Wearable Respiratory Monitor Using Tri-Sensor Quaternion Filtering
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Solution Overview
Problem
Current devices for monitoring respiratory rate are not suitable for continuous, accurate evaluation, especially in dynamic conditions such as walking, limiting their effectiveness in both hospital and home environments.
Innovation Solution
A wearable device with three inertial sensors (abdomen, thorax, and a reference sensor) using accelerometers, magnetometers, and gyroscopes, connected to a microprocessor and transmitter, processes quaternion signals to filter out non-respiratory movements, enabling continuous monitoring of respiratory rate through a control center with adaptive filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single accelerometer or simple thorax/abdomen system is used, then the device simplicity is maintained, but measurement precision deteriorates in dynamic conditions
Solution Approach 1:
The system is divided into three separate inertial sensors positioned at different body locations (thorax, abdomen, and reference location). Each sensor independently measures local movements, and the control center processes these segmented measurements to isolate respiratory components from other movements, thereby improving measurement precision while maintaining manageable device complexity through modular architecture
Solution Approach 2:
A reference inertial sensor is introduced as an intermediary element positioned at a location not subject to respiratory movements. This reference sensor mediates the distinction between respiratory and non-respiratory movements by providing a baseline for comparing thoracic and abdominal sensor data, enabling accurate respiratory rate measurement during dynamic activities
2Measurement precision
If inertial sensors are used to detect respiratory movements, then measurement capability is improved, but the device cannot distinguish respiratory movements from other body movements in dynamic conditions
Solution Approach 1:
The reference inertial sensor acts as a mediator that captures non-respiratory body movements without capturing respiratory movements. By comparing the reference sensor data with thoracic and abdominal sensor data, the system can subtract or filter out the harmful interference from patient movements, isolating the pure respiratory signal
Solution Approach 2:
Different sensors are placed at locations with different movement characteristics: the thoracic and abdominal sensors capture both respiratory and non-respiratory movements, while the reference sensor captures only non-respiratory movements. This local quality differentiation enables the system to distinguish and separate respiratory components from interfering movements through comparative analysis
3Reliability
If three inertial sensors are deployed, then reliability of respiratory rate monitoring is improved, but device complexity increases
Solution Approach 1:
The monitoring function is segmented across three specialized inertial sensors, each capturing specific movement information from different body locations. This segmentation distributes the measurement burden and improves reliability through redundant information, while the modular sensor design keeps individual components simple and manageable
Solution Approach 2:
The inertial sensors serve multiple functions: they detect respiratory movements, capture non-respiratory body movements, and provide reference data for filtering. This multi-functionality justifies the use of three sensors by maximizing the utility of each component, thereby improving reliability without proportionally increasing overall system complexity
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 provides reliable, error-free continuous monitoring of respiratory rate in both static and dynamic conditions by isolating respiratory components from other movements, enhancing the accuracy and usability of respiratory rate monitoring.
Implementation Method 1
Each inertial sensor comprises: an accelerometer, a magnetometer, and a gyroscope
Implementation Method 2
Each inertial sensor comprises: an accelerometer, a magnetometer, and a gyroscope
Implementation Method 3
Each inertial sensor comprises: an accelerometer, a magnetometer, and a gyroscope
Data Source
AI summary
A wearable device for continuous monitoring of the respiratory rate of a patient, using a first inertial sensor positioned on the abdomen, a second inertial sensor positioned on the thorax, and a third inertial sensor being positioned on a part of the body not subject to respiratory movements, fixed with respect to the torso. Each inertial sensor includes a microprocessor connected to a transmitter configured for processing the signals and supplying a signal represented by a quaternion that describes the orientation of the inertial sensors with respect to the Earth's reference system. A receiver is configured for receiving the abdominal quaternion of the first inertial sensor, the thoracic quaternion of the second inertial sensor, and the reference quaternion of the third inertial sensor and sending them to a control center configured for calculating the respiratory rate from the signals represented by a filtered abdominal quaternion and a filtered thoracic quaternion.