A GUIDANCE SENSOR FOR CONTINUOUS MINE HAULAGE

JOHN J. SAMMARCO

U.S. Department of Energy

Pittsburgh Research Center

P.O. Box 18070

Pittsburgh, PA 15236 USA

Abstract—The U.S. Bureau of Labor Statistics reports that the

mining industry has the highest average annual fatality rate (31.9

per 100,000 workers) among all major American industry. To

address this, a major research program to reduce hazard exposure

of miners with computer-assisted mining equipment was initiated by

the U.S. Bureau of Mines. One application involves the manual 1

process of extracting and hauling coal where operators, in the tight

confines of a mine, can be struck or caught by mobile machinery.

The approach to remedy this problem uses a guidance system on the

haulage equipment so that it follows the machine that extracts coal.

This, in essence, involves sensor-based docking of the machines.

Sensors that can survive the hostile mine environment of dust,

methane gas, and water, play the key role. Computer analysis of the

mining machine's movements and empirical machine characterizations were conducted to establish operating requirements and

spatial limitations to ensure proper loading of coal into the haulage

equipment. These data served in the selection of a sensing system.

Various technologies such as scanning laser systems and ultrasonic

sensors have frequently been used in other applications but were

found unacceptable. However, a near infrared (IR) sensor employing active targets met the requirements. The sensor has a nominal

75E conical field-of-view and a range from 0.1 to 18.0 m. For the

single target mode, nominal range accuracy was 4.3% at a distance

of 3.56 m. Correction algorithms were generated reducing the error

to 0.6%. Airborne dust testing showed less than 0.8% accuracy

(worst case) degradation at levels exceeding (by a factor of 7.5)

concentrations permitted by Federal law. The sensor can track

multiple active targets providing five degrees-of-freedom (DOF)

measurements. Using four targets, the nominal range accuracy was

0.4% without correction algorithms. A guidance system for the III. CURRENT OPERATING SCENARIO

haulage system to follow the mining machine does not exist commercially. Such a system can reduce fatalities and injuries by current

haulage mining equipment, and is a viable alternative to current

haulage control.

I. INTRODUCTION

Coal generation plants provide about 60% of our nation's electricity thus making the mining industry a vital part of our national

interests. The mining of this coal is quite dangerous for workers.

The mining industry has the highest annual average fatality rate of

31.9 per 100,000 workers [1]. Congress mandated the U.S.

Bureau of Mines (USBM) to "conduct necessary research and 1

development to improve working conditions and practices . . . to

prevent accidents."

To address this situation, the USBM initiated a program to

develop the enabling technology for a reduced exposure mining

system (REMS) [2]. The objectives are to reduce hazard exposure and improve the safety of miners working in the most

hazardous areas of the mine. REMS uses computer-assisted

machine operation that places operators in the safety of a control

center.

II. BACKGROUND

The initial application of REMS involves underground coal

mining, specifically room-and-pillar type methods. Currently, we

are integrating the extraction and haulage processes so that the

coal can be properly loaded from the continuous mining machine

into the continuous haulage machine. This task requires the

haulage machine to maintain a critical position and orientation as

it follows the mining machine.

Positioning mobile equipment is not unique to mining. It is a

generalized problem [3]. Research conducted by Sandia Labs

concerned sensor-based docking of large payloads [4]. Sensorbased programmable vehicles are used for the transport of

hazardous materials or for operation in hazardous environments.

Other applications involve military ground vehicle conveying [5]

where sensor-based vehicles follow a lead vehicle.

Coal mining utilizes specialized methods and machines. A

common method is known as room-and-pillar mining, in which

tunnels are cut according to a predefined manner such as a

rectangular grid or a "chevron" pattern. Fig. 1 depicts a small

section of this pattern and the equipment used for mining. The

main tunnels are "main entries" and the side tunnels are "crosscuts". Main entries are from 5.5 m to 6.0 m wide. Crosscuts are

typically 3.3 m. The main entry distances between crosscuts are

typically 6.0 m to 12.2 m. 

