Dynamic Arctangent Center-Tracking Method for Respiratory Displacement Monitoring of Subjects in Arbitrary Positions

Area of Science:

• Biomedical Engineering
• Signal Processing
• Respiratory Monitoring

Background:

• Continuous wave Doppler radar offers a non-contact method for measuring respiratory displacement.
• Accurate measurements are challenged by DC offset variations due to subject movement.
• Existing methods require frequent recalibration or are sensitive to positional changes.

Purpose of the Study:

• To develop a robust dynamic calibration algorithm for Doppler radar-based respiratory displacement measurement.
• To enable continuous and accurate monitoring of respiration in both sedentary and non-sedentary conditions.
• To compensate for DC offset drift caused by subject positional changes.

Main Methods:

• Proposed a novel respiratory displacement measurement algorithm utilizing arctangent demodulation.
• Implemented a dynamic calibration technique to differentiate between sedentary and non-sedentary states.
• Validated the algorithm's performance in differentiating positional changes and adapting to subject movement.

Main Results:

• The proposed algorithm successfully differentiated between sedentary and non-sedentary conditions across six subjects.
• Demonstrated accurate sedentary respiration measurements despite arbitrary changes in subject position.
• Showcased the algorithm's ability to adapt and maintain measurement accuracy over time.

Conclusions:

• The developed dynamic calibration algorithm provides a robust solution for continuous respiratory monitoring using Doppler radar.
• This method enables long-term, accurate assessment of respiration without the need for frequent recalibration.
• The algorithm's adaptability to positional changes enhances its utility in real-world healthcare applications.