Active RFID Tag Positioning via Iterative Signal Intensity Vector
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Solution Overview
Problem
Existing RFID positioning systems using active RFID tags face inaccuracies in interior positioning due to unstable signal intensity changes, often resulting in misjudgments of distance and location, especially with barriers present.
Innovation Solution
A system and method utilizing multiple RFID readers to continuously adjust the positioned location of an active RFID tag by calculating signal intensities, determining an approaching vector based on the strongest signal, and iteratively updating the location coordinates until stability is reached, thereby improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-time positioning approach is used with triangulation, then the positioning system is simple, but the positioning precision deteriorates due to unstable signal intensity changes in interior environments
Solution Approach 1:
The patent implements continuous positioning by repeatedly performing signal intensity measurement and triangle area calculation at different time points. Instead of a single positioning operation, the system continuously updates the position of the moving object by executing the measurement-calculation-adjustment cycle multiple times, ensuring accurate tracking despite signal fluctuations.
Solution Approach 2:
The patent employs feedback mechanisms where the calculated position from triangle area comparison is used to adjust subsequent measurements. The system compares signal intensities at different locations, determines the moving object's position, and uses this information to guide further positioning adjustments, creating a closed-loop control system that compensates for signal instability.
2Device complexity
If direct signal intensity estimation is used to calculate possible distances, then the calculation process is simple, but the distance measurement precision deteriorates due to signal intensity changes caused by barriers
Solution Approach 1:
The patent performs multiple measurements and calculations beyond the minimum required for single-time positioning. By conducting repeated signal intensity measurements and triangle area calculations at different time points, the system gathers excess data that can be used to average out signal fluctuations and improve distance measurement accuracy despite the presence of barriers.
Solution Approach 2:
The patent changes the temporal parameter by performing measurements at different time points rather than relying on a single measurement. This time-based parameter change allows the system to capture signal intensity variations and use the evolution of triangle areas over time to accurately determine distance and position, compensating for barrier-induced signal changes.
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 approach enhances the precision of active RFID tag positioning by continuously refining the location based on signal intensity changes, reducing errors caused by unstable signal conditions and improving overall positioning accuracy.
Implementation Method 1
RFID (Radio Frequency Identification) system has two basic elements: RFID tag and RFID reader. When the RFID reader receives the RF signal from the active RFID tag, the RFID reader may estimate the distance between the active RFID tag and the RFID reader according to the changes of signal intensity (Radio Signal Strength Indicator, RSSI) of the RF signal.
Implementation Method 2
a passive RFID tag generates sensing current through magnetic induction to conduct the operation of the IC
Data Source
AI summary
A positioning system and method are provided to use multiple RFID readers to position a target object with an active RFID tag equipped thereon. The system and method defines a geometric center of the locations of the RFID readers as a first coordinate. When the RFID readers continuously receive RF signals of the active RFID tag, a corresponding signal intensity of each of the RF signals is calculated and compared to obtain an approaching vector corresponding to the location of the RFID reader with the greatest signal intensity of the RF signal. A positioned location of the target object is then approached from the first coordinate to a second coordinate according to the approaching vector. The first coordinate and the positioned location of the target object will be reset as the second coordinate. The reset first coordinate is output as the latest positioned location of the target object.