Adaptive Band-Pass Filter for Motion Artifact Compensation
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Solution Overview
Problem
Current non-contact video-based monitoring systems for physiological functions face challenges in compensating for motion-induced artifacts, which can lead to inaccurate heart rate measurements and discomfort for patients due to the need for continuous wear of contact sensors.
Innovation Solution
A method using an adaptive band-pass filter that re-configures based on previous video segment analysis to filter out motion-induced artifacts in sequential video segments, allowing for continuous and accurate heart rate monitoring without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact sensors are used for continuous physiological monitoring, then measurement precision is improved, but patient comfort and ease of operation deteriorate due to skin infection risks and psychological dependence
Solution Approach 1:
The patent replaces contact-based mechanical sensors with a non-contact video imaging system. The video camera captures physiological signals (such as heart rate) through optical means rather than physical contact, thereby maintaining measurement precision while eliminating skin infection risks and patient discomfort associated with continuous wear of contact sensors
2Ease of operation
If video imaging is used for non-contact physiological monitoring, then patient comfort is improved, but measurement precision deteriorates due to motion-induced artifacts
Solution Approach 1:
The patent implements a dynamic filtering approach where the band-pass filter parameters are continuously adjusted based on the detected pulse rate frequency. The system adapts the filter's center frequency and bandwidth in real-time to track the subject's physiological changes, thereby maintaining measurement precision even during motion. This dynamic adaptation allows the system to compensate for motion-induced artifacts while preserving patient comfort
Solution Approach 2:
The system changes the filter parameters (center frequency and bandwidth) dynamically based on the detected physiological signal characteristics. By adjusting these parameters in response to motion and physiological variations, the system maintains accurate heart rate measurement despite the non-contact nature of video imaging
3Device complexity
If a fixed band-pass filter is used to filter physiological signals, then device complexity is reduced, but adaptability deteriorates when pulse frequency changes occur
Solution Approach 1:
The patent implements a feedback mechanism where the detected pulse rate frequency from previous video segments is used to configure the band-pass filter parameters for the next segment. This closed-loop approach allows the system to automatically adapt to frequency changes while maintaining relatively simple device architecture, as the feedback is based on signal analysis rather than complex additional hardware
Data Source
AI summary
What is disclosed is a system and method for compensating for motion induced artifacts in physiological signals extracted from a video of a subject being monitored for a physiological function in a non-contact, remote sensing environment. The present method identifies a center frequency from a physiological signal obtained from processing a prior video segment. Since a moment to moment change in pulse frequency from one video segment to a next is not very large, signals obtained from sequential video segments can be repeatedly processed and an adaptive band-pass filter repeatedly re-configured and used to filter a next video segment, and so on. Using the teachings disclosed herein, a motion-compensated continuous cardiac signal can be obtained for the subject for continuous monitoring of the subject's cardiac function via video imaging. The teachings hereof provide an effective means for compensating for movement by the subject during video acquisition. Various embodiments are disclosed.