Page 137 - Advances In Productive, Safe, and Responsible Coal Mining

Communication and tracking 8

system performance

Steven J. Schafrik
University of Kentucky, Lexington, KY, United States

8.1 Introduction

Not long ago, most underground mines had limited or no tracking or wireless com-
munications systems in place. Mine operators were only aware of the names of the
individuals that were checked-in but had little knowledge of each individual’s location
and no real-time information. After several coal mine disasters, the United States (US)
Congress passed the Mine Improvement and New Emergency Response (MINER) Act
in 2006. Among other changes, the MINER Act amended existing laws and mandated
that above-ground personnel be able to determine the location of all underground per-
sonnel at any given point in time. US coal mines had three years to comply and get
wireless tracking systems in place.
A number of manufacturers developed and installed systems that allow for both
tracking underground personnel and equipment as well as two-way communication
between the surface and miners underground. Although tracking and communications
may seem unrelated, current systems combine both, since the underground location of
personnel needs to be communicated to the surface in real time. For tracking systems,
accuracy is the primary design constraint. According to guidelines, the location of an
individual should be known with an accuracy of 2000ft ( 660m) when not in an
active mining section or near strategic areas, whereas in active mining sections or stra-
tegic areas, the miners’ locations should be known within 200ft (66m).
This chapter covers the method of taking a mine map with locations for a mesh-based
tracking and communication system and predicting tracking system performance.

8.2 Measures of tracking system performance

A set of metric values describe the performance of a tracking system based on the
accuracy of position calculations across a spacial area over time. The purpose of these
metrics is to provide a basic set of values that can be calculated simply and are inde-
pendent of the technology used in the tracking system. They treat the tracking system
as a black-box calculator and are only concerned with the actual location of a tracked
device and the tracking system’s calculation of the location of the tracked device. The
tracked device’s actual location is expected to have very little error relative to the
tracking system and is the definition of the ground truth position (GTP) or the ground
truth position estimate (GTPE), used interchangeably. The tracking system calculates
Advances in Productive, Safe, and Responsible Coal Mining. https://doi.org/10.1016/B978-0-08-101288-8.00004-3
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