Technology News

From the Bureau of Mines, United States Department of the Interior

‘Technology news describes tested developments from Bureau of Mines programs. It is published to encourage the
transfer of this information ta the minerals industry and its application in commercial practice. Mention of company

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No. 453, January 1996

Navigation and Control of Continuous Mining
Systems for Coal Mining

Objective

To provide accurate navigation and control of con-
tinuous mining systems.

Background

The primary focus of the U.S. Bureau of Mines
(USBM) is to make mining safer and more healthful for
mine workers. The USBM rescarch program is developing
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 arca
(the face). Advanced navigation and control technologies
are being developed for underground room-and-pillar and
highwall coal mining that can be applied to commercially
available mining equipment. The technology being de-
veloped uses off-the-shelf components, minimizing the
cffort 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.

Navigation

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 (CM) location at all times. The
navigation system provides information allowing the mining
machine to cut to a predetermined mine plan. For
room-and-pillar mining, entries and crosscuts can be cut to
required dimensions and location. In highwall mining, a

constant rib can be maintained between parallel cuts.
Many different navigation devices have been evaluated in
an effort to identify the best onc for use on the CM's.
‘After much research, the USBM has decided the Honey-
well ring laser gyro,’ (previously known as MAPS (mod-
ular azimuth and positioning system), now known as
HORTA (Honcywell ore recovery and tunneling aid)) to
be the best navigation device for the application (figure 1).
Under a contract with Honeywell, the USBM conducted
many hours of underground testing of this gyro on a CM
while cutting coal? Many accuracy improvements were
made and at the termination of the underground tests, a
complete reevaluation of the gyro and its implementation
for the mining machine control process was performed. A
list of desired improvements including increased accuracy,
sharing of navigation data between multiple computer
systems, simplified navigation data interpretation, and a
simplified user intcrface for operating the gyro, was pre-
pared and cach of the improvements were implemented.
‘The navigation data provided by the gyro includes position
of the mining machine in state plane coordinates (feet);
position of the appendages of the mining machine in state
plane coordinates (feet); heading of the mining machine
(degrees); pitch, roll, and yaw of the machine (degrees);
altitude above sca level, cross-track and along track.

The Control System

Continuous mining machine manufacturers offer radio
or umbilical cord control for their mining equipment. This

Use of specific products is for identification only and does not imply
endorsement by the USBM.

2Sammarco, J. J. Field Bvaluation of the Modular Azimuth and
Positioning System (MAPS) for a Continuous Mining Machine. USBM
IC 9354, 1993, 14 pp.

This document was prepared by the U.S. Bureau of Mines. Neither the United States Government nor any person acting on behalf of the United
States Government assume any liability resulting from the use of the information contained in this document, or warrants that such use be free from

privately owned rights.



provides line-of-sight operation from close proximity to
the machine. Rather than using a radio link, the USBM
developed a ficldbus style of control network based on
BITBUS? standards that allows non-linc-of-sight contro] of
all the mining machine’s moving parts. The control net-
work consists of a microcontroller board on the CM, and
a single microcontroller board in a 19-in rack in the
controt ccnter that attaches to a single board PC that plugs
into a passive PC backplane. The two ends of the controt
network are connected with a twisted pair cable. The
USBM 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 CM, 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 separation of the control
network from the data collection network allows the fastest,
system performance. The third connection between the
CM and the 19-in rack is two twisted-pair cables that
connect the machine-mountcd gyro (HORTA) to a PC
card that is plugged into the 19-in rack-mounted PC
passive backplane. The control network, the data
collection network, and the HORTA, arc cach hosted on
their own 486-class single-board PC mounted in a passive
PC backplane in the 19-in rack. All three single-board
PC's share a common monitor and keyboard using a
video/keyboard switcher. One of the key elements of this
application is the introduction of a shared-memory
box (MEM) and hardware that allow the single-board PC’s
to intercommunicate with cach other through extended
memory. The controller (CONTROLLER) software is
the key clement for providing advanced coal mining opera-
tions, Hy using the data collected from all the CM
sensors and the gyro and by executing commands on the
(CM, the controller is able to do complete coal-cutting
scenarios,

IBITBUS is a standard developed by the INTEL Corp, Beaverton,
R.

An Expanded Control System

Many modules can and have been added to the design.
Each module adds another level of sophistication to the
system. Using this method, the USBM is capable of
adapting its technology to the most primitive or most
sophisticated application, simply by adding the modules
required for the application, Figure 2 shows the system's
capabilities, The visualization system (VISUALIZATION)
uses the collected machine data to provide accurate 3-D
graphic representation of the mining machine and asso-
ciated hardware aad its movements relative to the mine
surroundings, The user's interface permits the operator to
zoom around the scone to vicw any part of the process of
interest. Additionally, top down and side views of the CM
for present and previous cuts can be dynamically displayed.
Software called MINENAV is being developed to provide
navigation information to the CONTROLLER computer
that will execute a completely orchestrated mining plan
from start to finish, using navigation and sensory data.
The simulator application (SIMULATOR), also being de-
veloped, will generate a steady stream of data to all the
computers in the system that corresponds to data that
would normally be provided by the mining machinc
sensors, including the gyro. This will allow studies to be
done without turning on the CM. The haulage aplication
(HAULAGE) will provide for control and monitoring of
whatever haulage system is used in the system. The coal
interface detection application (CID) will provide infor-
mation about the thickness of the coal on the roof and
floor, and can also provide information about the thickness
of a rib of coal, A remote camera system both on and off-
board the machine can provide visual information on any
part of the process that the operator desires.

For More Information

For more information, please contact William
Schiffbauer, U.S. Bureau of Mines, Pittsburgh Rescarch
Center, P.O. Box 18070, Pittsburgh, PA 15236-0070.
Phone: (412) 892-6835. E-mail: henry@silver.usbm.gov
(on Internet).

Figure 2

The expanded control system.