The major stages of operation are initial alignment, advancing the

face, turning crosscuts, and backing out of an entry. 

A. Initial Alignment: The haulage operator manually positions

and controls the haulage machine behind the tail end of the mining

This project originated under the U.S. Bureau of Mines Pittsburgh Research machine, using a radio remote control pendant. The objective is

to have the tail end of the conveyor placed directly overtop of the

1

Center. The U.S. Congress directed, in Public Law 104-99, 110 Stat. 26

(Jan. 26, 1996), that the health and safety functions of the Pittsburgh Research

Center be transferred to the U.S. Department of Energy.
Fig. 1. Room and pillar mining in a cheveron pattern.

hopper car of the continuous haulage machine to ensure that coal

will fall into it when the mining process begins. The second part of this hybrid control uses computers and sensors

B. Advancement: The mining machine operator controls the control of the mining machine. A sensing system is needed to

mining machine to cut coal and move the machine forward to cut measure the relative X, Y, and Z position and Yaw of the hopper

the main entries and crosscuts of the mine, using a radio remote car with respect to the continuous miner. REMS is implemented

control pendant. In the development of the main entries, the from the control room for this phase.

mining machine takes two cuts to obtain the desired width.

Crosscuts are developed after the main entries. Usually the V. REQUIREMENTS ANALYSIS

mining machine makes one pass (cut) to advance crosscuts. If a

wider entry is required, two passes will be taken. During Computer-assisted mobile mining machines have many of the

advancement stages, the haulage operator’s job is to maintain the same requirements as computerized mobile vehicles in other

position of the hopper car under the conveyor. industries. Foremost is the need to determine the machine's

C. Turning a Crosscut: The mining machine begins in the main example, the application environment can pose many limitations

entryway. To develop the 60E crosscut, the machine must be and requirements on the sensing systems. Underground mining is

turned while cutting. This is difficult to do because a considerable one such application. It is a dynamic environment of explosive

amount of positioning and maneuvering of a large mining machine atmospheres and changing physical configurations as new areas

in a tightly confined space is needed. A typical footprint of the are mined. Sensors must not only provide accurate measurement

mining machine is 3.3 m by 6.0 m. Also, movement is restricted data, but they must operate safely and reliably in the mine.

since the haulage machine follows closely behind.

D. Back out: The mining machines must be backed out to begin

the next set of cuts. The primary objective is to ensure that the 1) Dust: Airborne dust concentrations vary in relation to the

machines do not collide as they back out. The operators must particular mining task. Federal law, mandated by the Mine Safety

work together to prevent this from happening. and Health Administration, sets a maximum level of 2 mg/m for

The haulage system used for our research is a Joy 3FCT-4

machine. It is a flexible belt system that winds its way through 2) Moisture: The sensor will be subjected to direct water 2

the mine under control of an operator. The tail end discharges contact from splashing or dripping from the roof. Relative

coal onto the section or main belt while the receiving end, called humidity can exceed 95%.

the hopper, is guided by the operator to follow the rear of the

continuous miner. Operators are in the dangerous area between 3) Explosive Atmosphere: Methane gas is often present in

the machines where the roof could fall and where they can be mines along with airborne coal dust. This mixture can present an

struck or pinned by moving machinery. This situation is made explosive atmosphere depending on the fuel-to-air ratio and is

more dangerous since visibility is limited by dust, obstructions,

and low levels of light. Significant levels of noise, especially

during the cutting of coal, can impair hearing and communication

between the operators. 

IV. REMS OPERATING SCENARIO

The proposed operating scenario employs a hybrid approach

combining manual and computer-assisted control. Initial machine

alignment (stage 1) is done by manual control since much

maneuvering is needed and is most effectively done by humans.

