By Hua Guo
Research Director, Coal Mining Research Program, CSIRO
Improving longwall mining safety, and with it productivity, is a priority for Australia’s leading applied research agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO). CSIRO’s Coal Mining Research Program, based at the Queensland Centre for Advanced Technologies, is made up of some 70 specialists who work with industry to improve ground stability and mine gas and fire control, and to develop advanced technologies that enhance workplace safety and productivity.
The team is credited for the development of an automation technology known as LASC (Longwall Automation Steering Committee), which is used by the majority of longwall mining operations in Australia.1,2 Its implementation has arguably improved longwall mining safety and productivity more than any other innovation in the last decade.3 The technology automates the longwall mining process and has improved safety by moving people away from the hazards of the mine’s working face. At the same time, LASC has delivered productivity gains of up to 10% during peak operating periods. Over the long term, this translates to a productivity gain of 5%, saving mine operators millions of dollars each year.
Today CSIRO is close to even more innovative advancements in its automation technology, by adapting this technology to the continuous miner (CM) operations used to develop underground coal mine roadways. This adaptation will again protect lives and boost productivity in an area that is widely considered a bottleneck in the coal supply chain.
A DESCRIPTION OF LASC TECHNOLOGY
LASC is a suite of enabling technologies and systems that allows longwall mining equipment of any brand to be automated using inertial navigation system (INS) technology. The INS technology allows the 3D position of the major elements of the longwall mining system to be measured accurately for the autonomous operation of mining systems underground.
The LASC suite automates the hazardous manual tasks of face alignment and steering, as well as horizon control. Thanks to a WiFi-enabled shearer communication system, a world’s first in the LASC project, the whole process can be controlled remotely.
Four technologies were developed to achieve automation and make up the LASC suite:
- Shearer Position Measurement System (SPMS)—a combination of software and hardware that measures and communicates the 3D position of the shearer, and processes the raw data to a meaningful format.
- Automated Face Alignment—software that allows the user to monitor and adjust the position of the shearer by sending corrections to the roof support control system to maximize production by keeping the longwall face straight.
- INS-Based Automated Horizon Control—a combination of software that manages the transfer of horizon information to the original equipment manufacturer’s (OEM) shearer control system and provides an interface for users to control, monitor, and adjust the shearer’s cutting horizons.
- Automated Creep Control—a system comprised of sensors mounted adjacent to the main gate to measure the cross gate road creep distance of the main gate hardware, and supporting software that displays the information and computes corrections.
INS ENABLING TECHNOLOGIES CONSTITUTE THE KEY BREAKTHROUGH
The key to achieving automation was developing effective enabling technologies that would open up the use of high-accuracy INS underground. The idea in itself was not new, and during the 1990s CSIRO demonstrated that it was possible to guide highwall mining machines using inertial navigation. Realizing that the principle could also be applied to measuring and controlling the motion of a longwall shearer, CSIRO began developing strategies that would allow an INS to be effectively used underground.
An INS calculates the position of a moving object based only on its motion without the need for an external reference, but a small error in the measurement is always present. This error increases over time and makes the INS unusable, so, from time to time, INS information needs to be checked against other navigation methods.
Above ground, almost all navigation systems use GPS to provide position information to correct or minimize measurement errors. It’s a different story underground, where GPS is unavailable, and the rough, dusty, and hazardous conditions hamper the use of other assistive methods.
CSIRO achieved long-term INS stability by using very high-quality, accurate, low-drift inertial measurement systems and then by ensuring the SPMS included a calculation of the (almost) closed path of the shearer throughout each shear cycle. The horizontal closing distance is used in a patented approach in the automated face alignment system to back-correct the shearer path at the completion of each shear cycle.
The result was a world-first system that could provide 3D measurement of the longwall shearing machine with constant, centimeter-order position accuracy, which is now widely used in the industry.
OTHER FACTORS THAT INFLUENCED THE SUCCESS OF LASC
Finding a way to track the 3D path of the shearer by developing multiple and diverse sensing technologies to support INS underground was a key technology breakthrough.
