When we turn up the heat during the winter, most of us give little thought to the coal mining industry. Images of Kentucky coal miners with blackened faces may come to mind – images that are surely out of date. But most of us have no modern images to replace those with.
Here’s a new image to replace the old one: Picture a 90 ton, 50 foot long automated Coal Shearing machine that eats its way through layers of coal underground. In coal strata* the machine moves at a rate of 50+ feet per minute, doing the work of thousands of coal miners with unstoppable force.
Such is the state of the art in underground automation equipment. A world which is experiencing a transformation similar to that of factory automation and process control: Open standards are relentlessly marching forward, propelled by expectations of network communication and interoperability.
David Reid is the Senior Research Engineer for CSIRO Exploration and Mining at the Queensland Centre for Advanced Technologies in Australia. David is leading the charge to standardize the controls of these machines, and the protocol he has chosen is EtherNet/IP.
Reid says, “As part of the Longwall automation project, we are also introducing enabling technologies, most notably a high-end military-grade inertial navigation system and ruggedized wireless Ethernet gear.”
The underground mining environment is incredibly harsh and hostile. The application of even standard technology is a major undertaking and consequently, the mining industry tends to lag behind the general industry in technology adoption. As an indication of the harsh and difficult environment, the inertial navigation system must be located on the moving shearer in a metal constructed from welded sections of solid metal plate, up to 35mm in thickness which is then welded/bolted to the shearer.
“We needed a communications and control standard that would achieve interoperability between the existing and new equipment and would meet the coal mining industry’s requirements for a non-proprietary open system – i.e., no black boxes.”
Condition monitoring will collect vibration data, which involves large file transfers. Not only does the system have the usual hard-wired Ethernet, but CSIRO also plans to incorporate wireless Ethernet for broadband communications with the moving shearer. Radio waves can withstand the brutal environment better than cables can.
Reid says, “Because the team is working with well-known equipment, there was the temptation to go for a home-spun simple protocol in TCP/IP. We avoided that because of our desire to keep the system open, expandable and maintainable for the future. The CIP component (Control and Information Protocol) is well proven in DeviceNet, and the specifications are publicly available and supported.”
The project (known as the Landmark project) is funded by Australia’s coal mining industry and the technology being developed must be applicable across of mix of mining equipment from a number of manufacturers. That was the motivation for EtherNet/IP. Existing mining machine designs don’t have a common communication interface. EtherNet/IP (EIP) makes that possible. EIP was chosen over other protocols for the following reasons:
The Landmark project calls for a central process controller that acts as a central EIP client. Existing Longwall devices will be EIP servers, including the shearer and roof support systems; plus the inertial navigation system, which is mounted on the shearer. The navigation system accurately tracks the position of shearer in all three dimensions as it moves.
The Landmark project comprises six major components and will be implemented over a three year period:
The project components are functionally separate but are common at the device and control system level. To achieve the goal of system openness and component interoperability it is necessary to define a control and communication specification for Landmark compliant equipment that is generally applicable across the six components.
The type of devices and data are specific to each component. For example, for automated Face Alignment, the primary sensor is the inertial navigation system and the primary actuator is the roof support system. In the Face Alignment control loop, data from the inertial navigation system is stored and processed and position correction information is fed to the roof support system. Closed loop control is maintained by the roof support system, which adjusts the path of the shearer to achieve the desired face alignment.
Once CSIRO decided on EtherNet/IP, and given a tight time frame for the project, the team realized that a lot could be gained by getting an off-the-shelf software stack from someone with in-depth knowledge of the protocol.
Real Time Automation provided an EIP stack which fast-tracked the development. Consisting of only two threads, RTA’s stack was clearly easy to implement, could be quickly ported to multiple operating systems and hardware platforms, and had the necessary features.
*The coal lies on a well-formed seam and so there is usually a distinct boundary between the coal and the underlying or overlying strata. The operators try and keep the shearer within the coal seam always as shearing outside the seam (into rock, sandstone, mudstone, shale etc.) can quickly damage the shearer.
Visit the Landmark Longwall Automation website here.
Additional general information about the longwall mining process can be found here. This site includes downloadable videos and details on equipment and devices.
Additional information on EtherNet/IP can be found in the following whitepaper:
“The Everyman’s Guide to EtherNet/IP” by John S. Rinaldi is available on Amazon.com.