Table 2.—Lasernet tracking and tram control accuracy

Measurement Lasernet
Tram maneuver translation, in error, in
Transit_Lasernet_ Tracking Control
Tram reverse 40 in . 38.36 38.25 O11 1.64
Tram forward 36 in . 3261 32.54 07 3.39
Tram reverse 40 in . 41.70 41.69 01 -1.70
Tram forward 36 in . 38.70 38.65
Tram reverse 38 in . 38. ;
Me
rotation, deg error, deg
Transit. Lasemet Tracking Control
Pivot right 15° 13.10 1283 027 19
Pivot left 12° 11.43 11.20 23 (87
Pivot right 15: 13.04 12.52 52 1.96
Pivot left 15° . » 1471 14.10 ne)
Turn reverse right 10° .. 10.67 10.43, 24-87
Turn forward left 10° 10.23 9.86 37-23
Turn forward left 7°. 692 6.78 1408
Pivot left 10° 994 977 A706

SUPPORTING EXPERIMENTS

Related underground experiments on computer-assisted
mining systems used the Lasernet system for its ability to
track and control the tramming of the continuous miner.
The Lasernet system was an integral part of two experi-
ments to test the first fully controlled, automatic execution
of multiple sump-shear cutting cycles. The first experi-
ment used a preprogrammed coal removal script created
and executed via the autonomous mining research and
development system (AMREDS) (5). The second experi-
ment used Carnegie-Mellon University’s continuous miner
navigation system (MINENAV) software to dynamically
plan the maneuvers and appendage commands necessary
during a two-pass mining sequence.

The first experiment was an automatic execution of
sump-shear cycles via a preprogrammed script of fully con-
trolled continuous miner functions. It used Lasernet to
control translational distances of the continuous miner,
and AMREDS to create and execute the script of machine
commands for coal removal.

The script contained a sequence of continuous miner
functions typically used during two successive sump-shear
cycles, The script used closed-loop appendage commands,
via the continuous miner control computer, and closed-
loop tram commands, via the Lasernet system. During
execution, AMREDS’ script executor followed the script
and sent the commands to the appropriate node on the
BITBUS network upon successful completion of the pre-
vious command in the script.

The experiment initially took place with the Joy 16CM.
cutting coalcrete in the METF, and then with the Joy
14CM cutting coal underground. In the underground
experiment, seven scripts ran in sequence with human
involvement limited to pauses to let the shuttle car empty
and to issue the script start command. Each sump dis-
tance was fixed at 22 in. Table 3 shows the accuracy in
which the Lasernet system controlled the sump distance,
and also the rate at which the sump was performed, The
average error in sump distance was 0.76 in, and the
average sump rate was 1.1 in/s.

Table 3.—Tram control and rate during sump

Distance traveled, in Error, in Sump rate, in/s
22.35 .. 0.35 1.54
23.06 1.06 127
21.88 112 1.58
21.20 80 90
21.42 -58 87
21.08 -92 76
21.42 -58 1.61
20.28 1.72 1.12
21.28 72 80
21.17 -.83 55

A second experiment tested MINENAV software for
dynamic planning and execution of a two-pass mining
sequence. The MINENAV software includes algorithms
for controlling the continuous miner’s maneuvering in
mine rooms and its appendages while executing a two-pass
(box and slab cut) mining sequence. It used the Lasernet
system for both tracking XYH and controlling the tram
maneuvers of the continuous miner. Lasernet data also
characterized the Joy 14CM’s tram velocities underground
for use by MINENAV.

Using Lasernet XYH updates and controlled trans-
lational and rotational maneuvers, MINENAV successfully
maneuvered the Joy 16CM through the transition from the
box to slab cut. Researchers tested the maneuvering and
appendage control required for the actual coal cutting
sequence. MINENAV demonstrated the ability to move
the Joy 16CM through free space, square up to the
coalcrete, and perform a sump-shear cycle in coalcrete.

