CONTROLLING A THIN-SEAM MINER 500 FEET FROM THE FACE 

August J. Kwi towski 

William H. Schiffbauer 

William D. Mayercheck 

Pittsburgh Research Center 

U.S. Department of the Interior, Pittsburgh PA 

ABSTRACT 

This report summarizes work sponsored by 

the Bureau of Mines in the development of 

a remote operating system (ROS) for 

control 1 i ng a thin-seam continuous miner 

(TSCM) 500 feet or more distant from the 

extraction face. Detai 1 s are provided 

on ROS subsystems i ncl udi ng the continuous 

miner, video equipment, controls and 

displays , the el ectroni c control system, 

and the operator station. 

INTRODUCTION 

This project was undertaken to determine 

the feasibility of remote, out-of-sight 

operation of a TSCM usi ng off-the-she1 f 

equipment . If remote operati on becomes 

a common, practical alternative to 

present mining methods, the industry 

should profit from significant safety 

gains, increased flexibility in selecting 

m7 ni ng strategies and expanded recovery 

of coal reserves. 

Without question, the safety of workers 

can be increased by removing them from 

the vicinity of hazards. Thus, control 1 ing a TSCM from a remote, protected 

station appears an attractive method to 

dramati cal ly increase deep mine operator 

safety because the operator is removed 

from the 25-ft zone adjoining the working 

face, widely documented as the most 

hazardous area in all mining. A stationary control station does not have to 

share the extraction area with mobile 

machinery and clearances necessary for 

tramming; it can fully utilize the 

avai 1 able space for the operator envelope 

and a surrounding protective structure. 

Remote operation a1 so removes operators 

from face area, health and congestion 

problems and increases thei r comfort. 

ROS methods are not limited to current 

mining systems or extraction 1 ocations; 

they may allow the deployment of modified, current-generati on equipment in new 

appl ications and make feasible the mining 

of reserves presently considered 

"unminable ." 

In 1979, the Bureau issued the Bendix 

Corporati on Contract No. H0308038 to 

study the feasibility of a ROS for a 

deep mining TSCM. The study showed the 

concept was attractive in both safety 

and economic terms and an initial design 

was developed [1,2]. In 1983, the Bureau 

assumed the project completely i n- house 

and fabrication of an up-dated system 

commenced. 

DESIGN OF THE ROS 

To reduce system complexity and cost, 

remote operation was considered only 

duri ng cutting and 1 oading processes; 

movement of the continuous miner from 

face-to-face was to be conducted by 

standard methods. A comprehensive 

activity analysis was performed for 

remote, within-sight continuous miner 

operati on at 2 southwestern Vi rginia 

mines. This was done to insure the ROS 

design would account for the full inclusion of tasks and individual variations 

in task performance for operators and 

their helpers, the two job classifications most affected by the planned remote 

operation. Concl usions from the study 

indicated that: 1) the concept was 

feasible from safety, techno1 ogical and 

economic viewpoi nts ; 2) an operator' s 

primary means of obtaining equipment 

control information is through vision; 

and 3) significant safety gains could be 

achieved by minimizing the presence of 

miner helpers at the face area. 

Based on the conclusions and project 

goal s, the fol 1 owi ng 1 +st of prel imi nary spec; f icat i ons was derived for 

the ROS: 1) the operator be placed in a 

ground-fall-protected station near the 

sect i on' s el ect ri cal 1 oad center, a 

1 ocati on re1 atively safe, not heavily 

traveled, and comparatively close to 

other activities and workers; 2) the 

ROS sensory, display and control subsystems i ncl ude computer support and 

a1 low efficient miner operation; and 3) 

an automatic subsystem for handling the 

water, power and signal 1 ines be designed 

for the TSCM to minimize the need for a 

80 
11 to 110 mn zoom-type lenses. Camera 

placement on the miner was designed to 

enable one camera to look toward the 

extraction face while the other can look 

in the outby direction. The operator 

can independent1 y control the field of 

view, orientation and focus of each 

camera. Cameras are moved by a hydraulic 

system that includes rotary actuators and 

cylinders. Figure 1, a preliminary 

artist's illustration of a modified 

Jeffrey 101 TSCM, shows the camera 

placement ; the actual custom-made camera 

housings are not shown - they are designed 

to minimize the TSCM' s overall height. 

