UWB Motion Detection via Doppler Spectrum Analysis
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Solution Overview
Problem
Ultra-wideband sensors in vehicles lack sufficient spatial resolution to detect small movements, such as chest movements during respiration or quick footsteps, due to the need for precise distance information which is not available.
Innovation Solution
The method involves generating a time-variant channel impulse response by transmitting impulse radio signals and analyzing the Doppler spectrum to detect movements by transforming channel impulse responses from the time domain to the frequency domain, allowing for the identification of Doppler shifts and local maxima associated with moving objects, even when the distance is unknown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ultra-wideband sensors are used for motion detection in vehicles, then the device complexity is reduced by using existing sensors, but the measurement precision is insufficient to detect small movements due to lack of precise distance information
Solution Approach 1:
The patent transforms the channel impulse response from the time domain to the frequency domain to extract Doppler shift information. This parameter transformation enables the detection of small movements by analyzing frequency changes rather than relying on precise distance measurements, thereby resolving the contradiction between using simple existing sensors and achieving high measurement precision
Solution Approach 2:
The patent introduces Doppler spectrum analysis as an intermediary processing step between the ultra-wideband sensor and the motion detection output. By analyzing the Doppler shift in the frequency domain, the system can detect small movements without requiring the sensor itself to have high spatial resolution, thus resolving the contradiction
2Measurement precision
If complex camera-based systems are used for motion detection, then the measurement precision is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent enables ultra-wideband sensors to perform multiple functions: both precise location determination of digital keys and motion detection of small movements. By making the sensor system universal, the patent eliminates the need for separate complex camera-based systems, thereby reducing device complexity while maintaining measurement precision through appropriate signal processing
Solution Approach 2:
The patent replaces complex optical-mechanical camera systems with electromagnetic wave-based ultra-wideband sensing. By substituting the mechanical/optical system with an electromagnetic system and using Doppler spectrum analysis, the patent achieves motion detection with simpler device architecture while maintaining or improving measurement precision
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 enables the detection of small movements by analyzing phase changes between successive channel impulse responses, allowing for the determination of movement and tracking, even if the change in location is below the spatial resolution of the sensor, and can differentiate between periodic and non-periodic movements.
Implementation Method 1
The method involves generating a time-variant channel impulse response by transmitting impulse radio signals and analyzing the Doppler spectrum to detect movements by transforming channel impulse responses from the time domain to the frequency domain, allowing for the identification of Doppler shifts and local maxima associated with moving objects
Implementation Method 2
This approach enables the detection of small movements by analyzing phase changes between successive channel impulse responses, allowing for the determination of movement and tracking, even if the change in location is below the spatial resolution of the sensor
Data Source
AI summary
An ultra-wideband sensor transmits impulse radio signals at different times and generates respective channel impulse responses that describe a respective reflected signal as a function of a path delay. The channel impulse responses are used to generate a time-variant channel impulse response in which the channel impulse responses are arranged according to the times of transmission of the respective associated impulse radio signals. At least one respective local maximum of the scatter function quantity, characterized by a respective Doppler frequency and a respective path delay, is detected in scatter functions of respective time windows. A predetermined selection method is used to select at least one local maximum as the respective observation maximum to be tracked for motion detection. A signal characteristic of the channel impulse response is generated for the respective observation maximum to be tracked and a predetermined motion detection method detects at least one predetermined movement.