Researchers performed these same experiments
underground with the Joy 14CM. They conducted many
successful repetitions of the Joy 14CM maneuvering within
a mine room and squaring up to the face, and executed
several sump-shear cycles.


deg

ft

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT

ampere MHz
degree mV
foot mW
inch 1/s
inch per second Vac
pound Vde

megabyte w

megahertz

millivolt

milliwatt

revolution per second
volt, alternating current
volt, direct current

watt



Figure 4.—Experimental setup at Bureau of Mines test facility.
sensors on tripods.

to prevent lens fogging and heat buildup; internal shock
and vibration mounts to protect the Lasernet sensor; and
a top lens window to allow sighting of the optical center-
line of the unit for calibration. The power and RS-485
data communication cables exit the enclosure through a
packing gland and connect to the Lasernet power supply
junction box.

The Lasernet power supply junction box (fig. 6) permits
multiple Lasernet sensor connections within the sensor
network, The junction box is a standard explosion-proof
control box, manufactured by MCI, with internal mod-
ifications to Bureau specifications. The junction box is
steel construction weighing 60 Ib and is movable inby with
the Lasernet guidance system, Main power 115 V ac cir-
cuit interrupting devices, power control, and electro-
magnetic interference (EMI) filtering are incorporated into
the junction box to comply with MSHA’s certification
requirements.

The junction box includes a LAMBDA LDS-P-24 linear
power supply, which has a maximum of 9 A output at +24
V de, less than 1 mV ripple, and an input rating of 108 to

e a
Retroreflective targets on Joy 16CM continuous miner and Lasernet

127 V ac, 475 W. Power supply derating to +24 V de,
4.5 A within the enclosure permits ample heat dissipation
and cooling for continuous operation. Direct-current (dc)
power distribution fusing and line terminations to each
Lasernet sensor permit five sensors to be connected. Data
line conditioning fuses protect RS-485 data lines within the
junction box. The de power and signal cable to each
Lasernet sensor is limited to 50 to 100 ft from the junction
box to minimize line losses. The input alternating current
(ac) power and signal enter the junction box through
500 ft of cabling within conduit from the outby Lasernet
interface unit (LNI).

LASERNET INTERFACE UNIT

The LNI (fig. 7) is a standard 5-1/2- by 19-in rack-
mounted portable interface unit. The LNI provides power
control, and contains a Lasernet interface controller card
and BITBUS network interface hardware. A Lasernet
interface controller card converts RS-485 communications
to RS-232 data format for connection to an RS-232 serial


INTRODUCTION

The U.S. Bureau of Mines is developing the technology
for computer-assisted mining systems to increase the
health and safety of mine workers and to improve recovery
of coal (1)? Current research focuses on sensor and
computer technologies necessary for computer-assisted,
remotely supervised operation of a continuous mining ma-
chine as it performs two-pass room-and-pillar-type mining,
These new technologies will improve worker health and
safety by relocating workers from the hazardous working

face to a remote, sheltered underground control station.
Coal recovery will increase as a greater percentage of
minable coal is removed, and more time is spent on pro-
duction and less on machine idle time.

Reliable and accurate guidance of a continuous mining
machine is essential for computer-assisted operation. This
report describes a laser-based underground guidance sys-
tem to track and control the tram maneuvers of a continu-
ous mining machine.

SYSTEM DESCRIPTION

The system uses four Lasernet® laser-scanning sensors
that report the angular coordinates of two retroreflective
targets. The lasers are mounted on two poles located at
fixed positions on both sides of the entryway, 25 to 30 ft

Italic numbers in parentheses refer to items in the list of references
at the end of this report.

Reference to specific products does not imply endorsement by the
U.S. Bureau of Mines.

outby the face. Retroreflective targets are mounted on the
tail end of the continuous mining machine (fig. 1).

A real-time microcomputer system requests and proc-
esses the angular coordinate information from each
Lasernet sensor and does the trigonometry necessary to
determine the continuous miner’s position and heading (2).
The microcomputer also executes and controls transla-
tional and rotational tram maneuvers,

Figure 1.Conceptual drawing of Lasernet guidance system with targets on continuous min-
er and lasernet sensors in entryway.


