Underground » Roadway Development
The primary objective of this project was to investigate how laser scanning and processing technology could be used to determine the location of installed roof bolts in an underground coal mining roadway environment. Of secondary interest was the exploration of the degree to which roadway deformation (displacement) might also be measured using this laser profile data. No known commercial solutions or prototype demonstrators existed to address this complex monitoring and data processing scenario. The project commenced with a formal review of system requirements to understand the broad range of possible configurations, scanning platforms, sensor types, acquisition modes, generated data formats and quality and processing methods. This information was used to select the best combination of process, sensing hardware and software workflow to match the project objectives.
A series of in-house evaluations was first undertaken using CSIRO's scale roadway testing tunnel. The purpose was to establish ground truth measurements and to gain baseline performance expectations under ideal, controlled conditions. The specific technical challenges involved became clear through this process, requiring significant effort in development. Leading candidate algorithms were trialled and validated. For the bolt detection case, a high detection performance was achieved with a very low false positive rate. For the profile deformation case, however, it was clear that it would be extremely challenging to reliably detect roadway profile deformation of less than 10mm in an underground environment. Based on this finding, research subsequently focused on the bolt detection scenario with profile deformation evaluations concluding at an in-house testing stage.
Six underground evaluations were conducted at three different mine sites, collectively representing hundreds of metres of underground roadway. As anticipated, the underground represented a more complex environment due to the variability of the observed target configuration, platform motion, highly uneven surfaces, clutter and noise. However, bolt detection performance results of 80% - 85% were routinely achieved with a low false positive detection rate (<5%).
Overall the project objectives were successfully met with outcomes representing state of the art. One highlight was an evaluation of the ExScan unit on a continuous miner. It is believed by the researcher that this was the first time that live 3D laser scanning using had been undertaken under full production conditions and represented an important step towards future remote mining capability.