Control s and Di spl ays 

In order to successful 1 y remote control 

an operation as complex as mining coal, 

the operator must be well informed on 

events occurring at the face. Initial 

requirements for the controls and displays 

were determined through an examination of 

what tasks must be conducted, what 

information the odbrator needs to conduct 

the tasks, and what sensory equipment is 

available to provide the information. 

Relative Linear Edgemeters, 

positions of potentio- baragraphs, 

auger and meters and voice 

tail-boom synthesizer 

Sounds from Mi crophone Panel - 

face mounted 

speaker 

Voi ce N .A. 

messages 

Voice 

synthesizer 

& speaker 

Electrical Pressure Analog 

and hydrau- current & meters, 

lic system voltage "Idiot 

parameters transducer Lights," and 

and thermo- voice 

coup1 es synthesizer 

As shown in Figure 2, twin 9-inch color 

video monitors placed directly in front 

of the operator provide visual information 

on face events. Auger and conveyor 

position displays are located around the 

video monitors, in or as close as possible 

to the operator's primary visual field. 

81 The remainder of the panel space is taken 
The ROSs ECS (figure 3) is built around 

two computer systems: the HOST, located 

at the operator's position, and the 

SLAVE, located on the TSCM [3]. Advantages derived from the ROS's use of 

computers include: 1) control and sensory 

data is processed and sent over only 2 

wires; 2) a wide range of sensory information is collected from the face area and 

displayed to the operator through a 

variety of user-friend1 y output devices; 

3) a voice synthesizer provides select+ ve 

information to the operator; 4) diagnostic 

functions are incorporated, simp1 ifying 

ECS maintenance and repair; and 5) operational and hardware changes are easily 

implemented. Goals strived for in the 

development of the ECS included operational flexibility, reliability, low cost. 

and use of off-the-shelf hardware. The 

HOST and SLAVE computers continuously 

communicate with each other. The HOST 

collects operator input, encodes and 

transmits it to the SLAVE. The SLAVE 

controls the TSCM based on confirmed data 

received from the HOST; it also collects 

encodes data from machine-mounted sensors 

and transmits it to the HOST. The 

HOST decodes the SLAVE data and outputs it 

to the display devices. 

signals are carried over a cable run 

alongside the existing 1 i nes . The communications 1 ink between the 

HOST and SLAVE is critical; data at a 

rate of 1200 bits/second must pass intact 

through a single twi sted.-pai r wi re contained in the signal cable or dangerous 

results, such as unintended TSCM motion, 

could occur. The need for error-free 

transmission of data between the computers, which may be 500 feet or more 

apart, is complicated by the extreme 

amount of electrical noise present in 

coal mines. This challenge is met by 

empl oyi ng short- haul modems ( Black Box 

Co. SHM-NPR) , transient suppression 

devices and special data-encryption and 

decoding software. If faulty data 4s 

received by either the HOST or SLAVE, it 

is discarded and re-transmission of the 

data is requested. Several other safety 

measures are incorporated into the system 

software to insure safe operati on i ncl uding, if conditions warrant, powering-down 

of the computers and TSCM. Entire and 

immediate shut-down of the SLAVE and TSCM 

also occurs when the large, red SQUASH 

(emergency stop) button mounted on the 

82 
control panel is activated by the operator 

or when the signal cable is severed. 

Common Subsystems 

Several subsystems are either common or 

essentially similar to the HOST and 

SLAVE including diagnostic ports, power 

suppl ies, the serial communications 

l~nk, and an acoustic feedback system. 

Both computer systems contain a diagnostic 

port normally used only during testing or 

initial set-up. If a small hand-held 

terminal device is plugged into a 

di agnostic port, system control is 

re1 i nqui shed to it . Menu-driven software 

displayed on the terminal allows an 

operator to control and monitor most of 

the ECS functions and the operation of 

the TSCM. 