UNDERGROUND TEST RESULTS OF A LASER-BASED TRAM
CONTROL SYSTEM FOR A CONTINUOUS MINER

By Donna Lynne Anderson’

ABSTRACT

This report documents the status of a laser-based underground guidance system for tracking and
controlling the movements of underground mobile mining equipment. This research is part of a multiple
project effort at the U.S. Bureau of Mines to increase mine safety and efficiency by developing tech-
nology for computer-assisted mining. Guidance systems, which can track and control the movements
of underground mining equipment, are essential during computer-assisted mining operations, A con-
tinuous mining machine at the Bureau’s surface test facility served as the test-bed for initial development
and experimentation of this guidance system. Subsequently, a continuous mining machine in an
underground mine served as the platform for in-mine experimentation.

The first section of this report includes details of the laser sensors, communication network, and
computer hardware. The next section includes experimental results, which show the system capable of
accurately tracking and controlling the tram maneuvers of a continuous miner underground. The final
section discusses conclusions and recommendations.

‘Blectrical engineer, Pittsburgh Research Center, U.S. Bureau of Mines, Pittsburgh, PA.


and are housed in permissible, explosion-proof enclosures.
A remote control station houses the outby components. A
communications and power cable allow a 500-ft separation
between the working face and the control station.

LN-120 LASERNET SENSORS.

The laser scanner used in the system is the LN-120/
40001 Lasernet (fig. 3), developed by Namco Controls,
Mentor, OH. Lasernet directs an eye-safe class 2 laser
light source at a rotating mirror. The mirror sweeps a
horizontal beam of laser light out the front window of the
unit at a constant angular speed of 20 r/s.

The LN-120 model incorporates a 2.0-mW laser tube.
It detects targets out to a 35-ft range and has an angular
field-of-view of 110°. The targets are retroreflective tape
attached to 10-in-diameter, 18-in-tall cylinders. When the
Lasernet’s beam crosses a target, the beam reflects back
to the unit and is detected by a photodetector. A micro-
controller in the unit processes the information from the
photodetector and determines a raw angle count (RAC),

CLASS 2 LASER W apra;
MIE Dow SE

Figure 3.LN-120 Lasernet laser-scanning sensor.

which is proportional to the angular coordinate of the
target. The unit returns the RAC’s for all targets in its
field-of-view upon request from the host computer on a
serial data line.

Extensive tests at the Bureau showed the angular coor-
dinate reports from the LN-120 Lasernet to be accurate to
+0.3°. The accuracy improved to less than +0.1° after
correction of repeatable errors (4).

During experimentation at the METF, the Lasernet
sensors were mounted on two tripods located at fixed po-
sitions on both sides of a mock entryway. Figure 4 shows
the setup at the METF. During underground experimen-
tation, the Lasernet sensors were housed in explosion-
proof enclosures and mounted on two poles. The poles
were at fixed positions on both sides of the entryway, 25 to
30 ft outby the face. Two retroreflective targets were
mounted on the tail end of the continuous mining
machine,

RS-485 COMMUNICATION NETWORK

The host computer requests and receives raw angular
coordinate data from the Lasernet units over an RS-485
communication network, RS-485 uses two-wire balanced
differential signals. The longer transmission lines and
increased noise tolerance suit underground use. RS-485
also supports multidrop features, which allows all four
Lasernet units to be attached to common send and receive
lines. Therefore, the microcomputer system requires a
single RS-232 serial port, which is tied into the RS-485
network via a Lasernet interface controller.

Each Lasernet unit on the network has a unique com-
munications address included in the request for data. The
microcomputer issues a request for data via a serial port.
The Lasernet interface controller converts the data to RS-
485 format. All units on the RS-485 network receive the
request, but only the unit specifically addressed will
respond.

