Radar Reflection Correlation for Vital Sign Clutter Discrimination
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Solution Overview
Problem
Existing technologies face challenges in accurately discriminating between reflections from a human body and stationary objects (clutter) due to periodic vibrations of the sensor, leading to inaccurate acquisition of biometric information such as vital signs.
Innovation Solution
An observation target detection device and method that calculates correlation degrees between temporal changes in amplitude, intensity, and phase of radar signals to identify reflection points, distinguishing between observation targets and non-observation targets based on predetermined thresholds, and removes displacement components caused by sensor vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sensor vibrates periodically due to disturbance, then the radar can detect reflections from the environment, but the periodic vibrations cause clutter reflections to be erroneously determined as human body reflections and superimpose periodic displacements on the measurements
Solution Approach 1:
The patent converts the harmful periodic vibration into a beneficial feature by using the correlation between amplitude and phase changes to identify and remove clutter reflections. The vibration that causes harm is transformed into a characteristic that helps distinguish clutter from actual human body reflections through correlation analysis.
Solution Approach 2:
The patent introduces correlation analysis as an intermediary mechanism between the raw radar signals and the final biometric information extraction. By calculating correlation between amplitude and phase temporal changes, the system mediates the interference from sensor vibrations and isolates the true human body reflection signals.
2Use of energy by moving object
If the sensor vibration is large compared to body surface displacement, then the vibration signal dominates the measurement, but discrimination between human body reflections and clutter becomes impossible
Solution Approach 1:
The patent changes the analysis parameters from direct signal amplitude comparison to correlation analysis between amplitude and phase temporal changes. This parameter transformation allows the system to distinguish between clutter and human body reflections even when the vibration signal dominates in terms of raw amplitude.
3Quantity of substance
If multiple reflection points are detected, then the radar captures all environmental reflections, but identifying which reflection point corresponds to the human body becomes difficult
Solution Approach 1:
The patent employs feedback through correlation analysis where the relationship between amplitude and phase temporal changes provides continuous feedback to identify the correct reflection point. This feedback mechanism allows the system to distinguish the human body reflection from multiple environmental reflections by detecting the unique correlation pattern of the vibrating sensor.
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
Enables accurate discrimination between human body reflections and clutter, improving the detection accuracy of vital signs like heart rate and respiratory rate by suppressing the influence of sensor vibrations.
Implementation Method 1
A system has been introduced to detect a human body by using a radar (RADAR: RAdio Detection And Ranging) and acquire biometric information based on a body surface displacement of the human body. In a radar system, reflected waves of radio waves emitted from an antenna are analyzed to identify a target.
Implementation Method 2
Patent Document 2 discloses an observation target detection device or an observation target detection method capable of detecting a target signal even if an antenna vibrates due to wind or the like, causing changes in ground clutter or apparent Doppler frequency of a target, by correcting the Doppler velocity based on a reflected wave component from the ground surface
Data Source
AI summary
An observation target detection device includes: a radar to identify a plurality of reflection points within an observation range based on reflected waves and circuitry to distinguish between an observation target and a non-observation target. The circuitry is configured to, for each of the plurality of reflection points, calculate a first correlation degree indicating correlation between temporal changes in a first signal property; select a set of candidate reflection points having the first correlation degree equal to or greater than a first predetermined value; calculate, when a number of reflection points selected is equal to or more than three, a second correlation degree indicating correlation between temporal changes in the first signal property for pairs of the reflection points; and determine that pairs having the second correlation degree equal to or greater than a second predetermined value are a non-observation target reflection points and otherwise are observation target reflection points.