Location tracking in underground mines can be traced back as far as the 1980s to when the main technology used was RFID (Radio Frequency Identification) Tag Readers placed in the roof of the tunnel. These would read RFID Tags placed on the miners and vehicles that move around. Technology advances have introduced new real-time location tracking systems (RTLS) such as WIFI, BLE, UWB, Scanning and – yes, even GNSS/GPS – for underground location tracking. But apart from GNSS tracking & Scanning, the most effective underground RTLS solutions all still work on the basis of having a “tag reader” read a “tag” and linking that unique information to a surveyed point underground.
Despite the main components of the technology existing for decades, the mines that take advantage of this technology are in the minority. So what makes underground location tracking so difficult?
- Ubiquity of tracking technology: There are a lot of RTLS solutions to choose from, each with their respective pros and cons. Until recently, integrating these technologies together to use the “best combination” was impossible. Mines had to choose one and live with it. With the advent of system integration, this isn’t the case anymore, making it possible to use multiple location tracking technologies seamlessly and effectively.
- The accuracy dilemma: What tracking accuracy underground is “good enough”? Zone-based tracking (using one of many “nearest node” type technologies) does add value in many instances. Maybe it is good enough to know where a miner is within 50-150m if we are trying to determine a location following a safety event. But, 50-150m accuracy simply isn’t enough if we want to track material types, automate production assignments, monitor drill hole orientation or understand productivity and improve safety procedures.
- Cost vs. benefit analysis: The real villain against effective underground tracking is cost. On surface, GPS tracking is so cost effective, it is actually common to find surface mining equipment with two, three or even more GPS receivers in-use at any given time. Underground, however, we don’t have the advantage of easily accessible satellites in the sky. Without a large investment in infrastructure, underground mines are stuck.
When choosing the right underground tracking technology, Ramjack recommends a system integration approach using the latest in interoperability to fight back against the standard challenges we’ve faced as an industry. This allows mines to capitalise on the best of numerous tracking technologies, such as: Time Difference of Arrival, Two-Way Ranging, Forward vs. Reverse tracking, Synthetic GPS, and signal strength triangulation, without suffering from the inherent shortfalls of any one piece of technology.
- Use integration to your advantage: Linking the various use cases for underground location tracking to the different technologies available immediately makes it seem like it is impossible to avoid a trade-off. However, with interoperability comes flexibility, and it is possible now to, for example, combine GNSS tracking for use in the decline (for seamless transition from surface) with signal strength triangulation in areas where it isn’t practical to maintain the synthetic GPS signal. Likewise, improving on very affordable BLE tracking with more advanced UWB – when sub-meter accuracy is required – is very easy with the right system integration partner.
- Focus accurate location tracking where you need it most: In those areas where zone-based tracking is sufficient, simple technology like WiFi Tracking is sufficient. It helps solve the cost-benefit challenge while satisfying the need for location information in real-time. Where accurate tracking is important – and more importantly, where continuous tracking is important – deploy Reverse BLE tracking and/or UWB technology to meet those requirements. Managing the trade-off between accuracy and cost isn’t as difficult as it once was and, knowing which technology to use in which use-case ensures useful information is being provided from your tracking system at all times.
- Separate your visualisation platform from your tracking technology: In the scenario where a mine wishes to stay agnostic to the specific technology it uses for location tracking, finding an over-arching platform that can support multiple tracking technology without impacting its visualisation capabilities is critical. Ensuring seamless transitions from GNSS tracking on surface and in the decline to accurate UWB tracking in the working areas improves usability and usefulness.
Unfortunately, when it comes to underground location tracking, we don’t have one technology standard like what we have on surface. At Ramjack, we advise focusing on the value of tracking applications recommending, for example, using location tracking at the face as the foundation for an effective Production Management system, featuring accelerated post-blast re-entry, real-time vehicle health monitoring and automated production recording. The goal, as we see it at Ramjack, is to deploy a stable, value-adding location tracking system flexible enough to scale as requirements (and applications) expand at the mine.