Radio remote pendants for the haulage and mining machines are

used for this stage. The initial alignment stage is unchanged from

the manual method. Manual alignment also enables visual

inspection of the machines before operation from the control room

begins. The exposures to hazards are less at this stage since the

machine is not cutting coal; thus, dust and noise are minimal.

for proper positioning of the haulage system and to assist in

position and orientations. This is a challenging problem. For

A. Environmental Requirements:

3

human exposure. 

ignitible by electrical and thermal energy. Therefore, the sensor

must be of intrinsically safe design or made permissible. Use of product names is for identification only and does not imply endorsement 2

by the U.S. Department of Energy, Pittsburgh Research Center.
B. Operational Requirements: Computer analysis of the mining 2) Back out: The most critical item here is to ensure that the

machine's movements and empirical machine characterizations machine separation distance does not damage the tethered power

established operating requirements and spatial constraints. cable. The maximum separation is 3.66 m. Exceeding this is

Each operational stage needs X, Y, and Yaw data. Additionally, machine reverses at 19.5 m/min versus 16.2 m/min for the mining

Z data are of use for special situations. For example, it is ex- machine. When backing out of a 12.2-m section, three to four

pected the machines will exceed the loading zone of fig. 2 to stops of the haulage is needed to avoid excessive separation.

handle certain exceptions during the mining process. Z data

become useful to detect when the conveyor height is below the top 3) Turning a Crosscut: Cutting the 60E crosscut is the most

of the hopper car. One can then avoid ramming the conveyor into difficult phase of operation to coordinate between the machines.

the hopper car when returning the machines to the loading zone. Analysis of such a cut shows a maximum angle between the

For example, uneven floors could cause this situation. Under machines of 41E. Secondly, the maximum length of cable

ideal conditions, the vertical clearance is only 22.9 cm. The Z between the two machines is 3.66 m, thus giving a second

data are not needed for the back out since coal is not loaded. constraint for turning the crosscut. This is depicted in fig. 3.

For each stage, the general operational needs are that (1) the VI. POTENTIAL SYSTEMS

relative positions of the machines are within the proper zone,

(2) the tethered cable between the machines is not over extended, Everett [6] and Borenstein [3] present overviews of various

(3) the sensor provides position data for all stages. sensors for positioning mobile vehicles. These include gyro1) Advancement: Fig. 2 depicts the loading zone for the two systems. For example, an active laser ring gyroscope-based

vehicles. Empirically, a 15.2 cm trajectory of coal from the end system has been produced by Honeywell Military Avionics. It is

of the conveyor exists and the conveyor swing is 86E. The called the Modular Azimuth and Positioning System (MAPS);

conveyor is positioned fully up. This affords a 22.9 cm clearance prior research [7] investigated it for mining applications.

between the top of the hopper car and the bottom of the conveyor. Additional development and refinement of the system [8] has

With these parameters (given X, Z, and Yaw = 0), computer shown this to be a viable method of determining machine position;

analysis sets a maximum separation distance of 121.9 cm. The however, the cost is prohibitive for this application.

minimum separation of 15.2 cm provides a "cushion" space.

Fig. 2. Loading zone for the continuous mining and haulage machines. Fig. 3. Cross cut paramaters.

possible since the machines move at different rates. The haulage

scopes, RF position location systems, and ultrasonic and optical
Military applications have also driven the need for navigation varied considerably due to the uneven mine floor. Another

technology employing radio frequency (RF) navigation for concern pertains to the physical robustness of the scanning mirror

ground-based or satellite-based systems. Ground-based RF mechanism. The sensor in the haulage application would mount

systems exist from Harris and Motorola as described by on either the haulage machine or the mining machine. Both

Everett [6] and Borenstein [3]. Complete system cost can range machines could encounter significant shock and vibration that may

from $75,000 to $100,000. Harris Technology also offers a become problematic for a scanning sensor.

ground-based RF positioning system; however, the resolution

range, 0.1 to 0.3 m, is unacceptable for the mining application. "DynaSight", a near-IR sensor, was identified as a potential

Obviously, satellite-based systems will not work for underground system. A review of the manufacturer’s specifications and

mining applications although they may have merit for surface subsequent discussions led to additional investigation. 

mining.

