PIR Presence Sensor Threshold Adaptation for Small Movements
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Solution Overview
Problem
Existing PIR sensors struggle to accurately detect the presence of a person in a detection area when the person is stationary or making small movements, leading to false switching off of lighting systems, and adjusting the detection threshold to avoid noise introduces uncertainty in detection accuracy.
Innovation Solution
An adaptive presence detection threshold is calculated based on the characteristics of the sensor signal, adjusting over time to account for both the person's motion and environmental noise, ensuring accurate detection even with small movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed high threshold is used for presence detection, then false switching off is avoided, but small movements of persons are not detected accurately
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed threshold to a dynamically adapting threshold. The presence detection threshold is continuously adjusted based on the signal characteristics and detected movements, allowing the system to adapt to different movement sizes and environmental conditions while maintaining reliable detection accuracy.
Solution Approach 2:
The patent changes the threshold parameter dynamically rather than using a fixed value. The threshold is modified based on signal analysis, movement detection, and environmental factors, enabling the system to optimize its sensitivity for different scenarios such as large movements (walking) versus small movements (sitting with keyboard movements).
2Adaptability or versatility
If a low threshold is used to detect small movements, then sensitivity to small movements is improved, but false switching on due to thermal noise increases
Solution Approach 1:
The patent implements feedback mechanisms where the system continuously monitors signal characteristics and adjusts the threshold based on feedback from the sensor data. This feedback loop allows the system to distinguish between genuine small movements and thermal noise by analyzing signal patterns over time, reducing false detections while maintaining sensitivity.
Solution Approach 2:
The system performs preliminary analysis of signal characteristics before final threshold adjustment. By pre-analyzing signal patterns and using initial threshold values, the system prepares appropriate threshold settings in advance, enabling it to respond appropriately to both large and small movements while filtering out false signals from thermal noise.
3Reliability
If the threshold is adjusted to account for environmental noise, then false detections are reduced, but detection responsiveness to actual movements decreases
Solution Approach 1:
The threshold adaptation is made dynamic and responsive to actual movement conditions. The system quickly adjusts the threshold in response to detected movements while maintaining awareness of environmental noise characteristics, ensuring both reliable false detection reduction and rapid response to actual person movements.
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 adaptive threshold ensures that lighting systems remain on when a person is present, avoiding false switching off, while maintaining detection accuracy by adapting to the actual motion patterns and environmental conditions.
Implementation Method 1
These sensors react on heat sources that are moving in the detection area of the sensor. When a heat source is moving in the detection area, this is interpreted as a person being present in the detection area of the sensor.
Data Source
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AI summary
The invention regards a sensor system and a method for determining presence in a detection area and outputting a control signal. A signal sensed by a PIR sensor unit is supplied to a computing unit. The sensor system starts to output an indication signal indicative of presence of a person when a difference between a measurement value of the supplied signal and a reference value exceeds an initial presence detection threshold value, wherein the indication signal is maintained for a switch-on period. In a second period of a time interval, a portion of the supplied signal received in a first period of the time interval is analyzed with respect to the initial presence detection threshold value and an adapted presence detection threshold value to be applied in a following time interval is calculated based on the result of the analysis. In a second period of a succeeding time interval, a portion of the supplied signal received in a first period of the succeeding time interval is analyzed with respect to the adapted presence detection threshold value. Calculating an adapted presence detection threshold value and analyzing a portion of the supplied signal received in a succeeding time interval with respect to the adapted presence detection threshold value is repeated until a stop condition is fulfilled. The switch-on period is reset at the end of the actual time interval if, in that time interval, the difference between a measurement value of the supplied signal and the reference value exceeds the applicable presence detection threshold value.