EXPLOSION-PROOF HOUSING

The Bureau designed an explosion-proof enclosure
(fig. 5) to house the Lasernet sensor for underground
experiments. The enclosure is 1/2-in aluminum, welded
construction, Mining Controls Inc. (MCI), Beckley, WV,
fabricated the enclosure, and the Mine Safety and Health
Administration (MSHA) certified it explosion proof. The
lightweight enclosure design enables quick and easy posi-
tioning. The Lasernet enclosure includes the following
features: a frontal lens window made of 1/2- by 2- by
7-1/2-in boro-sylicate glass to allow the full 110° field-of-
view; a frontal lens tilt of 12° to prevent lens reflections
from causing damage to the Lasernet’s photodetector; an
Appleton breather plug on the explosion-proof enclosure


RI} 9440 REPORT OF INVESTIGATIONS/1992

Underground Test Results of a Laser-Based
Tram Control System for a Continuous Miner

By Donna Lynne Anderson

UNITED STATES DEPARTMENT OF THE INTERIOR Bee

BUREAU OF MINES _


system. During software development, the Heurikon-
VxWorks communicates across Ethernet to a Sun work-
station, Editing, compiling, linking, and managing files
of the real-time software occur on the Sun workstation.
However, before testing, the software is downloaded to the
Heurikon-VxWorks system across Ethernet. The benefits
of using the Heurikon-VxWorks system as opposed to the
Sun-UNIX are the implementation of faster and more effi-
cient real-time programming techniques and portability for
in-mine use.

SOFTWARE OVERVIEW

The software for the Lasernet tram control system is a
multiprogrammed system consisting of several computa-
tional and input-output modules. The primary modules
include the tracker, the BITBUS data request handler, and
the closed-loop tram handler. Figure 9 shows a data flow
diagram of these three modules.

The tracker reads data from the Lasernet sensors and
places the new position and heading of the continuous
miner in a common data store. Updates are calculated as
often as five times per second. The closed-loop tram han-
dler accepts tram requests from external devices across the
BITBUS network, monitors the updates from the data
store, and initiates and controls tram executions. The
BITBUS data request handler accepts data requests from
external systems on the BITBUS network and delivers the
position and heading updates from the data store to the
requesting node on the BITBUS network.

Other modules include a system initialization rou-
tine that creates a system data base at startup time. This

User
7 cied-toop
rom. requests Momentary
Tram tram commends [| BITBUS
acknowledgements aiTaus
ecknonlsdgenen's ba y
requests
Date
poutn Position and Bireus ~~ "sponses
heading” updotes data request
and heading Ha reaue
‘doles
New postion
tnd heading,
Postion ond
heading updates:

Figure 9.—Data flow among primary software modules.

Lasernet

routine makes the system easily reconfigurable to suit
different guidance tasks. For example, if the operator
chose to move the Lasernet unit to another location in the
entry, then he or she would enter a new coordinate in the
data file, and reinitialize the system, resulting in no
reprogramming or recompilation of the software. Also, if
a Lasernet unit was removed from the system, then the
operator would only enter a new identification address for
the replacement unit.

The final feature is a logging facility to collect data
during tram experiments. It collects, time stamps, and
stores position and heading data to a data file.

EXPERIMENTAL RESULTS

Researchers first took the Lasernet guidance system
underground for experimentation in early 1991. The
following sections entitled "Reliability" and "Tracking and
Tram Control Accuracy” give the experimental results.
Underground experiments involving other computer-
assisted mining systems used the Lasernet system to
measure tram rates and to track and control the tramming
of the continuous miner. To demonstrate potential uses of
Lasernet, the "Supporting Experiments" section describes
the Lasernet system’s involvement in these experiments.

RELIABILITY

The most crucial factor in maintaining the Lasernet
guidance system’s reliability is keeping the targets in the
lasers’ view. The lasers have a 110° field-of-view, which
easily sweeps the entire entryway. However, the Lasernet
sensor has a limited 35-ft target detection range, which

reduces the flexibility of the system. It is easy to tailor the
experiments to stay within the range; however, for more
extensive and practical use of the system, another version
of the Lasernet sensor is recommended. Extended-range
Lasernet sensors with a 100-ft target detection range have
become available since the initial development of this
system.

Researchers found another difficulty affecting system
reliability during the first experiment. Continuous miner
position and heading updates became unavailable when the
laser’s scanning beam did not cross the targets, ie., the
beam actually scanned above or below the surface of the
target. The situation was caused by an unusually irregular
floor.

Taller targets increased the vertical tolerance from 14
to 18 in, In addition, two Lasernet units were added to
the system. These two Lasernet sensors are mounted 6 to
12 in higher than the original two sensors (fig. 10). With


sor.