Ultrasonic sensors, ubiquitous in industrial applications, were

investigated by the USBM for navigation of underground mobile The DynaSight sensor is a commercial electro-optic sensor used

mine equipment [9]. Results were favorable for distance mea- to measure X, Y, and Z of a target. It is a low-cost system, costing

surements to mine features such as ribs, corners, and intersections. about $2.2 K. DynaSight does noncontacting measurements to an

The application for underground haulage guidance differs in the active or passive target. Optionally, the sensor can track multiple

characteristics of the target, which is the back bumper of the active targets with an Active Target Adapter (ATA).

continuous miner. It is a smooth piece of metal, 29.2 cm high and

195.6 cm long. The bottom of this bumper is 38.1 cm high from The sensor uses eye-safe IR in the wavelength of 890 nm and has

ground level. From crosscut analysis, two parameters, incident a nominal 75E conical field-of-view. Optionally, the field of view

angle and range, become very important in selection of an can be factory set for 50E. Measurements are referenced to a

ultrasonic transducer. The maximum incidence angle is 41E; fiducial mark on the sensor’s front panel. The coordinate system

therefore, the beam angle of the transducer must exceed this value is right-handed as referenced facing the sensor. This varies from

to receive the echo from the bumper. Let the beam angle be 45E the mine coordinate system where Z and Y are interchanged.

and target distance equal 3.66 m. With these parameters, the spot

diameter (D) of the ultrasonic beam is calculated as When using passive targets, the near-IR light source is emitted

D = 2R.tan(0.5 %)

where R = target range

% = beam angle 

Spot diameter is calculated as 303.02 cm. One quickly realizes

the large spot diameter overshadows the 29.21 cm high bumper

thus causing target recognition problems. The sensor could

possibly read reflections from the walls, floor, ceiling, and

conveyor of the continuous miner. 

A commercial device for docking is available by Cybermotion. It

consists of a vehicle-docking computer and a vehicle-docking

head using ultrasonic transducers and infrared (IR) transponders.

The ultrasonic beam width of 15E is much less than the 41E

needed during the crosscut. Other position systems are posted in

frequently asked questions (FAQ) by Dowling [10].

Part four of the FAQ concerns sensors for measuring three or six

degrees of freedom. The systems include electromagnetics and

scanning optical systems. Electromagnetic devices were found

unacceptable when Sammarco [11] documented the difficulties

with electromagnetic devices for a mining machine.

Prior work by Anderson [12] investigated a scanning laser system

with passive targets for position measurement of a mining

machine. Favorable accuracy results were obtained; however,

target loss was an initial problem since the pitch of the mining

VII. CANDIDATE SYSTEM

from two arrays separated by a known distance at the front of the

sensor. In this configuration, the sensor operates in a

retroreflective mode. The range is proportional to the target size

where the 75 mm target enables measurements to 6 m. With

passive targets, the angular response is about ±45E for the passive

targets. Here, target reflectivity increases as the entrance angle

increases from 0E to about 40E. Reflectance drops sharply once

the angle exceeds 45E; therefore, range and accuracy degrades.

When using an active target, the sensor is set to the "laser mode".

Here, IR light is emitted from an active target and received by the

sensor. An active target triples the range and doubles the target

entrance angles. The sensor can rotate ±35E(given a 70E field-ofview (FOV)) about vertical axis through the sensor’s fiducial

mark; the target orientation can vary ±45E for passive targets and

±90Efor active targets. Hence, the objects on which the sensor

and targets are mounted can undergo a substantial range of

orientations relative to each other. This is important to understand

since during the crosscut situation depicted in fig. 3, the sensor

and the target will be at varying angles of rotation.

