RF Occupancy Sensing 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 inefficiencies in energy management, as they struggle to accurately determine occupancy or vacancy conditions, especially in complex spaces or with improper installation.
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, allowing for independent occupancy or vacancy detection without the need for direct line of sight or object motion, using RF signals to control electrical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional occupancy sensors (PIR, ultrasonic) are used to detect motion for determining occupancy conditions, then the system can control electrical loads based on detected motion, but the sensors require direct line of sight and object motion for detection, leading to false triggering and unreliable occupancy determination
Solution Approach 1:
The patent replaces mechanical/optical motion detection systems (PIR sensors, ultrasonic sensors) with a radio frequency electromagnetic field-based detection system. The RF detector continuously monitors for RF signals from mobile devices, eliminating the need for line-of-sight requirements and physical motion detection, thereby improving reliability while simplifying installation constraints
Solution Approach 2:
The patent introduces RF signals from mobile devices as an intermediary indicator of occupancy. Instead of directly detecting human presence through motion or thermal changes, the system detects the presence of RF-emitting devices that occupants carry, providing a reliable proxy for occupancy status without requiring direct observation of the occupants themselves
2Measurement precision
If conventional occupancy sensors are used, then the system can detect occupancy conditions, but false triggering occurs due to lack of direct line of sight, object motion requirements, and interference from room partitions or improper installation
Solution Approach 1:
The patent replaces line-of-sight-dependent optical and acoustic detection systems with RF electromagnetic field detection. RF signals can penetrate walls and partitions, eliminating false negatives caused by obstructions and improving detection accuracy in complex spatial configurations without requiring precise sensor positioning
Solution Approach 2:
The system leverages the RF signals that occupants already generate and carry with them (from their mobile devices) rather than requiring occupants to interact with the detection system or the system to actively scan for occupants. This passive detection approach eliminates false triggering while maintaining high detection accuracy
3Reliability
If RF occupancy sensing is implemented, then detection accuracy and reliability are enhanced without requiring direct line of sight or object motion, but the system requires detection of mobile RF-emitting devices
Solution Approach 1:
The RF detection system serves multiple functions: it detects occupancy presence, determines vacancy conditions, and provides continuous monitoring without requiring different sensor types for different scenarios. The single RF detection mechanism handles various occupancy scenarios (moving occupants, stationary occupants, obscured views) that would traditionally require multiple specialized sensors
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
This system enhances detection accuracy and reliability, reducing false triggering and improving energy management by utilizing widespread RF signals from personal devices, enabling precise control of electrical loads based on occupancy or vacancy conditions.
Implementation Method 1
a radio-frequency detector adapted to detect a presence or an absence of a personal radio-emitting communication device
Data Source
AI summary
An occupancy sensing lighting control system is disclosed. The occupancy sensing lighting control system includes an electric lighting fixture, a wireless communication unit associated with the electric lighting fixture, an occupancy condition generating device and a load control device configured to control the current supplied to the electric lighting fixture. The wireless communication unit includes a signal-generating device and a signal detector. The signal-generating device generates periodic control signals detectable by a mobile cellular phone device located within the illuminated space and being in a standby or idle mode. The signal detector detects communication signals generated by the mobile cellular phone device. The occupancy condition generating device determines occupancy condition in response to a detection of communication signals from the mobile cellular phone device.