Other factors that contributed to LASC’s success include:
- Its design as an open-source platform, with freely available interconnection specifications allowing seamless integration with any brand of mining equipment
- A unique commercialization model with OEMs, based on a nonexclusive technology license
- The provision of guaranteed technical assistance to OEMs during the initial roll-out, including detailed implementation guides and access to upgrades
- The nonexclusive technology license, critical to LASC’s success, was brokered largely because mine operators led the push for automation
The technology development could not have occurred without collaborative support. The coal mining industry, through the Australian Coal Association Research Program (ACARP), provided funding for CSIRO’s automation research and development program, and viewed the resulting technology as a must-have safety feature. Industry participants required a nonexclusive technology license so that they could access it through any OEM industry supplier. OEMs supported this unique arrangement in recognition of the existing market interest, and the savings they had made on research and development activities.
ASSESSING THE EFFECTIVENESS
The fact that two thirds of Australian longwall mines are using LASC technology is a testament to the safety and productivity benefits it delivers. Exact figures are hard to obtain due to the commercially sensitive nature of the information; however, an independent evaluation conducted in 2014 by ACIL Allen Consulting found that LASC:
- contributes to improving the working conditions and safety of coal mine employees as it moves them away from the hazards of the longwall;
- will likely save mining firms millions of dollars annually as a result of improved safety;
- delivers productivity increases of up to 10% during peak periods, and, significantly, up to 5% over the long term.
LASC is able to directly improve productivity by up to 10% during peak periods because it facilitates consistency in the longwall mining machine. Over the long term, a 5% increase in productivity can be gained because LASC technology requires all other systems and machines in the mining operation to be in peak condition for automation to be achieved consistently.
When combined with the lower risk of accident and injury, this means fewer process delays and greater efficiency in the entire mining operation.
THE FUTURE OF LASC TECHNOLOGY
In just seven years since its commercialization, LASC technology has been adopted by the majority of OEMs—Joy Global, Caterpillar, Eickhoff, Kopex, and Nepean Longwall—for use in their mining machines.
With the strong uptake in the Australian market, CSIRO is now focused on international opportunities. One OEM has taken the technology to global markets and CSIRO is currently working with a number of others active in the Chinese and European markets.
CSIRO’s research team continues to make refinements to the performance of the overall system, particularly in the development of improved mining horizon-sensing strategies using techniques like thermal imaging for coal seam tracking.4,5 Improved horizon control will lead to further economic and new environmental benefits for mine operators through a reduction in the amount of ash. This ultimately results in a cleaner coal product.
Perhaps the most exciting recent developments are based on CSIRO’s ongoing investigations into enhanced inertial system mining applications. In research which is now near commercialization, extra performance has been extracted from inertial systems so that the back-correction step referred to earlier for shearer position measurement is not required, paving the way for “real-time LASC”, which will deliver even more productivity improvement for longwalls.6
CSIRO is also refining inertial navigation aiding strategies so that the technology can be used to automate navigation and control of the continuous miner operations used to develop longwall roadways.
PROMISING RESULTS FOR CONTINUOUS MINER APPLICATIONS
Roadway development has not experienced the same rate of innovation as other areas of longwall coal-mine production and, as a consequence, it continues to be a bottleneck in the coal supply chain. The application of automation technology in this context will speed up roadway development, with huge gains for productivity and personnel safety.
CSIRO is nearing the end of a four-year research and development project aimed at delivering a ”self-steering capability, called ‘”LASCCM” guidance technology, that will enable a continuous miner (CM) to maintain 3D position, azimuth, horizon, and grade control within a variable seam horizon under remote monitoring and supervision.7
Inertial navigation is again central to the design of LASC-CM. Thus, CSIRO has been working to develop aiding strategies to mitigate the effects of INS time-dependent position drift that will work in the roadway development setting, which is less structured than in longwall mining.
