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that determines a user's location continuously with a high degree of accuracy. It is a
light weight mobile, flexible and easy to use tracking device that can be used to help
locate mobile users in dynamically changing environments. The ITS can be
tremendously useful for inspectors, emergency response crews, military personnel,
and so on.
6.6 Summary and conclusions
The authors have studied several tracking technologies and have designed methods
and algorithms to track mobile users in congested environments, such as those
found on construction sites. The research described presented the GPS technology
and compared three different wireless technologies (WLAN, UWB, and Indoor
GPS) that can be used for tracking mobile users' position on outdoor and indoor
construction sites. As for tracking users' head orientation, a magnetic tracker was
adopted for both outdoor and indoor use. The decision on using one indoor
positioning technology over another should be based on important technical
criteria (e.g. calibration, line of sight, etc.) in addition to other logistic issues,
such as availability, the prevailing legal situation (e.g. permitted bandwidth), and
the associated implementation costs. However, based on the circumstances
expected to be encountered in the intended deployment environment (i.e. indoor
construction sites), the Indoor GPS positioning technology, coupled with the
magnetic orientation tracker, was found to offer the most promise for indoor user
tracking due to the low level of uncertainty in the reported user position (1-2 cm)
compared to that of WLAN (1.5-2 m) and UWB (10-50 cm).
The authors have also successfully designed and implemented an Integrated
Tracking System (ITS) that integrated RTK-GPS and inertial navigation (PDR)
positioning systems to continuously and accurately track the position of a mobile
user in order to help determine the user's spatial context. The ITS jumps in the
sustainability test walk are reflective of the average jump of several complex walks
with similar duration, indicating that the ITS is sustainable. The ITS's accuracy and
range in an indoor environment is within the similar range as WLAN positioning
systems. As the ITS incorporates elements of RTK-GPS tracking in an outdoor
environment, the accuracy and range of the ITS in an outdoor environment is
reflective of the same. Although the main focus of this chapter was on applying
tracking technologies to construction sites and civil engineering environments,
most of the findings of this research are generic and widely applicable to other fields
of science and engineering where context-aware and pervasive computing applica-
tions are implemented to deliver information efficiently.
Acknowledgments
The presented work is partially supported by the U.S. National Science Foundation
(NSF) through grant CMMI-0927475. The authors gratefully acknowledge NSF's
support. The authors would also like to thank PhD students Sanat Talmaki, Chunxia
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