The "standard" configuration of the sensor is set for a single active

target. With the optional ATA and a second target, calculation of

Yaw is possible. This configuration also enables redundancy

which is desirable since some targets could be "lost" to failure or

be out of the FOV. As the number of targets increases, the update

rate decreases. With four targets, the update rate is 16 Hz for each

target or a 4-Hz total update rate.
Since the mining machines move slowly, this update rate is Testing used 22-mm and 75-mm target sizes at distances of

acceptable. The maximum machine forward speed was measured 0.31 m, 2.44 m, and 3.65 m. Measurements were taken with

at 17.53 m/min when moving in free space on a concrete floor. targets perpendicular (a target angle of 0E) to the fiduciary mark

Thus the maximum machine movement between updates is less of the sensor’s optical head. Next, the target was rotated to 45E

than 7.62 cm. The most critical period is during the cutting of the and the tests were repeated. This is of interest since the requirecoal where the mining machine moves less than 5 cm/s. Maxi- ments analysis showed the targets could be at 41E during crossmum movement between updates is less than 1.3 cm for this cuts. Target reflectance begins to significantly reduce at 45E, so

period. testing was needed to evaluate operation at this angle.

A. Sensor Diagnostics: Diagnostic data, for passive or active The next stage of testing involved the repetition of tests at target

targets, are given in two forms. First is a visual indication, using angles of 0E and 45E while using the optical window needed for

a single LED, and second is a digital status word embedded within the XP enclosure. The window was a 1.26-cm thick fire-polished

the sensor’s output. borosilicate glass with ground and chamfered edges. The intent

Diagnostics are given for four conditions. They are search, coast, window. 

caution, and track. During the search mode, the LED is red. The

second mode, called coast, is when the sensor has locked on Finally, tests involved false target rejection and target obstruc-

(found) a target, but has lost it and is attempting to reacquire it. tions. Multiple sources of false targets existed in this mining

During coast the LED is red. The third mode is caution. For this application; however, two were of prime concern. They were

mode the LED alternates between red and green. During caution, incandescent lights found on miners caps and mounted at the rear

conditions are marginal and target loss is imminent. This caution of the mining machine, and retroreflective tape found on machines

status can be extremely helpful for the mining application. If loss and miners’ caps. Target obstructions could occur as roof

of a target is imminent, the controller of the mining machine can material falls or if coal is improperly discharged from the contake alternative action or invoke an orderly stop. The last mode veyor into the haulage equipment. Of interest was if and how

is called track where the signal-to-noise ratio of sensor data is quickly the sensor finds and locks on the actual target rather than

acceptable and target loss is not imminent. During track mode, the false targets. Operators could also step within the sensor's

the LED is green. FOV, causing a target obstruction. False targets and obstructions

VIII. TEST SETUP room while the machines are controlled; however, it is unrealistic

Testing of the sensor was conducted in the controlled environ- design. 

ments of a lab and in a dust gallery. Lab tests investigated the

feasibility of the technology for the mining application. The main B. Active target tests: Testing of the active targets followed the

test areas concerned accuracy and adaptability for mining. same format as for passive targets. The main changes were with

Lab tests were designed to address the following questions: from 0.3 m to 0.6 m because the sensor did not provide reliable

Should passive or active targets be used and what were the measurements for distances less than 0.6 m. The maximum

associated accuracies? Next, assuming the sensor's accuracy was distance was increased to 4.4 m to accommodate a distance of

sufficient, could the sensor be approvable for operation in an 1.2 m from the sensor’s mounting location to the front bumper of

explosive mine environment of dust and methane? The sensor the haulage machine. In other words, at a machine separation of

could be approvable if mounted in an explosion-proof (XP) 3.7 m, the target reference point is 4.9 m from the sensor’s

enclosure fitted with an optical window. However, would the fiduciary mark (assuming X, Z, and Yaw = 0).

optical window impede proper sensor operation and degrade

accuracy? The first group of tests used a single active target. The next group

Once feasibility was confirmed, dust tests were conducted. Of Spacing was 30.5 cm between each target; thus, the distance from

primary interest was the effect of airborne dust on accuracy and target 1 to target 4 is 91.4 cm. Target measurements are refersystem robustness. Dust testing was of much interest since enced to the center of the array, located 45.7 cm from the outerairborne dust is always present in mining and can be especially most targets.

problematic for an optical sensor.

