20 AUGUST 2000 ■ MINING ENGINEERING

Accelerometers and pressure transducers, mounted

in suspension components, can be used to monitor

the ride 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

(GPS) is recorded at the same time as shock pressures or

acceleration data, the exact location of an event can be

determined. Mine management can then determine what

caused the jolt to the truck.

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.” NIOSH is investigating how the work

environment of haulage truck drivers can be improved.

The US Mine Safety and Health Administration

(MSHA) notes that, between 1986 and 1995, 60% of the

back injuries were to haulage truck drivers in metal/nonmetal surface mining. Personnel from Phelps Dodge

suggested that combining acceleration data with information obtained from a GPS could generate results with

a variety of uses.

Therefore, researchers at the Spokane Research

Laboratory (SRL) 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. However, as research progressed, it became apparent that it would also be useful in providing

Acceleration and GPS data

monitor truck-haulage jolts

R.E. Miller, P. Boman, J. Wa

S. Rhoades and R. Gibb

R.E. Miller is a principal investigator with 

Institute for Occupational Safety and Hea

Research Laboratory, 315 E. Montgomery Av

WA 99207. P. Boman is industrial h

Phelps Dodge Miami, PO Box 4444, Claypo

J. Walden is an electrical engineering tec

Phelps Dodge Morenci, Morenci, A

Rhoades is a principal support engineer w

Mining Systems, 3289 E. Hemisphere Loo

85706. R. Gibbs, member SME, is senior 

ning engineer, with Phelps Dodge Tyrone, 

Tyron

FIG. 1.

View of “buddy seat” where an acceleration recorder was installed.

feedback about equipment operations and ide

unusual causes of jolting.

Experimental approach

Available components that function well b

selves were linked for the purpose of proof of c

Using a Modular Mining Systems (MMS) produ

Vital Signs, SRL researchers took an Aero-Marin

ucts (AMP) acceleration recorder and hardwir

MMS Dispatch equipment already installed on 

AMP is one of several manufacturers of accelera

corders frequently used to monitor freight duri

ping. MMS Dispatch is used for production acc

and truck dispatching and uses GPS tracking.

Through Vital Signs, an analog or digital alar

can be recorded. Steve Rhoades, of MMS, wrote 

code that links the Vitals Signs data and GPS l

and stores this data in an ASCII log file. SRL re

ers installed the equipment in a Caterpillar 7

truck. The result was a working prototype. Figur

2 show the instrument installation in the truck.

Discussion

From 8:30 pm on Sept. 14, 1998 until 6:50 

Sept. 15 1998, 899 jolts above a threshold of 2 g (1 

acceleration of gravity. It is either 9.81 m/s2

 or 

s2

.) were measured on the test truck. Some sec

the haulage road produced most of the event

20-22 20 8/2/00, 8:22 AM
MINING ENGINEERING ■ AUGUST 

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 has many uses. For example, it 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. 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 could be assumed 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 a high level, beyond

what normal operation should produce. Therefore, when an event is

produced, it is rare and more attention is paid to finding out its cause.

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 a

truck bed.

A pertinent question concerns

how this data would affect production. Would it cause drivers to slow

down or act tentatively? The key is

how the data is managed. Future

research will focus 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. The AMP

shock recorder operates on batteries and has built-in data storage.

The next generation prototype is

simplified and taps into the truck’s

system for electricity. It consists of

an analog, triaxial accelerometer

FIG. 3.

GPS data points for acceleration events (Frankel,

Spokane Research Laboratory).

Table 1

Specifications of the AMP recorder.

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

Accuracy of acceleration Better than 4% full-scale over temper

Accuracy of peak Better than 5% full-scale over temper

Pretrigger 1 sample

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22 AUGUST 2000 ■ MINING ENGINEERING

signal when a preset thre

exceeded.The specification

AMP recorder used are g

Table 1.

Conclusions

A data collection syst

ties acceleration and GPS l

data has been successfully 

strated at a cooperating min

riety of applications are p

Using plotting software, the 

reviewing the data produced 

the acceleration history of th

much like an infrared cam

display the thermal signatu

moving object.

Sophisticated hardwa

software monitors very low-

celerations and increases fun

ity. Severe jolts can be monit

using inexpensive hardwa

software. ■

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