Active RFID Tag with Current-Sensing Cable Clamp
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Solution Overview
Problem
Wireless real-time location systems (RTLS) that track assets such as medical devices and manufacturing equipment fail to notify users whether the assets are actively being used, leading to inefficiencies and frustration.
Innovation Solution
An active RFID tag with a current-sensing cable clamp that monitors AC current consumption to determine the usage state of the asset, using magnetic sensors to estimate current flow and infer usage based on predefined thresholds, while also enabling battery recharging through magnetic field energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If wireless RTLS tracks asset location only, then system simplicity is maintained, but usage state information is lost
Solution Approach 1:
The patent combines location tracking and usage state monitoring into a single integrated RFID tag system. The tag simultaneously performs wireless communication for location tracking and current sensing for usage detection, merging two functions into one device to avoid information loss without proportionally increasing complexity.
Solution Approach 2:
The RFID tag is designed as a multi-functional device that serves both location tracking and usage state monitoring purposes. By making the tag universal, the system captures comprehensive asset information (location + usage state) without requiring separate dedicated devices, thus improving information completeness while controlling complexity.
2Duration of action of stationary object
If battery-powered RFID tags are used, then wireless operation is enabled, but frequent battery replacement is required
Solution Approach 1:
The system enables the RFID tag to recharge itself by harvesting energy from the AC power cable through which the asset receives power. The magnetic field generated by the AC current induces voltage in a coil within the cable clamp, automatically recharging the tag's battery without external intervention, thus extending operational duration and eliminating productivity interruptions.
Solution Approach 2:
Instead of discarding depleted batteries, the system recovers energy continuously from the AC power infrastructure already present in the environment. The magnetic field energy from the power cable is captured and stored, converting waste electromagnetic energy into useful charging power, thereby extending battery life and maintaining operational continuity.
3Measurement precision
If current sensing is added to RFID tag, then usage state monitoring is achieved, but device complexity increases
Solution Approach 1:
The cable clamp acts as an intermediary component that houses the magnetic sensors and current detection circuitry separately from the main RFID tag body. This modular approach allows precise current sensing while keeping the tag itself relatively simple, as the sensing functionality is distributed to a dedicated attachment component rather than integrated into the core tag architecture.
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 solution allows for accurate tracking of asset usage, reducing retrieval inefficiencies and eliminating the need for frequent battery replacements by harnessing power from the AC current, thereby lowering operational and material costs.
Implementation Method 1
The cable clamp includes a magnetic sensor, such as a Hall effect sensor, fluxgate magnetometer, or other magnetic sensor configured to detect a magnetic field generated by the AC current
Implementation Method 2
The processor may further determine that the AC current conveys power to recharge the battery
Data Source
AI summary
Configurations are provided for measuring electrical current flow through an AC power cable to a host device. An enclosure is provided that includes various components, such as components of an active RFID tag. A cable clamp is provided that is configured to attach the enclosure to the AC power cable. The cable clamp includes magnetic sensors that are responsive to electrical current flowing through the AC cable to generate signals indicative of the current flowing through the AC cable.