or elaborate user procedures while maintaining calibration precision.
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
The solution enhances the accuracy and reliability of bio-information estimation by regularly calibrating the force sensor, maintaining precision despite deformation and environmental changes, and effectively estimating blood pressure through precise force and pulse wave signal analysis.
Implementation Method 1
a force sensor disposed on one surface of the main body and configured to measure a force... The force sensor that measures a force in this way may be subjected to deformation over time
Implementation Method 2
a pulse wave sensor disposed on the one surface of the main body and configured to measure a pulse wave signal
Data Source
AI summary
A wearable device includes a main body, a force sensor disposed on one surface of the main body and configured to measure a force, and a processor configured to control the force sensor to measure a first force when the one surface of the main body faces upwards, control the force sensor to measure a second force sensor when the one surface of the main body faces downward, and calibrate the force sensor based on at least one of the measured first force and the measured second force.