Accelerometric Respiratory Monitoring via Thoracic and Abdominal Signal Reconstruction
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Solution Overview
Problem
Existing respiratory plethysmography bands are impractical due to their tendency to move and deteriorate during use, rendering their data unusable and making them difficult to use because of their fragility.
Innovation Solution
A method using a pair of networked three-dimensional accelerometers, one placed on the thorax and the other on the abdomen, to reconstruct the equivalent of an Inductance Respiratory Plethysmography (PRI) signal, effectively creating a virtual respiratory plethysmograph.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If respiratory plethysmography bands are used for respiratory monitoring, then respiratory function can be measured, but the device moves and deteriorates during use, rendering data unusable
Solution Approach 1:
The patent replaces the mechanical plethysmography band system with an accelerometric measurement system. Instead of using a physical band that wraps around the thorax and abdomen (which moves and deteriorates), the invention uses accelerometers to measure respiratory movements. This substitution of the measurement principle eliminates the mechanical constraints and stability issues inherent in band-based systems.
Solution Approach 2:
The patent creates a virtual respiratory plethysmograph by processing accelerometric signals to reconstruct the respiratory waveform that would be obtained from traditional plethysmography. The accelerometers capture thoracic and abdominal movements, and through signal processing (including gravitational reference and waveform reconstruction), a virtual PRI signal is generated that copies the functionality of traditional plethysmography without its mechanical drawbacks.
2Reliability
If respiratory plethysmography bands are used, then respiratory measurement is possible, but the device is fragile and difficult to use
Solution Approach 1:
The patent replaces the complex mechanical band system with compact accelerometric sensors. The accelerometers are small, solid-state devices without moving parts, making them inherently more robust and easier to apply. The measurement capability is maintained through signal processing that reconstructs respiratory waveforms from the accelerometric data.
Solution Approach 2:
The patent changes the measurement parameters from direct mechanical displacement (band movement) to acceleration measurements. By measuring acceleration and integrating the signal (with gravitational reference), the system derives position and velocity information, providing a different physical basis for respiratory measurement that is more robust and easier to implement.
3Measurement precision
If traditional respiratory plethysmography is used, then respiratory function can be characterized, but the system is complex and expensive
Solution Approach 1:
The patent replaces complex mechanical plethysmography systems with compact accelerometric sensors and digital signal processing. The accelerometers capture three-dimensional movement data, and through algorithms including gravitational reference, filtering, and waveform reconstruction, the system derives precise respiratory characteristics. This approach maintains measurement precision while dramatically reducing system complexity and cost.
Solution Approach 2:
The patent uses three-dimensional accelerometers that measure acceleration along three orthogonal axes. By analyzing movements in multiple dimensions and referencing gravitational direction, the system extracts respiratory information with high precision. The multi-dimensional measurement capability provides robust respiratory characterization while using simpler, more compact hardware than traditional plethysmography systems.
Data Source
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AI summary
The invention relates to a signal processing method comprising the following steps: - previously recording in a memory a first initial signal that originates from a first set of at least one three-dimensional accelerometer (110) positioned in a thoracic position of an individual. It is basically characterised in that it further comprises: - previously recording in a memory a second initial signal that originates from a second set of at least one three-dimensional accelerometer (120) in an abdominal position of the individual, which signal is synchronised with the first signal; - processing the data of the first initial signal in order to compute a first final vector, representing thoracic forces experienced by the first set of at least one three-dimensional accelerometer; - processing the data of the second initial signal in order to compute a second final vector, representing abdominal forces experienced by the second set of at least one three-dimensional accelerometer.