A. Passive target tests: The basic equipment setup consisted of within a dust gallery. The sensor was mounted within a dust-tight

the sensor connected to a PC via RS-232c. The PC ran software enclosure fitted with the borosilicate lens. A dust mixture was

written in C to acquire sensor data and to display the output in real introduced into the chamber at dust levels starting at 2 mg/m .

time for monitoring. Dust levels concluded at 15 mg/m , the maximum obtainable by

was to determine accuracy and range degradation due to the

caused by miners is unlikely since they are to be in the control

to assume human behavior will always be consistent with the

the measurement ranges. The minimum distance was changed

used the ATA with four active targets arranged in a linear array.

C. Dust tests: Lab tests for a single active target were repeated

3

3
Fig. 5. Compensated errors for a single target oriented at 45E.

the test apparatus. For each level of dust, the targets were of the errors, a second order polynomial was generated for error

oriented at 0E, 20E, and 40E relative to the fiduciary mark. These compensation of Y data for target rotations of 0E, 20E, and 45E.

orientations were set for each target distance of 0.6 m, 2.5 m, The equation is

3.6 m, and 4.9 m. 

IX. TEST RESULTS

A. Passive targets: The initial test results, using a 22-mm target,

are shown in fig. 4. The graph depicts a collection of four test Applying this compensation reduced errors significantly as seen

conditions of "Y" measurements. Of interest was the sensor's by fig. 5. The worst case error was reduced from 4.3% at a

accuracy at varying distances when the target angle was 0E and distance of 3.6 m to 0.6%. Fig. 5 depicts one set of data where the

45E. These conditions were repeated using the optical window. target angle is 45E without a window for the sensor. An analysis

In general, errors increased proportionally to distance with the advancing the face. This is also when accuracy is most crucial

worst case error of 10 cm at a distance of 3.6 m where the target since this is when coal is loaded into the hopper. The analysis

was at 0Eand without the window. It was expected that as the gave a machine separation of 2.5 m to 3.7 m for this. The worst

target was rotated, errors would increase. Also, errors would case compensated error was 1.4 cm while the worst uncompenincrease when the optical window was used. In some cases, such sated error was 15.2 cm for this range.

as at 0.6 m, this was true. Overall, no generalized pattern,

dependent on the lens or target rotation, was evident through the C. Dust tests: Dust test results showed a maximum error increase

range of measurements. of less than 0.8% with respect to readings at 0 mg/m of dust.

At this point in testing, attention focused on false target recognition. False target sources such as a miner's caplamp were

introduced into the sensor’s FOV while the sensor was "locked

on" the actual passive target. At distances of 0.6 m, 2.5 m, and

3.6 m, the sensor did not detect the caplamp. Even if an obstacle

obstructed the target, the sensor would, within 0.3 sec, "lock" back

onto the passive target and not the caplamp. Tests with reflective

tape on a miner’s cap showed that when the target was obstructed,

the sensor would "lock" on the false target of reflective tape.

Thus, the passive target was deemed unacceptable.

B. Single active target results: Tests show that target rotation has

a minor effect on the accuracies. Again, error was directly

proportional to the measurement distance. Given the consistency

 Fig. 4. Passive target results with and without a borosilicate glass window.

Compensation factor = .0003X - .9933X + .7796 2

where the goodness of fit measure R = .996. 2

of machine operations showed that most of the time is spent

3

This is quite noteworthy since this error was at concentrations of

dust more than five times the acceptable level. At the maximim

acceptable dust concentration of 2 mg/m , the maximim error was 3

0.41%. Dust test results showed very good accuracy at all dust

levels; hence, airborne dust is not expected to be a problem for the

sensor.

