Research conducted at the Pittsburgh Research Center (formerly U.S. Bureau of Mines) developed technology that will allow computer-assisted operation of mechanized equipment normally used in underground room-and-pillar coal mining, while permitting workers to be located away from the hazardous coal extraction area (the face). Advanced navigation and control technologies developed for underground room-and-pillar and highwall coal mining can be applied to commercially available mining equipment. The technology being developed uses off-the-shelf components, minimizing the effort required to adapt it to mining equipment. Because the new developments are completely modular, only the modules required in a particular application need be used on the system.

The most important requirement for a computer-assisted mining system is an accurate, reliable navigation system that is mounted on the mining machine to provide the continuous miner's location at all times. The navigation system provides information allowing the machine to cut to a predetermined mine plan. Many different navigation devices were evaluated in an effort to identify the best one for use on the machine. The Honeywell ring laser gyro known as HORTA was selected as the best navigation device for the application. The data provided by the gyro includes position of the machine in state plane coordinates (feet); position of the appendages of the mining machine in state plane coordinates; heading of the mining machine (degrees); pitch, roll, and yaw of the machine (degrees); altitude above sea level, cross-track and along track.

The Expanded Control System.

Investigators developed a fieldbus style of control network based on BITBUS standards that allows non-line-of-sight control of all the mining machine's moving parts. The control network consists of a microcontroller board in a 19-in. rack in the control center that attaches to a single-board PC plugged into a passive PC backplane. The two ends of the control network are connected with a twisted cable pair. The network uses a second fieldbus network to provide data collection of the positions of all the moving parts of the mining machine, as well as the status of the machine's critical parameters, such as motor currents, hydraulics, pressures, temperatures, and other relevant parameters. This network consists of sensors, signal conditioning modules, and a microcontroller board on the continuous miner, and a PC card that plugs into a passive PC backplane in the 19-in. rack. The two ends of the data network are connected with a twisted-pair cable. The third connection between the machine and the 19-in. rack is two twisted-pair cables that connect the machine-mounted gyro to a PC card that is plugged into the PC passive backplane. The controller software is the key element for providing advanced mining operations. By using the data collected from all the continuous miner's sensors and the gyro and by executing commands on the miner, the controller is able to do complete coal-cutting scenarios.

Many modules can and have been added to the design. Each module adds another level of sophistication to the system. Using this method, the technology is capable of adapting to the most primitive or most sophisticated application, simply by adding the modules required for the application. The figure at right shows the system's capabilities. The visualization system uses the collected machine data to provide accurate 3D graphic representation of the mining machine and associated hardware and its movements. Software called Minenav is being developed to provide navigation to the controller computer that will execute a completely orchestrated mining plan from start to finish, using navigation and sensor data. The coal interface detection application (CID) will provide information about the thickness of the coal on the roof and floor, and can also provide information about the thickness of a rib of coal.

This work was done by William H. Schiffbauer of the National Institute for Occupational Safety and Health. For further information, contact Schiffbauer at NIOSH, Pittsburgh Research Center, PO Box 18070, Pittsburgh, PA 15236-0070; (412) 892-6835; E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. (on Internet).

Motion Control Tech Briefs Magazine

This article first appeared in the June, 1998 issue of Motion Control Tech Briefs Magazine.

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