modes. Users can define up to 500
states with actions and conditions to
be met before the next state is entered.
The system is also capable of defining
up to 40 zones along the face for each
of the zone-based parameters. This
allows mine personnel to determine all
possible variations in longwall
operation cycles.
History and technology
behind advanced
automation
Achieving automated horizon control
has long been a goal for the longwall
mining industry. There have been
systems developed for shearers that
use a reference cut in one direction and
extraction to a desired thickness in the
opposite direction. These systems have
been enhanced over time with onboard
calculations that take into account
machine and face angles. This helps
create greater accuracy in actual
extraction parameters, with various
methods of extraction depending on
the cutting sequences being employed
on the face.
At the turn of the century, modern
inertial sensor technology was
introduced to offer accurate
measurement of the face alignment,
horizon angles and pan profiles of
longwall faces. Originally derived
from gyroscope technology, inertial
sensor developments became a focus
for Bucyrus and DBT Group, both of
which were subsequently purchased
by Caterpillar. The inertial sensor
technology now used by Caterpillar
has been developed by a third party
supplier, while the associated software
was developed by Caterpillar over the
past 14 yr.
The company’s proprietary system
has been continually improved since
its implementation and saw
improvements to the software,
hardware and monitoring systems
with integration into the Caterpillar
visualisation suite of programmes as
part of Cat MineStar Health.
Hardware
Caterpillar offers two inertial sensors
to use as inertial measuring units
(IMUs). These units have proven their
capabilities in underground longwall
mines in Australia. They are classified
by accuracy, the ability to detect north
and the ability to process data
onboard. Each unit is configured to
operate within the system, while
customers choose whichever unit best
meets their needs.
Software
As part of the Navigator system, there
is a processor (IPC) on the shearer to
collect, process, calculate and
communicate data within the shearer
EIP control system, as well as both to
and from the gate end computer. Face
and horizon profiles are generated by
the IMU, through the IPC to the
visualisation software (VShearer, part
of Health for Longwall) at the gate
end. With this system, there is no
need to transfer data to a surface
server for processing, while all
communications are carried out
between the shearer and gate end
visualisation PC.
The ranging arm and shearer
positions are calculated by the
programmable logic controller (PLC).
The IPC performs the automated
steering (including state automation)
and sends haulage and ranging arm
commands back to the PLC.
Accuracy
The latest information received from
an advanced automation control
longwall operation in
New South Wales, Australia, shows
that accuracy has been measured to
within 50 mm. The original target was
to be accurate to within 75 mm;
however, some enhancements to the
software have resulted in greater
accuracy.
The graphic in Figure 4 shows the
change in the profiles over three
months during implementation of
shearer automation at a mine site. The
degree of automation was increased in
two steps and the period of manual
override constantly reduced.
Table 3. Advanced Automation Control: the highest level of automation functions for a longwall shearer
Advanced automation
control
Basic automation 1+
Advanced automation of high accuracy using inertion navigation: PLC, IPC and
INU (accuarcy < 20 mm along the machine length)
Advanced geometry/trigonometry For 3D navigation
Floor profile/arm algorithms
For 3D navigation
Interface to longwall
navigator/landmark
Enables integration of third party navigation system with landmark interface
Figure 2. Horizon control, extraction control and face alignment are the main features
provided by Cat LongwallNavigator.
54
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World Coal
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August 2015