D. Multi-target tests: Next lab tests were conducted using the

ATA and four targets. The error data are given in table 1. Two

active targets, separated 121.9 m, were used. The measured data

values for X and Y were constant where X = 0.5 cm and Y =

1.2 cm. The errors are from raw data. Worst cases and best cases

are identified. Average errors at the minimum and maximum

loading ranges are shown in table 2. 
TABLE I

ERROR DATA USING THE MULTI-TARGET ADAPTER

Y Yaw Yaw X Z Y

 measured, m measured, E error, E error, cm error, cm error, cm

1.22 0 -1.7 -2.8 0.3 -10.01

1.22 20 6.9 4.8 -0.7 -5.8 1 1

1.22 45 NA NA NA NA

2.44 0 -1.6 0.08 0.5 0.02

2.44 20 4.8 -2.7 0.1 0.4

2.44 45 -1.2 -4.6 0.1 3.7 2

3.65 0 -1.6 -1.3 2.4 0.81

3.65 20 4.8 -3.7 0.8 0.22

3.65 45 -1.2 3.8 0.8 2.0

4.87 0 -1.7 0.8 -1.2 0.02

4.87 20 -1.9 -2.6 0.8 1.0

4.87 45 -3.5 -4.2 0.8 1.6

 NA NOT APPLICABLE

WORST CASE 1

BEST CASE 2

TABLE II

AVERAGE ERRORS AT THE MINIMUM AND MAXIMUM LOADING RANGE OF TABLE 1

Y Yaw X Z Y

measured, m error, E error, cm error, cm error, cm

Average Std. Dev. Average Std. Dev. Average Std. Dev. Average Std. Dev.

2.44 0.67 2.93 -2.41 1.92 0.03 0.04 1.53 1.53

4.87 -2.37 0.81 -2.27 1.73 0 0 0.47 1.47

Significant accuracy improvements are evident in comparisons of control system. The SBC also implements target redundancy and

the uncompensated single and multi-target error data of fig. 6. As algorithms for tracking multiple targets.

a reference point, Y errors at 3.65 cm (expressed as a percentage

of reading) were nominally 0.6% using correction algorithms for The mining machine control system was developed in the REMS

single target data while multi-target error was 0.4% without using program by the USBM. The controller is used for the crosscut,

correction algorithms. advancement, and back out of the mining machine. It also is used

X. SENSOR INTEGRATION system manipulates machine position through forward and

Fig. 7 is the block diagram for integrating the sensor into the elevation and swing of the conveyor. The scope of control for this

haulage system and mining machine. The sensor sends, via system includes the haulage machine. Thus, the control system

RS-233, raw sensor data to a PC/104 single-board computer can send control commands to the haulage system to manipulate

(SBC). The SBC processes raw target data and sends, X, Y, Z, position and orientation.

Yaw, and diagnostic data, via RS-485, to the mining machine

for coordinated control with the haulage machine. The control

reverse translations, pivots, and turns. It also can control the
Fig. 6. Single and multiple target comparisons.

Fig. 7. System block diagram.

XI. FUTURE WORK ultrasonic ranging sensors in an underground mine.

The DynaSight sensor holds much potential for applications in [10] K. Dowling, Robotics: comp. robotics frequently asked

mining as evident from the testing and analysis described. Next, questions. 1995. Available as a hypertext document,

long-term field testing in actual mining conditions will be http://www.frc.ri.cmu.edu/robotics-faq.

conducted. Of interest is sensor operation during cutting periods [11] J. J. Sammarco, Mining machine orientation control based

when machine vibration is maximum, and secondly, how well the on inertial, gravitational, and magnetic sensors. BuMines

sensor operates as dust accumulates on the optical lens and active RI 9326, 1990.

targets. Also, packaging modifications are desirable such as [12] D. L. Anderson, "Position and heading determination of a

repackaging the sensor's optical head to improve accuracy and continuous mining machine using an angular positioneliminating the active target tether to simplify the system. sensing system. BuMines IC 9222, 1989.

XII. CONCLUSIONS

The implementation of REMS for integrating the extraction and

haulage process could reduce the potential of miners being struck

or caught by moving machinery. This requires a system to

determine the haulage machine's X-Y position and Yaw. The

DynaSight sensor, with an active target, is the best candidate

based on accuracy, excellent operation in airborne dust, false

target rejection, and cost. In comparison to a single active target,

the multi-target option for the sensor is the most desirable for

mining applications since this mode has target redundancy,

improved accuracies, and reduced hardware.

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