As electrical transients and power 

fluctuations are common in mining and 

into1 erable in computer systems, they are 

eliminated in the HOST and SLAVE by 

special hardware. Uninterruptible power 

supplies (UPSs) provide the voltages to 

run the systems; they are directly 

powered from gel-cell batteries, which 

are constantly charged by the line 

voltage . Thi s arrangement a1 1 ows even 

complete line voltage cut-off to be 

tolerated for time periods of up to 1. 

hour. TI I Electronics Inc . EHVQ-170E-8 

switching UPSs are used; they are uncommonly efficient, directly generating 

mu1 ti pl e DC vol tages i nstead of suppl yi ng 

AC voltages. As a final precautionary 

step, the UPS inputs are connected to 

heavy-duty, i ndust-ri al-grade power 1 i ne 

transient suppression devices. 

Extraction face sound signal s are pickedup by a microphone mounted on the TSCM, 

boosted by a small amp1 ifier contained in 

the SLAVE system, transmitted through a 

twisted-wire pair contained in the signal 

cable, and presented to the operator 

through a speaker located in a display 

panel . 

The ECS software was developed using a 

high-1 eve1 programming language for the 

Intel Corp. 8085 m~croprocessor call ed 

PLIM 80. Additionally, an operating 

system called iRMXl80 (Intel Corp. and 

Micro-Managers Inc.) was used to provide 

the capability for real-time multitasking process control . 

The SLAVE Computer System 

The TSCM-mounted SLAVE system (figure 3) 

cost's approximately $8,000 (for hardware) and is essentially an intelligent 

input/ output port containing a computer. 

The SLAVE is comprised of two, customconfigured main boards: an Intel Corp. SBC 

80124 card suppl i es system i ntell igence and an Analog Devices RTI 711 card 

provides anal og-to-digital conversion. 

The boards are connected through an 

industry-standard Mu1 ti bus I card cage. 

When a valid command is received from 

the HOST, the SLAVE outputs an appropriate command sequence that activates 

relays inside the miner. At precise 

intervals, the SLAVE also samples data 

on its input ports and analog-to-digital 

converter channels, encodes the information, and transmits it to the HOST. All 

inputs and outputs are optically is01 ated 

to protect the computer system. Because 

the SLAVE is mounted on the TSCM, the 

electronic components are packaged to fit 

within a compact expl osion-proof housi ng . Although there was some concern that the 

system might be endangered by heat 

bu' 1 di ng-up in the small box, cal cul ations showed the heat generated by the 

system's 60 watts power consumption 

should be effectively dissipated to the 

outside air. 

The HOST Computer System 

The HOST system hardware costs approximately $9,000 and is contained on four, 

custom-configured main boards: an Intel 

Corp. SBC 80124 card; an Intel Corp. 

SBC 116 expansion card; and two ETI 

Micro Co.'s 8135 analog output cards. 

The boards are connected through a 

Multibus I card cage. The primary 

function of the HOST is to command the 

ECS based on input received from the 

operator. Encoded data shipped from 

the HOST, if valid, cause the SLAVE to 

exercise the TSCM. The HOST a1 so decodes 

and checks data packets from the SLAVE. 

If sensory data is received, it is 

processed and displayed on up to 48 

digital and 16 12-bit analog output 

devices incl uding "idiot 1 ights ," bargraph 

di spl ays and analog meters. P1 ug-in 

modules allow device output drive characteri stics to be easily modified. 

The HOST is a1 so equipped with a voice 

synthesi zer subsystem; it provides the 

operator with information on critical 

events during periods of peak visual 

loading. The voice synthesizer is a 

Micro Mint Sweettal ker I1 phoneme-based 

unit. Ni nety-eight project- specific 

words built into the software are combined 

as required to form complete messages. 

HOST components are packaged to maintain a 

minimum volune. Because the system is 

1 ocated i n " fresh ai r ," an expl osi on- proof 

housi ng i s not requi red . 
Operator Stat i on 

Figure 2 shows the portable control 

station designed to provide the operator 

with a comfortable, human-engineered, 

ground- fa1 1 protected worksite. The 

f 1 oor and protective canopy extend 

against the floor and roof, providing the 

operator with the largest interior space 

the seam height will allow, to a maximum 

of 42 in. Operator ingress and egress 

are provided through a sturdy horizontal 

door. The stat? on design accommodates 

operators ranging in size from 5th 

percenti 1 e female to 95th percentile 

male. The interior station dimensf ons 

are ample and the controls, displays and 

seat are adjustable through a wide range 

of comfortable operating positions . The 

stat i on col 1 afses into a compact, enclosed 

unit only 24 inches high that is towed to 

the deployment site. This helps protect 

the ECS when it is not being used. During 

towing, a two piece towbar attaches to the 

main body of the station through pin 

connectors. 

