Methods and devices for activity monitoring in spaces utilizing an array of motion sensors
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Solution Overview
Problem
Existing occupancy sensing systems using passive infrared (PIR) motion sensors can incorrectly determine a space as unoccupied even when people are still present, leading to premature activation of building systems such as turning off lights or adjusting HVAC settings.
Innovation Solution
An array of motion sensors with a gate sensor and a processor that analyzes sensor data to determine occupancy characteristics by identifying the gate sensor, disregarding random motion, and calculating feature vectors to accurately determine when a space is empty, including the use of machine learning algorithms for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single PIR motion sensor with timer is used to detect occupancy, then the system is simple and cost-effective, but the occupancy determination is inaccurate leading to premature deactivation of building systems
Solution Approach 1:
The patent divides the monitoring task among multiple PIR motion sensors positioned at different locations within the space, each covering specific zones. This segmentation allows the system to track occupancy more accurately by monitoring multiple points simultaneously, resolving the contradiction between measurement precision and device complexity through distributed sensing rather than relying on a single sensor with complex logic.
Solution Approach 2:
The patent introduces spatial dimensionality by arranging sensors in a specific geometric configuration (e.g., corners of a room) and using their collective field of view coverage to determine occupancy. This multi-dimensional approach transforms the problem from temporal monitoring (single sensor over time) to spatial monitoring (multiple sensors simultaneously), improving accuracy without proportionally increasing complexity.
2Reliability
If a predetermined time duration is used after motion cessation to determine empty space, then the control logic is simple, but building systems deactivate prematurely when occupants are still present
Solution Approach 1:
The system continuously monitors the state of all motion sensors and uses this feedback to dynamically adjust occupancy determination. Rather than relying on a fixed timer, the system evaluates the collective state of multiple sensors in real-time, providing reliable occupancy detection without unnecessary time delays and enabling immediate response to actual occupancy changes.
3Measurement precision
If multiple motion sensors are deployed throughout the space, then occupancy detection accuracy is improved, but the device complexity and processing requirements increase
Solution Approach 1:
The patent combines the outputs of multiple PIR motion sensors into a unified occupancy determination logic. By merging sensor data and evaluating the collective state (e.g., if any sensor detects motion, the space is occupied), the system achieves high measurement precision while keeping processing complexity manageable through simple logical operations rather than complex algorithms.
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 prevents premature activation or deactivation of building systems by accurately determining occupancy and the number of people in a space, ensuring energy efficiency and comfort by maintaining appropriate conditions even when occupants are stationary or present.
Implementation Method 1
Passive infrared (PIR) motion sensors are often used for occupancy sensing
Data Source
AI summary
Aspects of the present disclosure include arrays of motion sensors that may be used to monitor a space to determine occupancy characteristics of the space, such as whether or not the space is occupied and the number of people located within the space. The array of motion sensors may be operatively connected to one or more building system components, such as lighting and HVAC equipment and can be used for adjusting an operating condition of the building system component based on whether a space is occupied.