Table 1.—Specification for AMP recorders
Part number 1005083-1

Sensor type..... 3-axes piezoelectric accelerometer

Dynamic range... .. #2 to +200 g in each axis

Cross axis .. 5% typical

Digitization. . 10 bits

Sampling frequency... .. User programmable from once every 1 to 50 msec
Lower frequency limit . 1.5 Hz

Upper frequency limit...... .. 90 Hz

Trigger threshold... User programmable 2 to 50 g

.. Better than 4% full-scale over temperature

Accuracy of acceleration .....
.. Better than 5% full-scale over temperature

Accuracy of peak...
.. 1 sample

Pretrigger....

CONCLUSIONS

A data collection system that ties acceleration and GPS
location data has been successfully demonstrated at a
cooperating mine. A variety of applications are possible.
Utilizing sophisticated hardware and software allows for
monitoring very low level accelerations and results in more
functionality. Using plotting software, the person reviewing
the data produced can “see” the acceleration of the truck
much like an infrared camera can display the thermal
signature of a moving object. Utilizing inexpensive
hardware and software, severe jolts can be effectively
monitored.

4 Copyright © 1999 by SME


SME Annual Meeting
March 1-3, 1999, Denver, Colorado

Preprint 99-118

TYING ACCELERATION AND GPS LOCATION INFORMATION TOGETHER TO CREATE
A MINE MANAGEMENT TOOL

RE. Miller

NIOSH

Spokane, WA

P. Boman
J. Walden
Phelps Dodge Morenci, Inc.
Morenci, AZ

S. Rhoades
Modular Mining System, Inc.
Tucson, AZ

R. Gibbs
Phelps Dodge Tyrone, Inc.
Tyrone, NM

ABSTRACT
Accelerometers and pressure transducers mounted in
suspension components can be used to monitor the tide of
haulage trucks. Presently, it is difficult to tell what caused a
jolt to the truck using either pressure or acceleration data
alone. When information from a Global Positioning System is
recorded at the same time as shock pressures or acceleration
data, then the exact location of an event can be determined.
Mine management can then determine what caused the jolt to
the truck.

INTRODUCTION

This research is part of a National Institute for Occupational
Safety and Health (NIOSH) project called “Engineering
Controls for Reduction of Jolting/Jarring Injuries in Surface
Mines.” Phelps Dodge Morenci, Inc. (PDMI), and NIOSH
are working together to investigate how the work environment
of haulage truck drivers can be improved. The Mine Safety
and Health Administration (MSHA) notes that 60 pct of the
back injuries were to haulage truck drivers; in metal/nonmetal
surface mining between 1986 and 1995. It was suggested by
mine personnel that combining acceleration data with
information obtained from a Global Positioning System (GPS)
could generate results with a variety of uses. Therefore,
Spokane Research Laboratory (SRL) researchers began

investigating how to tie acceleration and GPS data together.
It was originally thought that this tool would be used
primarily for road and truck maintenance, but as research
progressed, it became apparent that it would also be useful in
providing feedback about equipment operations and
identifying unusual causes of jolting.

EXPERIMENTAL APPROACH

Readily available components that function well by
themselves were linked for the purpose of proof of concept.
Utilizing a Modular Mining Systems, Incorporated (MMS)
product called Vital Signs, SRL researchers took an AMP
acceleration recorder and hardwired it to MMS Dispatch
equipment already installed on the truck. AMP is one of
several manufacturers of acceleration recorders frequently
used to monitor freight during shipping. MMS Dispatch is
used for production accounting and truck dispatching and
utilizes GPS tracking. Through Vital Signs, an analog or
digital alarm signal can be recorded. Steve Rhoades, MMS,
wrote unique code that links the Vitals Signs data and GPS
location and stores these data in an ASCII log file. SRI
researchers and Jeff Walden of PDMI worked together to
install the equipment in a Caterpillar 793 haulage truck. The
result was a successful, working prototype.

Copyright © 1999 by SME



Figures 1 and 2 show the instrument installation in the truck.

Figure 1. — View of “buddy seat” where
acceleration recorder was installed.

r hae RE:
Figure 2.—AMP acceleration recorder in upper
right corner

DISCUSSION
From 8:30 p.m. September 14th until 6:50 a.m. September
15th, 899 jolts above a threshold of 2 g were measured on
the test truck, As figure 3 illustrates, some sections of the

Figure 3. — GPS data points for acceleration events
(Garth Frankel, Spokane Research Laboratory)

haulage road produced most of the events, while many
others produced no jolts at all. As figure 4 illustrates, 2 g is
a relatively low threshold for jolts. Because the threshold is
low, when plotting the data, the movements of the truck in
some sections of haulage road can be seen. Watching the
acceleration signature of the truck is comparable to watching
the thermal signature of a moving object with an infrared
camera.

The data have many uses. For example, they can be used
to—

© Determine if, how often, and of what intensity are severe
jolts that could pose a health concern.

¢ Monitor driving style and skill.

Gather baseline data on truck performance to compare
with future truck performance,

© Monitor road conditions.

As with any tool, proper use is the key to getting the most
benefit. Some applications would require a very low
threshold setting and would require large data storage and/or
fast radio systems. To determine the location of potholes, for
example, an event would have to be picked and then all
other events within a given radius of that selected event
would need to be located. If a significant number of events
occurred around a specific location, then it would be safe to
assume that a pothole exists in the haulage road at that
location. The emphasis at any specific mine would dictate
threshold levels and sampling rates. A simple use of the tool
is to set the acceleration threshold at some high level,
beyond what normal operation should produce. Therefore,

Copyright © 1999 by SME


produced, it is rare and more attention is paid to finding out
what caused it. Examples of root causes for high acceleration
events include—

« Extreme speed for road conditions.
© Truck striking a berm or other object.
© Shovel striking the side of truck bed

A pertinent question concerns how this data would affect
production. Would it cause drivers to slow down or act
tentatively? The key here is how the data is managed. Future
research will be focused on determining positive and negative
effects.

Costs per truck to install this system are not yet available and
depend on how many functions would be built into it. As
noted earlier, the possibilities for powerful diagnostic software
are numerous. On the hardware side, the AMP shock recorder
operates on batteries and has built in data storage. The next
generation prototype would be simplified and tap into the
truck's system for electricity. It would be an analog triaxial
accelerometer connected to a digital component. The digital
component would monitor all three axis and send out an alarm
signal when a preset threshold is exceeded.

The present specifications of the AMP recorder are given in
table 1.

o
Ww 200 VY, TT T
Oo
I 100;-- a
Wi 80- N 4

60+ \ 4
LL
O 40 IN UY Acceleration _|
3 N moderate injury Limits upon which
= “77 S SSSI current ejection =
x seats are designed
oc Area of voluntary
wi 0 human exposures 7
1 8 Yes undebilitated) 4
W 6h (7 7 injured, undebittated) 4
O 4b YY, |
< Yy
s “A
ao 2r 5
ie)
5 1 ! [a ee ee ee oe oe
5 0.001 0.002 0.004 0.01 0.02. 0,04 01 #02 0.40.6 1.0

0.006 0.06

DURATION OF UNIFORM ACCELERATION, sec

Figure 4. — Effect of uniform acceleration on humans (M. Eiband, NASA Memo 5-10-95E).

Copyright © 1999 by SME