Doppler Radar Cross Section Estimation for Living Body Posture
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Solution Overview
Problem
Current methods for estimating the state of a living body, such as posture and action, using radio signals are limited in precision and speed, as they require prolonged observation and struggle to accurately detect direction and position due to small Doppler shifts from organic activities.
Innovation Solution
A sensor system with multiple transmission and reception antenna elements that calculate complex transfer functions to determine propagation characteristics, extract matrices affected by vital activities, and estimate the position and state of a living body using Doppler radar cross-section values, allowing for rapid and precise estimation of posture and action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler sensors are used to detect living body information, then the position and state of the living body can be detected, but the precision and speed of estimation are insufficient due to small Doppler shifts from organic activities
Solution Approach 1:
The patent segments the detection process into multiple stages: first detecting presence/absence, then estimating position, and finally determining state (posture/action). This segmentation allows each stage to be optimized independently, improving overall precision while managing detection complexity.
Solution Approach 2:
The patent introduces Doppler RCS (Radar Cross Section) as an additional dimension beyond traditional position detection. By calculating Doppler RCS values from position information and comparing them with threshold values, the system achieves more precise state estimation without relying solely on small Doppler shifts from organic activities.
2Measurement precision
If prolonged observation is used to estimate living body state, then estimation accuracy may improve, but the time required for detection increases
Solution Approach 1:
The patent performs preliminary presence determination before proceeding to position estimation and state detection. This preliminary action filters out cases where no living body is present, avoiding unnecessary prolonged observation time. Additionally, the system uses preliminary position estimation to calculate Doppler RCS values that can quickly indicate state information.
Solution Approach 2:
The patent implements a multi-stage detection flow that allows the system to skip certain processing steps based on intermediate results. For example, if presence is not detected, position estimation and state detection are skipped entirely. If position is detected but Doppler RCS indicates a clear state, detailed posture analysis can be rushed through or skipped, significantly reducing detection time while maintaining accuracy.
3Measurement precision
If multiple antenna elements are used to calculate complex transfer functions, then position and state estimation precision improves, but device complexity increases
Solution Approach 1:
The patent segments the complex signal processing into distinct functional blocks: matrix calculation for complex transfer functions, position estimation using extracted matrices, and Doppler RCS calculation. This segmentation allows each block to be optimized independently and implemented efficiently, managing device complexity while maintaining high precision.
Solution Approach 2:
The patent makes the position estimation unit and Doppler RCS calculation unit serve multiple functions. The position estimation unit not only estimates position but also provides information for Doppler RCS calculation. Similarly, the Doppler RCS calculation unit contributes to state determination. This multi-functionality reduces the need for separate dedicated components, managing device complexity while achieving high precision through multiple measurement dimensions.
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 rapid and highly precise estimation of a living body's state, including posture and action, by accurately determining position and vital activity-induced changes, overcoming the limitations of existing technologies.
Implementation Method 1
one or more reflected signals being one or more of the N transmission signals transmitted by the N transmission antenna elements that is reflected or scattered by the living body
Implementation Method 2
a Doppler radar cross section (RCS) calculation unit configured to (i) successively calculate a first distance and a second distance based on the position of the living, body successively estimated by the position estimation unit, a position of the transmission signal generator, and a position of the receiver, the first distance indicating a distance between the transmission signal generator and the position of the living body successively estimated, and the second distance indicating a distance between the living body and the receiver, and (ii) successively calculate a Doppler RCS value for the living body
Data Source
AI summary
A sensor includes: a transmission signal generator including N transmission antenna elements that respectively transmit N transmission signals to a predetermined range in which a living body is possibly present, where N is a natural number greater than or equal to 3; a receiver including M reception antenna elements that respectively receive N reception signals including one or more reflected signals, where M is a natural number greater than or equal to 3, the one or more reflected signals being one or more of the N transmission signals transmitted by the N transmission antenna elements that is reflected or scattered by the living body; circuitry; and memory. The circuitry estimates traveling of the living body, and/or the posture and/or action of the living body at the position of the living body.