Cable Reel System 

Accident analysis showed that an automated system for keeping cable out of the 

way of the miner and haulage system could 

greatly improve system safety by minimizing the need for the miner's helper 

being at the face during mining. Therefore, a 3-section cable reel system 

was designed to handle the power cable, 

signal cable and water hose. As depicted 

in figure 1, the 1 ines are kept away from 

the equipment by a cable boom attached to 

the side of the TSCM. 

ROS Eva1 uati on 

Upon completion of the ROS, initial 

eval uation and refinement wi 11 take 

place at the Bureau's Mine Equipment 

Test Facility located at Bruceton, PA by 

attempting to cut from a block of artificial coal . Required refinements to the 

equipment, operating procedures, and 

anci 11 ary systems will be identified, 

imp1 emented , and eval uated . This phase 

will include the development of an ill umination system to be used when the 

system is deployed in the field. 

Present Status 

Evaluations to date have shown the 

Bureau' s ECS to be effecti ve in a1 1 owi ng 

the activation of the TSCM functions and 

the reception of video, audio and TSCM 

performance parameters over a signal 

cable length of 500 feet. However, the 

deep mining ROS has not been completed 

due to delays in securing a TSCM dedicated to the project and the arrival of a 

unique opportunity . An agreement has 

recently been reached with a cooperator 

who supplied a new Jeffrey Model 102HP 

TSCM to be controlled by the ROS in 

exchange for use of the control system 

with a proprietary highwall extraction 

system. The deep mining ROS system is 

presently being altered to allow its use 

for highwall extracti on. A1 though most 

of the above-descri bed developments are 

di rectly appl icabl e to the highwall 

application, required system modificati ons i ncl ude: switching the operator 

station from a thi n-seam underground 

design to a unit suited for deployment on 

a highwall bench; deleting the requi rement for an automatic cable hand1 ing 

system; re-speci fyi ng the camera deployment configuration to gain views to 

add? tional areas; and adding the requi rement for a system capable of providing 

guidance information for accurately 

positioning the TSCM. The current plan 

7s to thoroughly evaluate the ROS in 

highwall production in the near future, 

then complete its deployment and assessment as a deep mining system at a future 

date. 

CONCLUSIONS 

The remote operation of continuous 

mining machines 500 or more feet distant 

from the extraction face appears as an 

attractive means of significantly 

increasing operator safety, a1 lowing 

increased flexibility in selecting 

mini ng strategies and expand? ng the 

recovery of coal reserves. The Bureau's 

current ROS developments appear encouraging, but are yet unproven. Potential 

control problems include that the video 

information provided the operator will 

not supply three dimensi onal perception, 

and proven coal to roof and floor interface sensors are not available that 

would increase the probability of the 

TSCM remaining in the coal seam. However, 

confidence remains high that future system 

refinements combined with sensor advancements wi 11 a1 low the developed ROS to mine 

coal effectively and serve to promote 

widespread deployment of thi s techno1 ogy 

throughout the mining industry. 

REFERENCES 

1. Hartley, C. and C. Fazio, "A Study 

To Determine The Feasibility of Providing 

Adequate Human-Engineered Operator' s Cabs 

In Thin Seams Through The Use Of A 

Remotely Positioned Operator," Bureau of 

Mines Contract H0308038 Phase 1 Report, 

March 1981. 
2. Hartley, C., R, Cooksedy and C. Fazio, 

"A Study To Determine The Feasibility of 

Providing Adequate Human-Engineered 

Operator's Cabs In Thin Seams Through The 

Use Of A Remotely Positioned Operator," 

Bureau of Mines Contract H0308038 Phase 2 

Report, March 1982. 

3. Schiffbauer, W. H. An Intelligent 

Remotely Operated Control 1 er for Mi ni ng 

Machines. Proc . The Third Conference 

on the Use of Computers in the Coal 

Industry, Morgantown, WV, Jul . 27-29, 

1986 .