Occupancy sensing and lighting control using mobile device detection
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Solution Overview
Problem
Conventional occupancy sensors require a direct line of sight and object motion for detection, leading to false triggering and inefficient energy management, which hampers the adoption of energy-saving measures in buildings.
Innovation Solution
A radio frequency (RF) occupancy sensing load control system that detects the presence or absence of mobile RF-emitting devices such as cell phones to determine occupancy or vacancy conditions, allowing for independent detection without the need for direct line of sight or object motion, and integrates with existing sensors for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional occupancy sensors (PIR, ultrasonic) are used to detect motion for determining occupancy, then the system can detect moving objects, but it requires direct line of sight and object motion which causes false triggering and detection failures
Solution Approach 1:
The patent replaces mechanical/optical detection systems (PIR sensors, ultrasonic sensors) with electromagnetic field-based detection (RF sensors). This substitution eliminates the requirement for direct line of sight and object motion, as RF signals can penetrate walls and detect devices regardless of their position or movement state, thereby resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent introduces mobile devices (cell phones, PDAs) as intermediary objects that emit RF signals. These devices serve as proxies for human occupancy, allowing the system to detect presence without directly sensing the human body. This intermediary approach eliminates the need for direct line of sight and motion detection, improving both accuracy and reliability.
2Productivity
If conventional occupancy sensors are used, then the system can detect occupancy conditions, but false triggering occurs due to view-blocking objects, improper installation, or lack of motion
Solution Approach 1:
The patent replaces motion-based detection with RF signal-based detection, eliminating false triggers caused by view-blocking objects or improper sensor installation. RF signals can penetrate walls and detect devices regardless of sensor positioning or physical obstructions, ensuring reliable operation and improving energy management efficiency by accurately controlling loads based on true occupancy status.
3Measurement precision
If direct line of sight is required for sensor detection, then the sensor can detect objects, but the system fails when occupants are stationary or objects block the view
Solution Approach 1:
The patent replaces optical/mechanical line-of-sight detection with electromagnetic RF detection. RF signals can penetrate walls and detect mobile devices regardless of whether occupants are moving or stationary, and regardless of physical obstructions. This provides adaptability to all occupancy conditions while maintaining detection precision.
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 RF-based system effectively controls electrical loads by accurately detecting occupancy or vacancy, reducing false triggers and improving energy efficiency, while being compatible with various types of occupancy/vacancy sensing devices.
Implementation Method 1
a radio-frequency detector for detecting a presence or an absence of a mobile radio frequency emitting device within a predetermined distance from the sensor
Data Source
AI summary
A method for detecting occupancy and controlling electrical load based on the presence of mobile devices in a space is disclosed. An electric lighting fixture emits control signals into a surrounding area which triggers responses from nearby mobile phones that are not necessarily engaged in an active call. The lighting fixture receives response signals from mobile devices in the area and determines occupancy based on detection of the devices. The power delivery to the lighting fixture may be controlled based on occupancy. The method may further include providing audible or visual indicators of occupancy detection, requesting registration information from mobiles, storing mobile device IDs to ignore known devices, adjusting sensitivity of detection, controlling other electrical loads based on occupancy, and interfacing with a security system.