Towards Automated Underground Mine Surveying: Integration of Mobile Mapping with Georeferenced Geometric Beacons
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Within the surveying community, more specifically in underground mining, the challenge for surveying and mapping is affordable, fast and accurate positioning that works well within constraints of underground mining environments. Current surveying methodology for underground environments has not changed much in the last half century. This thesis proposes use of new tools and procedures employed by the robotics community to provide opportunity to improve upon some methods of underground surveying and mapping. Underground mining environments comprised of ramps, shafts and tunnel type corridors link areas of mineral extraction to the surface environment. Since these environments are GPS-deprived, automatic positioning in a global context providing centimetre level positioning and single-digit, degree orientation is challenging, especially to mark the start and end of mobile mapping traverses. Current mobile mapping strategies use 2D and 3D laser scanners in conjunction with simultaneous localization and mapping (SLAM) techniques to map and model underground environments from point cloud data. These strategies currently operate mostly within local reference frameworks that can later be transformed to a global mine geodetic reference framework. They utilize beacon technology such as RFID tags, barcodes and other methods that include using natural features as beacons, providing positioning results outside the positioning accuracies required for surveying and mapping, in the mine surveying context. This thesis studies and makes contributions in several areas. First it compares and contrasts between conventional surveying and mapping, and mobile mapping. Second, it applies tools and techniques from mobile robotics to bear on problems and tasks in conventional surveying. It importantly focuses on fast, accurate and reliable registration of a mobile mapping tool to a global geodetic reference system, with minimal human input, whilst generating rigorously adjusted position estimates with associated uncertainties. Third, it demonstrates through experiments, strengths, weaknesses, advantages and disadvantages of the automated underground positioning method. Last, it highlights potential applications beyond surveying and mapping where this positioning method may be applicable. Within this list of contributions is the design, construction, calibration and testing of an equivalent mine reference system that uses geometric reference beacon technology to facilitate mobile positioning and mapping.