Radar Sensor Vital Sign Detection via Signal Correlation
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Solution Overview
Problem
Existing radar sensor systems for vehicle interior vital sign monitoring face challenges in distinguishing between occupant-related signals and noise caused by vehicle movements, leading to false alarms and inaccuracies due to factors like uneven road profiles, engine vibrations, and wind gusts.
Innovation Solution
A method that decomposes received radar signals into range and Doppler information, filters out static components, and uses correlation coefficients to differentiate between vital signs and external disturbances, generating an output signal for accurate vital sign detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radar sensor systems are used for vital sign detection in vehicle interiors, then contact-free and unnoticeable monitoring is achieved, but false alarms and detection inaccuracies occur due to noise from vehicle movements
Solution Approach 1:
The patent segments the radar signal processing into multiple independent stages: receiving radar waves, determining range and velocity information, removing static scene signals, determining Doppler frequencies, calculating correlation coefficients, and generating output signals. This segmentation allows each stage to be optimized independently to handle the challenge of distinguishing vital signs from vehicle movement noise.
Solution Approach 2:
The patent introduces correlation coefficients as an intermediary metric to compare dynamic range signals with static scene signals. This intermediary allows the system to objectively quantify the similarity between signals and distinguish whether they originate from vital signs or vehicle movements, thereby resolving the reliability issue caused by noise.
2Measurement precision
If additional signal processing steps are implemented to distinguish vital signs from noise, then detection accuracy improves, but system complexity increases
Solution Approach 1:
The patent performs preliminary removal of static scene signals from the radar signals before further processing. By pre-processing the signals to eliminate static components, the system reduces the complexity of subsequent analysis steps while maintaining high detection precision, as the remaining dynamic signals are easier to analyze for vital sign detection.
Solution Approach 2:
The patent applies partial action by selectively processing only the dynamic portions of radar signals that contain potential vital sign information, rather than processing the entire signal spectrum. This approach achieves high measurement precision without requiring excessive computational resources, as the system focuses only on relevant signal components.
3Loss of information
If the system processes all radar signals in detail, then no vital sign information is lost, but processing time and computational load increase
Solution Approach 1:
The patent extracts and removes static scene signals from the radar signals in an early processing stage. This extraction eliminates unnecessary computational processing of static components that do not contain vital sign information, thereby reducing processing time and computational load while preserving all relevant dynamic information for vital sign detection.
Solution Approach 2:
By preliminarily identifying and separating dynamic range signals from static scene signals, the system prepares the data in advance for more efficient processing. This preliminary action reduces the computational burden of subsequent steps while ensuring no vital sign information is lost, as the separation is performed based on signal characteristics rather than arbitrary thresholds.
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
This approach provides robust and reliable vital sign monitoring by effectively distinguishing between internal and external movements, reducing false alarms and improving the accuracy of occupant detection in vehicle interiors.
Implementation Method 1
determining range and velocity (i.e. Doppler) information from radar waves reflected by a scene in an interior of a vehicle
Implementation Method 2
determining range and velocity (i.e. Doppler) information from radar waves reflected by a scene
Data Source
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AI summary
A method of operating a radar sensor system (100) that is configured to determine range and velocity information from radar waves reflected by a scene in an interior (116) of a vehicle (114) for vital sign detection comprises steps to decompose reflected and received signals into range and velocity information, to measure the movement over time in specified range gates and to evaluate the similarities between them. Based on the characteristics of similar behaving range bins, it can be decided whether any detected movement is related to an internal or external disturbance or by vital signs.