2.2.1. System architecture
The PCMS consists of two major parts (see Fig. 1) – the real-time
location system (RTLS) and the Virtual Construction Simulation
System (VCS).
2.2.1.1. Real-time location system (RTLS). The RTLS contains (1) a
real-time location network and (2) a real-time location engine.
Adopting real-time location technology in a dense and cluttered
construction site rather than a global positioning system (GPS)
(Modsching et al., 2006; Riaz et al., 2006), ultra-sonic and infrared
system (Lee et al., 2009), passive radio frequency identification system
(RFID) (Razavi and Moselhi, 2012), ultra-wideband system
(UWB) (Hallowell et al.; Carbonari et al., 2011), or a chirp spread
spectrum (CSS) is a wise choice because as a wireless network
technology, it uses the Institute of Electrical and Electronics Engineers
(IEEE) 802.15.4a in a wireless personal area network (WPAN)
and a time of arrival (TOA) as a location method (Kim et al., 2007;
Lee et al., 2011). Accordingly, it presents with an average error of
one meter—a relatively accurate result in comparison with previous
work.
The location engine finds the coordinates of the tags using trilateration
based on the three distance values while data are sent
to the application server through the location network. The RTLS
has three functions, to (1) manage the location network, (2) calculate
the tag locations and (3) relay danger alarm signals to specific
tags through the location network.