Figure 6.—Explosion-proof housing for power supply junction
box.

Figure 7.LNI Lasernet interface unit.

port on the microcomputer. A BITBUS network interface
card and a transient protection module provide a gateway
into the BITBUS network from a second serial port on the
microcomputer system. Finally, the LNI contains two
power supplies: a LAMBDA linear supply with +24 V at
3A, and a LAMBDA triple output switching power supply
with +12 V de at 1.2 A, -12 V de at 0.5 A, and +5 V de
at 8A.

During underground experimentation, the LNI is lo-
cated with the microcomputer system outby the operating
face in fresh air.

HEURIKON VXS/V2E MICROCOMPUTER

The Heurikon VXS/V2E real-time microcomputer sys-
tem (fig. 8) processes the Lasernet data, tracks the
position and heading, controls the tramming, and handles
data requests for the continuous miner. It includes a
powerful 32-bit single-board computer that runs VxWorks,
a real-time UNIX compatible operating system, The com-
puter includes a 20-MHz 68020-based central processing
unit (CPU) board, an Ethernet controller, a 20-MHz
68882 floating-point coprocessor, four serial input-output
(L-0) ports, and 4 MB of memory.

The Heurikon-VxWorks system works with the Sun
3-160-UNIX environment. The Sun-UNIX environment
provides a high-level software development platform for
real-time code development and file management, The
Heurikon-VxWorks system provides a platform to run,
test, and debug the software for the Lasernet guidance

Figure 8—Heurikon VXS/V2E real-time microcomputer system
for tracking and controlling Joy 14CM tramming.


CONTINUOUS MINER TEST-BEDS

A Joy 16CM continuous mining machine at the Bu-
reau’s mine equipment test facility (METF) served as the
test-bed for initial development and experimentation of the
guidance system. The METF also houses a 6-ft-high block
of coalcrete, which is a mixture of concrete, flyash, and
coal used for testing coal removal operations. A Joy
14CM, in an underground coal mine in West Virginia,
served as the platform for in-mine experimentation. Pre-
liminary experiments, run on the Joy 16CM in the METF,
helped to prepare for experiments underground on the Joy
14CM.

Both the Joy 16CM and the Joy 14CM were outfitted
with sensors for appendage movement of the machines’
parts, electrical system voltages and currents, and hydrau-
lic system pressure, temperature, and debris. These
sensors, along with the continuous miner hydraulic control
valves, tram relays, and other electrically actuated control
functions, have been interfaced to a computer. The com-
puter connects to and communicates across the Intel

BITBUS distributed control network via a BITBUS node.
The BITBUS network supports communications among
16 BITBUS nodes, thereby allowing other computerized
mining systems residing on external devices to connect to
anode and obtain access to the continuous miner’s sensors
and functions. The BOMNET protocol, developed by the
Bureau, sets the standards for communications between
external devices and the BITBUS (3).

The BITBUS network and BOMNET protocol let the
Lasernet guidance system easily issue tram start and stop
commands. The microcomputer system simply writes the
appropriate BOMNET protocol packets to a serial port,
which is connected to a BITBUS node, designated as
node 3. When the continuous miner computer (node 1)
receives a tram command packet, it activates the appro-
priate tram relays. Similarly, the Lasernet guidance system
can issue a command to deactivate the tram relays. In this
manner, the Lasernet guidance system effects tram control
on the Joy 14CM and the Joy 16CM.

GUIDANCE SYSTEM COMPONENTS

Figure 2 shows the major system components used for
in-mine testing and evaluating of the Lasernet guidance

system. Allinby components of the guidance system oper-
ate near the continuous miner in the working face area

Laser
enclosure Laser
Microcom- —— ‘
puter system RS-232 power ond
data link data ——+
Laser 50
interface BITBUS ft Ll
unit data link oer
Power Explosion ~ proof EO -—4 To
500 ft power retroreflective
L___ 1-4 supply junction F— targets on
Rs-485 ! | box continuous
datalink; =| Laser mining machine
i I 3
| I |
|
i
i |
I | Laser
ot 4
ot
1 1
I ot
io
iot
1 |
1
Outby i} Ll Inby
equipment equipment

Figure 2.—System components for in-mine experiments.


