Motion Sensor Peak Alternation Algorithm for Occupancy Detection
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Solution Overview
Problem
Conventional motion sensors using infrared radiation detectors face challenges in differentiating between human and animal movements, leading to high false alarm rates in intrusion detection while being insensitive to occupancy detection, which requires high sensitivity but can tolerate false alarms.
Innovation Solution
The development of a motion sensor employing a peak-alternation algorithm and slope synchrony method to differentiate between human and animal movements by analyzing the alternation of peaks in infrared detector signals from spatially-offset fields of view, ensuring low false intrusion detections and high sensitivity to occupancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motion sensors use infrared radiation detectors to detect motion, then they can detect movement in monitored space, but they cannot effectively differentiate between human and animal movements, leading to high false alarm rates
Solution Approach 1:
The patent divides the monitored space into multiple pyramidal volumes, each monitored by a separate detector element. This segmentation allows the system to analyze motion patterns in different spatial zones, enabling differentiation between human and animal movements based on which volumes are activated and their temporal sequences.
Solution Approach 2:
The patent adds a temporal dimension to the detection by analyzing the sequence and timing of peak alternations across multiple detector elements. By examining the time patterns of alternating signals from different pyramidal volumes, the system can distinguish human motion patterns from animal motion patterns, resolving the contradiction between detection sensitivity and false alarm reduction.
2Reliability
If motion sensors are optimized for intrusion detection with high rejection of false alarms, then they reduce false detections, but they become insensitive to occupancy detection which requires high sensitivity
Solution Approach 1:
The patent implements dynamic processing that adapts to different detection modes. The system can switch between intrusion detection mode (using peak alternation analysis for high reliability) and occupancy detection mode (using overall motion presence for high sensitivity). This dynamic adaptability allows the same hardware to optimize for different operational requirements without compromising either function.
3Reliability
If motion sensors use multiple detector elements to reduce false alarms, then they can cancel out ambient temperature changes and physical shock, but they increase device complexity
Solution Approach 1:
The patent uses an asymmetric arrangement where one detector element monitors a primary pyramidal volume while another monitors a secondary volume with different spatial characteristics. This asymmetric configuration, combined with the peak alternation algorithm, provides false alarm reduction through differential measurement while keeping the hardware configuration simpler than fully symmetric multi-element arrays.
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 solution effectively reduces false intrusion detections while maintaining high sensitivity for occupancy detection, ensuring accurate differentiation between human and animal movements, thereby improving the reliability of both intrusion and occupancy detection.
Implementation Method 1
An infrared detector detects changes in mid-infrared (IR) radiation having a wavelength of about 6-14 microns. These changes are due to temperature differences between a warm object, such as a warm blooded animal, and its background environment as the warm object moves through that environment.
Implementation Method 2
A typical IR detector utilizes a pyroelectric or piezoelectric substrate with a detector element that consists of conductive areas on opposite sides of the substrate, acting as a capacitor. As the substrate changes temperature, charge is added to or subtracted from the capacitor, changing the voltage across the capacitor.
Implementation Method 3
The optical array directs the IR radiation from multiple monitored volumes onto the infrared detector, and sometimes includes filters to minimize the radiation outside of the desired mid-infrared range from reaching the infrared detector.
Implementation Method 4
Each of the monitored volumes is typically a pyramidal shaped volume extending into the space to be monitored with the apex of the pyramid at the motion sensor. Concentrations of radiation from each of the pyramids are projected by the optical arrays on to the infrared detector where they are superimposed
Data Source
AI summary
A motion sensor has an infrared detector with a first set of detector elements coupled to a first channel and a second set of detector elements coupled to a second channel. A first optical subsystem directs infrared radiation from a first number of monitored volumes to the infrared detector and a second optical subsystem directs infrared radiation from a second number of monitored volumes to the infrared detector. Intrusion detection circuitry is coupled to both channels of the infrared detector and selects a set of peaks in the first channel and the second channel. It then calculates an alternation score based on a number of alternating peaks in the set of peaks, and indicates an intrusion detection based, at least in part, on the alternation score. The circuitry also determines a peak-to-peak period for the first channel and calculates a slope-synchrony measurement to modify the alternation score.