mmWave Radar Target Detection With Adaptive Thresholds in Rain and Snow
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Solution Overview
Problem
Existing sensors, such as motion sensors and infrared rain sensors, fail to accurately detect human targets during rainfall or snowfall conditions, leading to false activation of escalators and automatic doors, and are prone to wear and tear and performance fluctuations due to environmental factors.
Innovation Solution
A millimeter wave radar system with a radio frequency circuit and signal processing circuit that generates an adaptive filter threshold to differentiate between human targets and rainfall or snowfall, using pass-band Doppler filters and clutter maps to reject clutter and detect valid target signals, which can control the operation of appliances like escalators and automatic doors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion sensors are used to control escalators and automatic doors, then motion detection capability is provided, but false activation during rainfall or snowfall occurs
Solution Approach 1:
The radar system segments the detection process into multiple stages: initial target detection, rainfall/snowfall condition detection, adaptive threshold generation, and valid target signal generation. By dividing the detection process into distinct functional blocks, the system can separately optimize for motion detection while filtering out weather-related false positives through sequential processing stages.
Solution Approach 2:
The patent introduces an intermediary adaptive threshold mechanism that mediates between the raw radar signal and the final target detection decision. This threshold is dynamically adjusted based on detected rainfall or snowfall conditions, acting as a filter that allows genuine targets to pass through while blocking false positives generated by weather conditions.
2Measurement precision
If electrode rain sensors are used to detect rainfall, then presence detection is achieved, but wear and tear increases due to contact with rain drops
Solution Approach 1:
The patent replaces the mechanical contact-based electrode sensor system with a non-contact millimeter wave radar system. The radar detects rainfall and snowfall conditions through electromagnetic wave reflection and scattering from precipitation particles, eliminating the need for physical contact between the sensor and rain/snow drops, thereby eliminating wear and tear while maintaining detection capability.
3Loss of information
If IR sensors are used for rain detection, then basic rain presence information is provided, but additional information like quantity and speed cannot be obtained
Solution Approach 1:
The millimeter wave radar system performs multiple functions simultaneously: it detects the presence of rainfall and snowfall, measures their quantity through signal strength analysis, determines their speed through Doppler shift measurement, and uses this information to generate adaptive detection thresholds. This multi-functional approach replaces multiple specialized sensors with a single versatile radar system.
Solution Approach 2:
The radar system extracts multiple parameters from the reflected electromagnetic signals to characterize precipitation: signal amplitude provides information about precipitation quantity, Doppler frequency shift provides velocity information, and signal processing characteristics provide range and intensity data. By analyzing multiple parameters from a single sensor system, the patent obtains comprehensive precipitation information without requiring additional specialized sensors.
4Adaptability or versatility
If IR sensors are used for target detection, then operation is affected by lighting conditions, but the system can still function in various environments
Solution Approach 1:
The patent replaces optical-based IR sensors with millimeter wave radar that operates in the electromagnetic spectrum's microwave region. This substitution makes the detection system immune to visible light conditions, as radar waves are not affected by lighting, darkness, or optical interference. The system maintains consistent detection performance across all lighting conditions while providing reliable target detection.
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 system effectively detects human targets and measures rainfall/snowfall conditions, reducing false positive activations and improving energy efficiency by accurately controlling appliances in adverse weather, without being affected by lighting conditions and with minimal wear and tear.
Implementation Method 1
a radar system including a radio frequency (RF) circuit configured to generate a transmit signal and to receive a corresponding receive signal from a target during rainfall or snowfall conditions
Implementation Method 2
The signal processing circuit includes a plurality of pass-band Doppler filters
Data Source
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AI summary
A radar system includes a radio frequency (RF) circuit to generate a transmit signal and to receive a corresponding receive signal from a target during rainfall or snowfall conditions, and a signal processing circuit coupled to the RF circuit to generate an adaptive filter threshold in response to the rainfall or snowfall conditions, and to generate a valid target signal in response a portion of the receive signal above the adaptive filter threshold.