CONTENTS

Abstract .....
Introduction .
System description .
Continuous miner test-beds .
Guidance system components
LN-120 Lasernet sensors .
RS-485 communication network .
Explosion-proof housing .
Lasernet interface unit :
Heurikon VXS/V2E microcomputer .
Software overview ...
Experimental results ..
Reliability
Tracking and tram control accuracy .
Supporting experiments .
Conclusions .
References . .

ILLUSTRATIONS

Conceptual drawing of Lasernet guidance system .
System components for in-mine experiments .
LN-120 Lasernet laser-scanning sensor .....
Experimental setup at Bureau of Mines test facility
Explosion-proof housing for LN-120 Lasernet sensor .
Explosion-proof housing for power supply junction box .
LNI Lasernet interface unit . .
Heurikon VXS/V2E real-time microcomputer system
Data flow among primary software modules .
Two Lasernet sensors mounted at different heights . .

Seer aAvayne
WIARAAUAWN

an

TABLES

r

Lasernet tracking accuracy
2. Lasernet tracking and tram control accuracy .
Tram control and rate during sump

© 00

bad



10

CONCLUSIONS

This report described the Lasernet guidance system for
tracking and controlling the movements of underground
mobile mining equipment. The system was developed and
tested at the Bureau’s mine equipment test facility on a
Joy 16CM continuous miner and in an underground mine
on a Joy 14CM continuous miner.

The system successfully and accurately tracked and
controlled the tram maneuvers of a continuous miner
underground. It employs off-board laser-scanning sensors
to report the angular coordinates of retroreflective targets
on the continuous mining machine. A real-time micro-
computer processes the angular coordinates, calculates
position and heading, and controls tram maneuvers of the
continuous mining machine.

Results of the underground experiments are promising.
The system tracks the position of the continuous miner to
an accuracy of less than 1 in, and the heading to less than
0.5°. Tram control accuracies are less than 4 in transla-
tion, and less than 2° rotation.

The most crucial factor in maintaining the reliability of
the system is keeping the targets in the lasers’ view. For

more extensive and practical use of the system, an extend-
ed range Lasernet sensor is recommended. These sensors
have a target detection range of 100 ft, thus greatly
increasing the flexibility of the system. Vertical tolerance
was also a problem during one experiment on an unusual-
ly irregular floor. The employment of taller targets and
additional sensors at different heights increased the ver-
tical tolerance to 30 in and resulted in much less difficulty
in keeping the targets in the lasers’ view. For more exten-
sive use, a mechanical device for vertically sweeping the
beam could be added to the sensor to better resolve the
problem.

The Lasernet guidance system could be applied to other
mining equipment, ie., shuttle cars, roof bolters. Simple
alterations to software could make the system capable of
tracking any vehicle with retroreflective targets. Addi-
tionally, the Lasernet system could control tram maneuvers
of any mining vehicle equipped with a communications
interface to electrically actuated tramming functions.

REFERENCES

1. Schnakenberg, G. H., Jr., and J. J. Sammarco. Overview of the
ULS. Bureau of Mines Computer-Assisted Mining Research Program.
Paper in Proceedings of the International Symposium on Mine Mech-
anization and Automation. CO Sch. Mines, Golden, CO, v. 2, 1991,
pp. 9-29.

2. Anderson, D. L. Position and Heading Determination of a
Continuous Mining Machine Using an Angular Position-Sensing System.
BuMines IC 9222, 1989, 8 pp.

3. Schiffbauer, W. H. A Microcomputer Network for Mining Ma-
chine Control. Paper in Proceedings of the Tenth WVU International

Mining Electrotechnology Conference. WV Univ., Morgantown, WV,
1990, pp. 928-935.

4, Anderson, D. L., and J. S. Gbruoski. A Laser-Based Continuous
Miner Guidance System. BuMines IC 9288, 1991, 14 pp.

