Open Cut » Overburden Removal
ACARP project C20028 entitled "3D scan matching and registration for improved mine survey" endeavoured to reduce survey costs and improve the timeliness of survey data via the introduction of CSIRO's 3D mapping technologies to the survey process. It was intended to demonstrate the feasibility of these approaches via a low-cost mobile mapping platform and an associated short duration experimental program.
The project consisted of several development phases to determine the viability and assess the suitability of the proposed approach:
· Technology development;
· Site testing;
· Data review, analysis and reporting.
The site testing phase was conducted at BMA's Peak Downs mine over a 3 month period and a large amount of data was acquired for analysis. From this work, it was shown that the approach followed in this project, whilst showing promise, has failed to perform to an adequate standard in a real-world mining application.
In particular, the primary failures of the system can be categorised into two main subsets:
· Integral open-loop failures as exemplified by the drift in the spatial data results in areas with minimal change over the test period. An example of this is presented in Section 3.3.3;
· Gross alignment failures as exemplified by the errors that occur to the spatial data in regions of significant topological change. An example of this is presented in Section 3.3.4.
A number of options were presented to address these issues, the most promising was to upgrade to a low grade RTK GPS, improve the wheel odometry and improve the pitch estimation algorithm.
Care should be taken here to distinguish between the isolated areas of failure within this work and the capability of the underlying technologies. The research team believe that the technologies can be made to work in an open-cut mining environment, based in part on the significant success the groups has had with these technologies in a wide variety of other applications.
Two implementation paradigms were presented: one based around a small number of units per site, similar to this trial and a second where there is a larger number of units which provide frequent re-observations of areas in the mine that have undergone change.
For small deployments, the system's accuracy must be improved for the proposal to become a viable survey tool. The most readily available means to do this is to include increased sensor fidelity and accept the increased system cost. It is likely that this option would still prove cheaper than currently available commercial alternatives however the gap in pricing is unlikely to be sufficient to justify future development along these lines.
Contrasting to this, it is likely that a variation of the system would come into its own for large deployments giving high frequency updates. In this case the hardware upgrades may be more minimal and the component cost for the system likely to be only marginally higher than the proof of concept unit. Whilst the researchers and several industry members can see the potential for such a system and the ancillary applications and associated services that such a system could enable, as yet there is no viable business case for a large deployment providing frequent near-real time mine updates and such a system would require a leap of faith in further development investment.
It is likely that in the meantime, a system based around low cost unmanned aerial vehicle (UAV) mapping systems, such as Trimble's Gatewing platform, could likely provide similar functionality for a reduced investment at the mine site. There are significant accreditation hurdles for the legal operation of UAV's for commercial gain that pose a barrier to entry and adoption of such technologies.
At this stage the research team recommends that this work be put on hold until a more viable business argument can be proposed or more experience has been gained in the application of such technologies to large scale, low feature environments.
There is likely more merit in pursuing an investigation into the practicalities of using low-cost UAV's for survey tasks and the development and integration of those mapping technologies targeted towards infrastructure development, mobile plant maintenance and operator assistance.