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The Virtual Stope

With the price of platinum at $31,000 per kilogram, Sam has a bit of a challenge. Throw in a few ounces of rhodium at $10,000 per ounce, he’s actually got a massive challenge.

Sam is a shift supervisor working on an underground platinum mine in South Africa. And his job is to unearth maximum platinum ore from every blast, every day – with as little waste rock as possible. If he and his crews mess up, it is costly – each poor blast means a shallow advance, uneven faces, over- and underbreaks, even falling rock. All of which takes time to clean and make safe.

Maybe even worse – it could lead to a missed blast during the next shift cycle, at a production loss of nearly $20,000. With a target of 133 panels to be blasted every day, the pressure is on, and Sam is frequently missing targets.

Sam knows that production is key, but safety is king. If he could only get his crews to mark off their blasting patterns accurately, drill straight, and time the explosives in the correct sequence, the blast would hit the target – advancing deeper, straighter and safer. Every. Single. Day.

This, however, is easier said than done. Not that his team members are stupid, slow or lazy – Sam simply doesn’t have the means to train them effectively. Taking trainees nine hundred, or fifteen hundred or three thousand feet underground takes time. And it’s not only dark, dusty and damp, but also deafening and downright dangerous down there. This is not an environment where anybody wants to remain for long. People rush the job to get out, and there is no time to look at better practices to advance the blast accurately.

You simply can’t train people properly at such depths deep underground. How do you pass on decades of practical experience using PowerPoint slides? How do you get the trainees to grasp the true scale, distances and measurements of a stope panel? You can’t build muscle memory on a scaled-down, flat, 2D surface! And just how do you assess them to make sure they’re really competent? Sam’s even tried having them mark off the faces in 1:1 scale on the lawn outside – what a disaster!

Sam knows that as long as the crew remains inept, they’ll have poor blasts, making costly mistakes, missing the target.

Luckily though, there is light at the end of Sam’s tunnel – for Sam works for Anglo Platinum. And Anglo has embraced digitalization and i4.0. This visionary approach has set the stage for Sam’s custom-built solution. A masterly blended combination of 2,300ft³ training space, surrounded by an immersive 800ft² rear projection screen – held in place by about 2,000ft of aluminium tubing. With one monster PC driving 12 digital projectors and another monitoring 20 state-of-the-art Vicon tracking cameras. All of these brought to life by over 4,300ft of electrical and signal cabling.

Figure 1: The VR Stope Panel as seen from the Centre Gully. The correct blast marking and timing pattern is displayed.

To turn this flight of fantasy to a functional fact, Anglo approached a Pretoria-based company with over 15 years of experience in building safety training solutions for the mining industry. Boasting various Virtual Reality HMD (Head Mount Display) training programs, an immersive VR Cube, seven VR Blast Walls, and a VR Robotics Simulator, STS3D packed the experience to make this happen.

The VR Stope is massive – it has a production face panel of roughly 16.5ft-wide, 5ft-high and 13ft-deep; an Advanced Strike Gully, or ASG, which is 9ft-deep, 9ft-high, and 5ft-wide, and to the right is a siding of 5ft x 5ft x 7.5ft.

And the challenge was similarly massive – although designing and constructing the hardware, building the virtual stope, and coding the functions caused the STS3D team a few headaches, the really tricky part was how to track the users in real-time within this multi-dimensional stope. This required breaking new ground, so STS3D, being new to motion capture, turned to the best in the industry for expert assistance.

One company stood out – with the depth of their response, and their willingness to engage in an open conversation about how the system would work in the virtual mining environment, Vicon provided clarity and assurance.

Vicon quickly allayed the concern that cameras might not be able to track if markers were occluded by users. When Vicon convinced STS3D that their solution could track the subject accurately as long as a marker was visible to a single camera, the deal was clinched. The simplicity of plugging the Vicon sample data into the Unity game engine then added the cherry on the cake.

AngloAmerican trains 1,500 people per year and must be able to operate the system on-site without constant external support. Since a single instructor – without any prior experience in motion capture or Virtual Reality – only needs a one-button start to run the blast simulation, the Vicon system more than met the criterion of simplicity.

And since the Vicon system can track up to five people at once, this enables team learning and makes the training of big numbers of trainees possible – a must in the mining environment. This ability to track multiple objects through space provides very realistic training – preparing users for real conditions in the field.

During entry examination, for example, miners must decide whether a zone is safe for operations. If they get it wrong, they get a realistic simulation of what could happen. A big loud bang and sudden darkness simulate a potential rockfall on the spot where they are standing.

“Make no mistake – this gives the miners a real fright – they’ll remember their error. Since you are fully immersed in the virtual mine, there’s no room for distraction – and the learning sticks. You’re on high alert all the time while marking a pattern on the rock face for the drill operators. And when you detonate the blast, the rock flies – creating a very vivid, a very memorable experience.” Johan Bouwer, STS3D project lead.

The VR Stope is a life-sized serious game. It has two modes – a training, and an assessment mode. In training mode, users are instructed step by step how and where to mark off the panel using a special virtual paintbrush. This builds muscle memory and motor skills, which will be recalled once back in the actual environment. The system provides immediate visual feedback on correct or wrong actions. The added ability to undo and retry allows for effective, short cycle, feedback and learning.

Once the user has completed marking and timing, they experience VR’s ‘art of the impossible’. When the detonation is set off right in front of them, they see the firing sequence and fragmentation of the rock – a frightening sight to behold. It also enables them to inspect the quality of the blast first-hand – again and again, in real-time or in slow motion, forward or reverse. The miners can now really understand how and why the correct blasting procedure works best.

After a blast, the cameras track the hard hat position of the trainee, adjusting the perspective of the projections. This creates a 3D depth illusion – showing that the face wall has in fact advanced. Trainees can then study the results of their blast, and immediately see if they have had a good or bad advance – another completely novel experience.

In the assessment mode, trainees mark the blasting pattern and time the detonation sequence of explosives themselves. Once the marking pattern is submitted, the system takes a screenshot of the trainee’s attempt. The image gets saved to their PDF report along with information on a number of attempts, accuracy, the time taken and the number of times assistance was requested.

Trainees compete for Top Score Bragging Rights – a level of gamification that goes beyond tricks like badges and achievements and that assists in making learning stick.
In the next phase of instructional design and deployment, STS3D will cover Safe Entry Examination, testing for ventilation and noxious gasses, support installation and rock strata control – resulting in life-threatening learning experiences – but in an environment which is as safe as houses.