CSIRO’s experimental trial involved modifying a skid steer remote control vehicle so that it mimicked most of the CM dynamics in terms of motion profile, wheel slip, and vibration characteristics. This meant that the technology suite could be tested above ground, on a representative surface, which was important because gaining access to a working mine for extended prototype testing is impractical. The vehicle was fitted with CSIRO’s LASC-CM technology, as well as a high-performance GPS system. This allowed the positioning performance of LASC-CM to be compared with an accurate GPS-derived position.
In the trial, the vehicle was programmed to autonomously mimic the action of a CM developing a two-heading drive with cut-throughs. The practical accuracy of the LASC-CM system is demonstrated in Figure 1, which displays a waypoint during a trial. This and other trials have provided a high level of confidence in CSIRO’s approach.
Importantly, the results obtained show that decimeter 2D position accuracy can be achieved with an INS supported by CSIRO’s combination of aiding strategies over long distances, including sharp turns, reversing, and vibration. CSIRO’s work continues to improve the underlying navigation performance of the LASC-CM system, as well as its deeper system integration.
A field trial of the navigation technology during roadway development at an operating mine has now been completed. In this trial, conventional manual roadway development was carried out according to a mine plan and the position of the continuous miner was logged using CSIRO’s system. Results of the trial are shown in Figure 2. Extremely close agreement was obtained between the mine plan and the measured machine position.
Already the new high-quality miner position information can be used for performance analysis and improvement of existing manual processes. Thus, in the near future, full automation of the process becomes a real possibility because the miner position can be measured robustly with unprecedented accuracy. In a technology transfer process similar to LASC for longwalls, CSIRO will work with leading continuous miner manufacturers on licensing arrangements to deploy the LASC-CM technology commercially.
CSIRO’s research into longwall automation and the subsequent development of commercially available LASC automation technologies have produced clear productivity and safety benefits for longwall mining, and have opened the way to automation of continuous miner operations. Although the basic problems of machine positioning and process control are now close to being solved, barriers to fully autonomous mining operations still remain. Much work remains to be done in machine sensing of the mining environment and consistent automated management of the interaction of the mining process with ground conditions, before the process can be truly autonomous and workers can be removed from underground hazards. CSIRO’s ongoing research is concentrating on resolving these outstanding issues and will contribute significantly to the mining industry’s ultimate goal of zero harm to its people.
- Reid, P.B., Dunn, M.T., Reid, D.C., & Ralston, J.C. (2010). Real-world automation: New capabilities for underground longwall mining. Presented at Australasian Conference on Robotics and Automation (ACRA 2010), Queensland University of Technology, Brisbane, Australia.
- Reid, D.C., Ralston, J.C., Dunn, M.T., & Hainsworth, D.W. (2015). Longwall shearer automation: From research to reality. In J. Billingsley & P. Brett (Eds.), Machine vision and mechatronics in practice (pp. 49–57). Berlin–Heidelberg: Springer.
- Beitler, S., Holm, M., Arndt, T., Mozar, A., Junker, M., & Bohn, C. (2013). State of the art in underground coal mining automation and introduction of a new shield-data-based horizon control approach. SGEM2013 Conference Proceedings, 1, 715–730.
- Ralston, J.C., Reid, D.C., Hargrave, C.O., & Hainsworth, D.W. (2014), Sensing for advancing mining automation capability: A review of underground automation technology development. International Journal of Mining Science and Technology, 24, 305–310.
- Ralston, J.C., & Strange, A.D. (2015). An industrial application of ground penetrating radar for coal mining horizon sensing. International Symposium on Antennas and Propagation (ISAP 2015), Hobart, Australia, pp. 402–405.
- Ralston, J.C., Reid, D.C., Dunn, M.T., & Hainsworth, D.W. (2015). Longwall automation: Delivering enabling technology to achieve safer and more productive underground mining. International Journal of Mining Science and Technology (IJMST), 25, 865–876.
- Reid, D.C., Dunn, M.T., Ralston, J.C., & Reid, P.B. (2011). Current research in the development of a self-steering continuous miner, 22nd World Mining Congress and Expo 2011, Istanbul, pp. 197–202.
The author can be reached at firstname.lastname@example.org
The content in Cornerstone does not necessarily reflect the views of the World Coal Association or its members.
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