Radar Occupancy Detection Using GLRT for Stationary Subjects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing occupancy detectors, such as passive infrared sensors and cameras, are prone to false alarms due to environmental factors and privacy concerns, while radar systems struggle to detect stationary or low-velocity subjects and require complex spectrum analysis for real-time detection.
Innovation Solution
An occupancy detector using a radar system with a generalized likelihood ratio test (GLRT) on time-domain signals from a radar background and detection signal to determine subject presence or absence, employing a frequency modulated continuous wave radar with self-injection-locked technique for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive infrared sensors or cameras are used for occupancy detection, then the presence or absence of a moving target can be determined, but false alarm rate increases due to environmental temperature sensitivity and user privacy issues
Solution Approach 1:
The patent replaces optical-based sensors (infrared sensors and cameras) with radar technology. Radar uses electromagnetic waves to detect occupancy by measuring phase and time difference between transmitted and reflected signals, making it immune to environmental temperature variations and privacy concerns while maintaining detection accuracy
Solution Approach 2:
The patent changes the detection parameter from optical/infrared signals to radar electromagnetic signals. This parameter change enables the system to detect occupancy through phase and time difference measurements, which are not affected by environmental temperature and provide better reliability
2Reliability
If radar is used for occupancy detection, then penetration capability and immunity to environmental temperature are achieved, but stationary subjects or low-velocity subjects cannot be detected
Solution Approach 1:
The patent performs preliminary spectrum analysis on the radar observation signals to extract frequency information before making occupancy determination. This preliminary processing enables the system to detect stationary and low-velocity subjects by identifying characteristic frequency patterns in the radar signals
Solution Approach 2:
The patent transitions from time-domain radar signals to frequency-domain analysis through spectrum transformation. This dimensional change enables detection of stationary and low-velocity subjects by analyzing frequency characteristics that are not visible in the time domain alone
3Difficulty of detecting and measuring
If spectrum analysis of radar observation signals is performed for occupancy detection, then stationary or low-velocity subjects can be detected, but real-time detection becomes difficult due to increased computation complexity
Solution Approach 1:
The patent applies partial spectrum analysis focusing on specific frequency ranges and characteristics relevant to occupancy detection, rather than performing complete spectrum analysis. This selective approach reduces computation complexity while maintaining the ability to detect stationary and low-velocity subjects
Solution Approach 2:
The patent extracts only the essential frequency information from the radar signals that is necessary for occupancy determination. By extracting only the relevant spectral characteristics rather than processing the entire signal spectrum, the system achieves real-time detection with reduced computation complexity
4Measurement precision
If radar collects more data length for occupancy detection, then detection accuracy improves, but real-time detection capability decreases
Solution Approach 1:
The patent changes the analysis parameter from time-domain signal processing to frequency-domain spectrum analysis. This parameter change enables the system to achieve high detection accuracy with shorter observation times by extracting frequency characteristics that converge quickly, eliminating the trade-off between data length and real-time capability
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 accurate and real-time occupancy detection within a short observation time, reducing computation complexity and overcoming limitations of existing technologies.
Implementation Method 1
radar, which is capable of penetration, not affected by the environment temperature and does not show images of user, is proposed to replace passive infrared sensor and camera for occupancy detection
Implementation Method 2
Radar can detect the phase and time difference between transmitting signals and reflected signals to determine the presence or absence of a moving subject in the environment
Data Source
AI summary
An occupancy detector includes a radar and an occupancy analyzer. The radar is provided to output a radar background signal and a radar detection signal which are time-domain signals. The radar background signal is detected by the radar from an area when a subject is not occupying the area, and the radar detection signal is detected by the radar from the area when the presence of the subject is unknown. The occupancy analyzer is electrically connected to the radar to receive the radar background signal and the radar detection signal, and it is provided to analysis whether a subject is occupying the area based on the radar background signal and the radar detection signal through generalized likelihood ratio test (GLRT).