US-based Kinetic Mesh wireless networks developer Rajant Corporation conducted digital mining tests in collaboration with multinational engineering company Sandvik to ensure that wireless communication can be used with the teleremote and autonomous vehicles destined for diamond major De Beers’ Venetia mine, in Limpopo.

The digital mining tests, undertaken in early 2022, involved underground testing with Sandvik AutoMine and included remote control and fully autonomous driving of Sandvik machines over the Rajant wireless network using loaders and drills streaming video. Exception handling and remote operation commands were also tested.

Effectively equipping teleremote and autonomous vehicles with wireless communications in deep-level mining environments boils down to physics, highlights Rajant global sales and marketing executive VP Geoff Smith.

He explains that all wireless solutions have strengths and weaknesses. Long-term evolution is designed for long-distance Internet access, receiving more data than it can transmit, while Wi-Fi is bi-directional but has a shorter range.

Further, the capacity of a network depends on the channel size. The higher the frequency, the greater the throughput, but the shorter the distance and the more significant the impact on data transmitted or received.

Meanwhile, gain (how well an antenna converts radio waves into electrical power and vice versa) equates to beamwidth on an antenna. Therefore, the higher the gain, the narrower the beam, which reduces coverage below the antenna but increases the distance over which it can receive or transmit data.

“Signals propagate underground very differently from above ground, so all antenna types are required. Autonomous vehicles require constant error-free communication, while teleremote requires very low latency and high uplink bandwidth for cameras, so the machine’s response to a remote user’s instruction is not delayed,” adds Smith.

Rajant has implemented multi-radio, peer-to-peer Kinetic Mesh and pairs multi-frequency broadband BreadCrumb nodes with special-purpose antennas.

“Multiradio is required when communicating peer-to-peer as one radio receives while the other radio transmits, so there is no loss of throughput or added latency. Peer-to-peer is required because [regardless of the technology used] there will always be coverage gaps,” states Smith.

InstaMesh, the ‘brain’ of Rajant’s BreadCrumbs, is constantly evaluating all possible paths for communication, so when a path becomes obstructed or temporarily unavailable, InstaMesh automatically uses a different radio or BreadCrumb to create a new path to route around the problem.

Communication Aids Safety, Efficiency

Sandvik Mining & Rock Solutions global automation product line and projects director Elen Toodu says Sandvik’s collaboration with Rajant enables safer and more efficient mining as it enables full use of the advanced systems offered by Sandvik’s mining machines.

“Testing and validating with Sandvik demonstrated the ability to maintain the network connections required, not only to ensure safe operations but to be able to stream live video from the machines as they operate autonomously,” says Sandvik Mining & Rock Solutions underground automation product line manager Jouni Koppanen.

Rajant BreadCrumbs are mounted at fixed points within the mine and on every vehicle to directly connect to the vehicle’s cameras and control safety systems. This ensures that the controlling systems have 100% connection to the onboard systems.

“In addition, our Kinetic Mesh network also allows for real-time personnel and asset monitoring,” advises Smith.

Rajant Kinetic Mesh networking is deployed at about 50 mines in sub-Saharan Africa, Smith tells Mining Weekly.

“We deployed the network at our first mine in 2005 and have deployments in the coldest and hottest parts of the world. Our equipment is designed to work reliably from –40 ºC to 70 ºC.”

The Kinetic Mesh architecture allows mines to easily introduce, relocate or remove network infrastructure without causing any network downtime.