Underground Georeferencing via RFID Control Points
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Solution Overview
Problem
Current georeferencing methods for underground data face challenges such as drift error accumulation and the impracticality of using GPS and manual input, especially in long-term or deep underground environments, where existing systems are not effective in providing accurate alignment and error correction without reliable GPS signals.
Innovation Solution
A system utilizing a sparse set of surveyed control points, where control point profiling and nonrigid registration methods are employed, using technologies like RFID tags, laser scanners, and least-squares transformations to align and correct scanned data, allowing for open-loop and closed-loop mapping operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS is used for correcting drift error, then positioning accuracy is improved, but the system cannot operate underground where GPS signals are unavailable
Solution Approach 1:
The patent introduces RFID tags as intermediary reference objects that can be placed underground to serve as mediators between the mobile scanning system and the external coordinate system. These tags provide identifiable reference points that enable georeferencing without requiring GPS satellite signals, thus resolving the contradiction between maintaining positioning accuracy and adapting to underground environments.
Solution Approach 2:
The patent replaces the GPS-based electromagnetic positioning system with an RFID-based identification system. Instead of relying on satellite signals, the system uses RFID tags to provide reference information that can be read by the mobile scanner, substituting a mechanical/electromagnetic system that works underground for one that requires line-of-sight satellite communication.
2Measurement precision
If closed scan loops are used to correct drift error, then positioning accuracy is improved, but the method requires manual input and is impractical in real mines
Solution Approach 1:
The patent implements a self-service system where the mobile scanner automatically detects RFID tags and uses them to correct drift error without requiring manual intervention. The system autonomously identifies reference points, performs calculations to determine its position, and corrects accumulated errors, eliminating the need for operators to manually create closed scan loops or input control points.
Solution Approach 2:
The patent applies preliminary action by pre-placing RFID tags at known locations in the mine before scanning operations begin. These tags are positioned in advance to serve as reference points, allowing the mobile scanner to automatically identify them and use them for drift correction during normal scanning operations, rather than requiring post-processing of closed loops.
3Measurement precision
If stationary scanners with surveyed targets are used for georeferencing, then alignment accuracy is improved, but the system lacks mobility and requires installing physical targets
Solution Approach 1:
The patent creates a universal system where RFID tags serve multiple functions: they act as reference points for georeferencing, provide location identification, and enable drift correction. The same simple tag structure works with both stationary and mobile scanning systems, and can be used in various underground environments without requiring different target types or complex configuration procedures.
Solution Approach 2:
The patent extracts the essential function of physical survey targets from the georeferencing process. Instead of requiring large, visible, physically-installed targets that must be surveyed, the system uses small RFID tags that can be read remotely by the mobile scanner. This extracts the core function of providing reference points while eliminating the need for complex target installation and physical surveying procedures.
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
Enables accurate georeferencing and correction of drift errors in underground environments, facilitating efficient data alignment and reducing the need for dense surveyed data, thus improving the precision and practicality of underground mapping.
Implementation Method 1
RFID refers to a family of technologies providing radio frequency identification. RFID tags are small and cheap objects that can be read by radio frequency by RFID readers.
Implementation Method 2
laser scanning technology may be used
Data Source
AI summary
Known georeferencing techniques require input in the form of manually-chosen anchor points or dense surveyed data. The present invention is an improved method and system for georeferencing underground geometric data. The method comprises (a) visiting at least two control points; (b) obtaining information about each of the at least two control points using scanning means; (c) recording the information about the at least two control points into a computer processor; and (d) performing a best-fit transformation to the recorded information. Preferably, the scanning means comprises laser scanners and at least two radio-frequency identification (RFID) tags. However, other technologies, such as retro-reflective LIDAR targets, Wi-Fi access points or bar codes and a bar code reader may also be used. In addition, sonar, radar, flash LIDAR, MEMS LIDAR, or any other similar technology could be used.