Multizone PIR Sensor Grid Tracking Heat Sources
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Solution Overview
Problem
Conventional passive infrared (PIR) detectors face limitations in tracking heat sources across multiple rooms and distinguishing between authorized and unauthorized movements, particularly in areas outside their field of view or when deceived by fixed heat sources like thermostatically controlled heaters.
Innovation Solution
A multizone PIR sensor system that generates a two-dimensional image of the monitored area, using a grid of cells to track heat sources and differentiate between authorized and secure zones, with a data processor analyzing heat signals to deliver alerts based on target position and movement history.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple PIR detectors are distributed in all rooms to track movements, then tracking precision and discrimination capability are improved, but device complexity and installation cost increase
Solution Approach 1:
The monitoring area is divided into multiple zones within a single room, with each zone having specific functions (entry, exit, secure areas, etc.). This segmentation allows the system to achieve detailed tracking precision without requiring detectors in every room, as the single detector can distinguish movements within different zones of the same room.
Solution Approach 2:
A single PIR detector is designed to perform multiple functions: detecting movements in all rooms, discriminating between authorized and unauthorized areas, tracking heat sources, and providing security monitoring. This multi-functionality reduces the overall system complexity while maintaining high tracking precision through intelligent analysis of heat source movements across different functional zones.
2Area of stationary object
If PIR detectors are placed in all rooms including corridors and vestibules, then coverage is improved, but device complexity and installation cost increase
Solution Approach 1:
The system transitions from a spatial distribution of detectors across multiple rooms to a functional zonation within a single room. By dividing the room into different functional zones (entry, exit, secure areas) and using a single detector to monitor all zones, the system achieves comprehensive coverage without increasing the number of detectors, thus reducing installation complexity.
3Ease of manufacture
If simple PIR detectors are used, then installation cost is reduced, but ability to discriminate between authorized and unauthorized movements deteriorates
Solution Approach 1:
Different zones within the room are assigned different quality characteristics based on their security importance. Secure areas have stricter monitoring requirements while entry/exit zones have different criteria. This local quality differentiation allows the system to achieve high discrimination capability by applying zone-specific detection rules, maintaining precision without requiring expensive complex detectors throughout.
Solution Approach 2:
The system changes the detection parameters dynamically based on the zone being monitored. Different zones have different thresholds and criteria for detecting authorized versus unauthorized movements. This parameter variation allows simple PIR detectors to achieve high discrimination capability by adapting their detection sensitivity and criteria to the specific security requirements of each zone.
4Area of stationary object
If PIR detectors monitor all areas including secure zones, then detection coverage is improved, but false alarms from fixed heat sources increase
Solution Approach 1:
The system performs preliminary classification of zones into secure and non-secure areas before detection begins. By pre-defining which zones are secure and what constitutes normal heat source behavior in each zone, the system can distinguish between authorized fixed heat sources (like radiators in non-secure zones) and actual intrusions in secure zones, thereby reducing false alarms while maintaining comprehensive detection coverage.
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 precise tracking and discrimination of heat sources within a room, reducing installation costs, eliminating the need for perimeter detectors, and providing autonomous operation with immunity to fixed heat sources, while allowing continuous monitoring without false alarms from legitimate occupants.
Implementation Method 1
a passive infrared sensor (PIR type), which delivers a sequence of thermal images of the zone to be monitored
Data Source
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AI summary
A multi-zone passive infrared sensor (10) produces a two-dimensional image consisting of a grid of cells corresponding to adjacent elementary zones (Zij) of a monitored zone (ZS), with each cell corresponding to a heat signal. The grid cells are classified as allowed and safe cells, and the equipment produces a target presence/absence indicator for each cell. When a target is detected in at least one cell, the processor conditionally issues an alert based on i) the position of the detected target on the grid and ii) whether the cell where the target is detected is classified as allowed or safe. A data memory (22) stores a history of the grid states, and the processor performs target tracking using an adjacent-cell algorithm based on this history.The alert takes into account the classification into authorized or secure squares of the squares successively occupied on the path of the target.