5. Ausefski, D. B. Researcher's Interface Software for Computer-
Based Mining System Development and Testing. Paper in Proceedings
of the Tenth WVU International Mining Electrotechnology Conference.
WV Univ., Morgantown, WV, 1990, pp. 130-133.



Library of Congress Cataloging in Publication Data:

Anderson, Donna Lynne
Underground test results of a laser-based tram control system for a continuous
miner / by Donna Lynne Anderson.
p. cm. — (Report of investigations; 9440)
Includes bibliographical references (p. 10).
Supt. of Docs. no.: I 28.23:9440.
1, Mining machinery—Automatic control. 2. Mine railroads—Automatic control.

3. Lasers in navigation. I. Title. II. Series: Report of investigations (United
States. Bureau of Mines); 9440.

TN23.U43  [TN345]_ 622 s—de20 [622] 92-5712 CIP



Report of Investigations 9440

Underground Test Results of a Laser-Based
Tram Control System for a Continuous Miner

By Donna Lynne Anderson

UNITED STATES DEPARTMENT OF THE INTERIOR
Manuel Lujan, Jr., Secretary

BUREAU OF MINES
T S Ary, Director


es N
Figure 10.—Two Lasernet sensors mounted at different
heights to aid target detection on Irregular mine floors.

<.

the two additional sensors and 18-in-tall targets, the ver-
tical tolerance of the system increased from 14 to 30 in.
Further underground experiments showed few problems
due to vertical intolerance.

TRACKING AND TRAM CONTROL ACCURACY

Researchers accumulated data to determine the Laser-
net system’s accuracy in tracking the position and heading

and controlling the tram maneuvers of the Joy 14CM both
at the METF and underground. The goal for a computer-
assisted guidance system is to guide the continuous miner
through the advancement of a 20-ft cut with less than a
6-in-lateral deviation from the mine plan. A tracking and
control system would require a heading accuracy to bet-
ter than 14° (6 in. in 20 ft), The following results of
the tracking and tram control experiments show promise
toward attaining this goal.

The first experiment showed the accuracy in tracking
the position and heading of the continuous miner as it
performed a variety of maneuvers underground, After
each move, a transit reading verified the XY position and
heading (H) of the continuous miner. Table 1 shows some
of the transit readings compared with Lasernet XYH.
Average errors were heading, 0.4°; X position, 0.65 in; and
Y position, 0.2 in.

The second experiment shows the accuracy in tracking
and controlling the translations and rotations of the
continuous miner. Table 2 shows the results of these tests.
The first column shows the desired tram maneuver. The
second column shows the actual translation or rotation of
the continuous miner, which was calculated using two
transit measurements taken before and after the maneu-
ver. The third column shows the translation or rotation
measured by the Lasernet system. The final columns show
errors that demonstrate the Lasernet accuracy in meas-
uring and controlling translation and rotation. Average
measurement errors were 0.62 in translation, 0.32° rota-
tion. Average control errors were 2.05 in translation, 0.72°
rotation,

Table 1.—Lasernet tracking accuracy

Transit Lasernet Error

Xft Y, ft H, deg Xft Y, ft Hdeg Xin Y, in

1.026 64.940 2.382 «0.977 «64.928 0.198 0.585 (0.143

863 «61.747 2.977 857 61.743 032 081 048

1.002 64.461 -3.036 969 64,452 =188 405 109

839 60.990 -3.290 814 60.981 -.081 293 101

1.019 64.210 -3.076 945 64,199 295 885 131

1106 64.573 -15.907 995 64.564 +559 1.331 106

1.177 64.506 4710 1.083 64.495 3322 1.122 136

1177 64.762 “17.2381 1,080 64.753 ~842 1.762 An

1.258 64.700 3.131 1.206 64.693 7-235 626 .087

14.036 1.196 64.028 13.560 1.113 64.029 -A76 997 017
3.805 1.287 64.796 3.700 1.284 64.758 -.105 .032 453
10.721 1.405 65.855 10.483 1.368 = 65.833 -.237 450 270
10.157 900 62.661 9.831 831 62.650 -326 821 131
215 1.043 62.599 059 1.006 62.591 -156 445, .094

1H Heading of the continuous mining machine.

XY Positions of the continuous mining machine.