FMCW Radar Occupancy Detection with DC Offset Removal
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Solution Overview
Problem
Current radar-based occupant detection systems for vehicles are costly and inefficient due to the need for multiple sensors per seat, and conventional single-frequency Doppler radar systems fail to reliably indicate occupancy status or distinguish between interior and exterior objects.
Innovation Solution
A frequency modulated continuous wave (FMCW) radar system with DC offset removal and advanced signal processing, including object separation and vital sign monitoring, to generate occupancy status signals indicating the presence, classification, and vital signs of occupants within a vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional single frequency Doppler radar is used for motion sensing, then the system can detect motion, but it cannot reliably indicate occupancy status or distinguish between interior and exterior objects
Solution Approach 1:
The patent changes the frequency parameter of the radar system from a single frequency to multiple frequencies. By transmitting at multiple frequencies and analyzing the frequency-dependent reflections, the system can distinguish between interior and exterior objects more reliably, resolving the contradiction between motion detection capability and occupancy status reliability.
2Reliability
If each single seat is equipped with a separate radar sensor, then occupancy detection reliability is improved, but the system cost increases significantly
Solution Approach 1:
The patent merges multiple radar sensors into a single multi-frequency radar system. Instead of having separate sensors for each seat, one radar transmitter can illuminate multiple seats simultaneously at different frequencies, and the single receiver processes all reflections. This combining approach maintains occupancy detection reliability while significantly reducing system cost and complexity.
Solution Approach 2:
The single radar system is designed to perform multiple functions: detecting occupancy in multiple seats, classifying occupant presence, and distinguishing interior from exterior objects. By making the radar system universal and multi-functional, it replaces the need for dedicated sensors at each seat, reducing overall device complexity while maintaining reliability.
3Measurement precision
If foil based systems are integrated in every single seat, then occupancy classification accuracy is improved, but manufacturing costs increase
Solution Approach 1:
The patent replaces the mechanical foil-based contact sensing system with a contactless electromagnetic radar-based system. Instead of integrating physical foils into every seat, the radar system uses electromagnetic waves to detect occupancy and classification, eliminating the need for complex mechanical integration 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
The FMCW radar system effectively detects and classifies occupants, distinguishes between interior and exterior objects, and monitors vital signs with improved accuracy and reliability, reducing costs by eliminating the need for multiple sensors per seat.
Implementation Method 1
radar sensor system comprising an antenna system, at least one sensor and processing circuitry
Implementation Method 2
conventional single frequency Doppler radar as a motion sensor
Implementation Method 3
illuminating, using the antenna system, at least one occupiable position within the vehicle with continuous wave (CW signals), the CW signals being frequency modulated in time
Data Source
AI summary
A method for sensing occupancy status within an automotive vehicle uses a radar sensor system, the radar sensor system includes an antenna system, at least one sensor and processing circuitry. The method comprises illuminating, using the antenna system, at least one occupiable position within the vehicle with continuous wave (CW signals), the CW signals being frequency modulated in time. At least one sensor signal (y(t,f1 . . . y(t,fn)) reflected as a result of the CW signals, is received using at least one sensor the at least one sensor defining a plurality of receive channels (1 . . . i), each channel having a different frequency (f1 . . . fi). Processing circuitry is operable for applying, for each receive channel (1 . . . i), DC offset removal to the corresponding sensor signal (y(t,f1 . . . y(t,fn)) to generate a modified signal (y′(t, f1) . . . y′(t,fn)); and generating, based on the modified signals (y′(t, f1) . . . y′(t,fn)) one or more occupancy status signals, the occupancy status signal indicating a property related to said at least one occupiable position.