RFID Localization for Transport Robots in Branched Rail Networks
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Solution Overview
Problem
Existing methods for determining the location of transport robots in extensive rail networks face interference issues due to daylight and slow reaction speeds, especially at high speeds, and lack the complexity for independent navigation and logistical maneuvers.
Innovation Solution
The use of RFID tags at selected points in the rail network, combined with RFID readers on transport robots, enables precise location determination through near-field communication at 13.56 MHz, and the integration of permanent magnets for improved accuracy, utilizing a magnetic field for precise localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared data connection is used between stationary path marker and transport robot, then location can be communicated to the robot, but the connection is disturbed by daylight and has slow reaction speed making reliable transmission impossible at high speeds
Solution Approach 1:
The patent replaces the infrared optical connection with a radio frequency connection using RFID technology. The RFID reader on the transport robot communicates with RFID tags at location markers via electromagnetic fields at 13.56 MHz, eliminating susceptibility to daylight interference while maintaining location determination capability.
2Reliability
If infrared data connection is used between stationary path marker and transport robot, then location can be communicated to the robot, but the reaction speed is too slow for high-speed travel
Solution Approach 1:
The patent replaces the slow infrared data connection with RFID radio frequency communication. The near-field electromagnetic coupling between RFID reader and tag enables rapid data exchange that can keep up with high-speed robot travel, allowing location determination at speeds of at least 5 meters per second.
3Speed
If RFID tags and readers are used for location determination, then location can be determined quickly without interference, but the system requires reading and processing multiple tag identifiers
Solution Approach 1:
The patent extracts and utilizes only the essential identification function of RFID tags for location determination. By reading the unique identifier of the nearest RFID tag and mapping it to location coordinates, the system avoids the complexity of processing multiple simultaneous signals while maintaining high-speed location determination capability.
4Duration of action of stationary object
If passive RFID tags are used as location markers, then no power supply is needed giving almost unlimited service life, but the tags cannot actively transmit signals
Solution Approach 1:
The patent employs passive RFID tags that harvest energy from the electromagnetic field generated by the RFID reader. The tags contain no battery or power source, yet can be activated and transmit their identifier when the reader's electromagnetic field induces sufficient energy in the tag's antenna, enabling unlimited service life without active power consumption.
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 solution provides reliable, high-speed location determination with improved accuracy, reducing interference and enabling precise navigation, even at high speeds, with passive RFID tags offering long service life and enhanced positional accuracy to within 1 mm.
Implementation Method 1
This radio transmission via the RFID standard is not susceptible to interference because a near-field communication is sought, so that the corresponding signals are only transmitted over a distance of around 20 cm and no further signal propagation beyond this short range is necessary and desired. It works in the standard radio range of 13.56 megahertz
Implementation Method 2
a permanent magnet is arranged in the RFID tag itself or at a predetermined distance from the RFID tag and is connected to it. The permanent magnet builds up a permanent magnetic field in the direction of the passing transport robot, which has a suitable magnetic sensor next to this permanently arranged permanent magnet
Data Source
Figure 1~2
Figure 3~5
AI summary
Device for determining the location of transport robots (2, 3) in a rail network (1) with a radio connection (18) between the rail network (1) and a transport robot (2, 3) traveling on the rail network, wherein a number of RFID tags (8 to 13) are arranged at certain stationary location markers in the rail network (1) and each transport robot (2, 3) is assigned at least one RFID reader (14, 15) which is able to read the identifiers of the RFID tags (8 to 13) and process them as location information.