CPR Compression Depth Calculation Using Acceleration and Magnetic Sensors
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Solution Overview
Problem
Existing compression depth calculating devices inaccurately measure compression depth when there is a sudden change in displacement during CPR, due to error components from unintentional vibrations and linear modeling of the chest, which fails to account for individual variations in physique and non-linear spring characteristics.
Innovation Solution
A device that uses a combination of acceleration sensors and magnetic sensors to calculate compression depth by applying second-order integration of acceleration data and correlating it with coil-to-coil distance, employing an average correlation to reduce noise and accurately measure depth even with sudden changes, incorporating non-linear modeling to account for individual variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If second-order integration of acceleration is used to calculate compression depth, then the calculation can be performed using a single sensor, but the measurement precision deteriorates due to error components from vibrations
Solution Approach 1:
The patent combines two different sensing approaches: acceleration sensor-based second-order integration and magnetic sensor-based coil-to-coil distance measurement. By merging these methods and calculating the correlation between them, the system leverages the simplicity of the acceleration sensor while using the magnetic sensor to correct vibration-induced errors, achieving both device simplicity and measurement precision.
2Measurement precision
If average value of compression depths from multiple operations is used, then the influence of vibration errors is reduced, but the ability to detect sudden changes in compression depth deteriorates
Solution Approach 1:
The system calculates the correlation between acceleration-based compression depth and magnetic sensor-based coil-to-coil distance in real-time. This feedback mechanism allows the system to dynamically adjust for vibration errors without relying on historical averages, enabling accurate detection of sudden changes in compression depth while maintaining precision through continuous correlation-based error reduction.
3Device complexity
If linear physical model is used for chest compression, then the calculation is simple, but the measurement precision deteriorates when compression displacement varies due to non-linear chest characteristics
Solution Approach 1:
The patent transforms the approach from using a fixed linear physical model to dynamically calculating compression depth based on the correlation between acceleration data and magnetic sensor data. This parameter change allows the system to adapt to varying chest characteristics and non-linear compression behaviors without requiring complex non-linear modeling, maintaining calculation simplicity while improving 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 device accurately calculates compression depth during CPR, even with varying displacement, by reducing noise and accounting for non-linear chest spring characteristics, thereby providing precise feedback to rescuers on compression depth and frequency.
Implementation Method 1
a compression depth calculating device which calculates a compression depth during a compression operation based on information acquired from a first sensor
Implementation Method 2
information corresponding to a magnitude of the compression of the compression operation from a second sensor
Data Source
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AI summary
A compression depth calculating device (1000) including: an acceleration sensor (13); a magnetic sensor (19); a first calculation section (233A) which obtains a correlation; and a second calculation section (233B) which calculates a compression depth Dr of a compression operation performed after the correlation (R) has been calculated, based on a coil-to-coil distance AD acquired from the magnetic sensor (19) and the correlation (R), when the compression operation is performed after the correlation has been calculated.