Active RF-based occupancy detection system with adaptive load control
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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 load control systems, which hampers energy efficiency measures and occupant safety.
Innovation Solution
An RF-based occupancy sensing system that detects the presence of mobile RF-emitting devices like cell phones to determine occupancy or vacancy, using RF detectors and load control devices to manage electrical loads without direct line of sight or object motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional occupancy sensors (PIR, ultrasonic) are used to detect motion and determine occupancy, then the system can control electrical loads automatically, but false triggering occurs due to lack of direct line of sight and object motion requirements
Solution Approach 1:
The patent replaces mechanical motion detection (PIR, ultrasonic sensors requiring object movement) with RF electromagnetic field detection. The RF detector continuously monitors for RF signals from mobile devices, eliminating the need for mechanical motion detection and direct line of sight requirements, thereby reducing false triggering while maintaining reliable occupancy detection.
2Measurement precision
If conventional occupancy sensors require direct line of sight for detection, then motion can be detected, but detection fails when view is blocked by partitions or objects
Solution Approach 1:
The patent substitutes optical/mechanical line-of-sight detection with RF electromagnetic signal detection. RF signals can penetrate walls and partitions that block visual and ultrasonic detection, allowing occupancy detection to function reliably even when physical partitions or objects obstruct the sensor's view of the space.
3Productivity
If conventional sensors detect only moving objects, then motion-based occupancy control is achieved, but stationary occupants remain undetected causing lights to turn off incorrectly
Solution Approach 1:
The patent replaces motion-based detection mechanisms with RF signal presence detection. The RF detector identifies occupancy by detecting the presence of RF-emitting mobile devices, regardless of whether the occupant is moving or stationary. This ensures continuous reliable detection of stationary occupants while maintaining energy efficiency through accurate vacancy detection when no RF signals are present.
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
Improves detection accuracy and reduces false triggering, enhancing energy efficiency and occupant safety by reliably controlling electrical loads based on the presence or absence of RF-emitting devices.
Implementation Method 1
an RF detector for detecting an occupancy or a vacancy in a space
Data Source
AI summary
A system for detecting occupancy in a target space includes a radio frequency (RF) signal generator, a wireless communication device detector, a memory unit, an occupancy signal generator, and a load control device. The RF signal generator emits signals that trigger responses from wearable communication devices within a predefined space. The wireless communication device detector detects these response signals. The memory unit stores identification information of the wearable communication devices, derived from the response signals. The occupancy signal generator determines occupancy status based on the detected response signals. The load control device controls power delivered to an electrical load in response to the occupancy signal generation.