One area that has eluded automation for years is the loading process of the underground LHD vehicles themselves. The challenge has always been how to create an automated system with the ability to effectively gauge the difference in size and configuration of rock piles as the loads are continually dispersed. Progress is also being stalled by underground conditions, which typically render camera technology ineffective by preventing the system from being able to ‘see’ the rock piles. In the coming years, automation will change underground mining beyond all recognition. Nnamdi Anyadike examines some of the key innovations currently underway, mining-technology.com noted.
Robotic tactile technology
A radical new technological breakthrough called auto-tunable robotic loading (ATRL), which is due to be rolled out later this year, may finally have cracked the problem.
The technology is the result of a unique collaboration between Queen’s Mining Systems Laboratory (MSL) in Canada; Örebro University‘s Centre for Applied Autonomous Sensor Systems in Sweden; and Atlas Copco Rock Drill, also of Sweden. The key difference is, ATRL allows automated LHD vehicles to ‘feel’ rather than ‘see’ the rock pile, and make their adjustments accordingly.
The ATRL system is based on a new development pioneered by MSL researchers, led by Joshua Marshall and Heshan Fernando, which uses admittance control. This views robotic loading from the perspective of modulating the admittance, i.e. the force / velocity relationship between the loader and rock pile. This tactile solution empowers the machine to work in dark and dusty environments without the need for camera technology.
Half-way to sorting automation
Marshall explains that, “The feeling is done by the existing sensors in the machine’s hydraulic cylinders. As the bucket moves in, forces push on it and the pressures change on the cylinders and we use those pressure signals to tell us about the level of bucket / rock interaction.” The aim is to ensure there is just enough bucket / rock interaction for the bucket to be filled. If there is too much force the bucket will get stuck: too little and it won’t be filled properly.
The challenge facing the team cannot be underestimated. LHD automation is complex and, typically, a remote-steered LHD vehicle can be equipped with up to 150 sensors. An MSL source said: “We are now half-way there and so far we have had some really great success. Our achievements are in no small part due to generous and unprecedented access to Atlas Copco’s Kvarntorp underground test mine and use of their fully equipped and automation-ready ST14 and ST18 LHD machines.”
When rolled out, the system will be available as a software upgrade for all Atlas Copco LHDs. It will include the capability to collect data on each dig for operators to compare the results of manual and autonomous digging.by