This paper describes the design and testing of a wireless sensor network based on the SmartBrick, a low-power
SHM device developed by the authors. The SmartBrick serves as the base station for the network, which utilizes
additional sensor nodes to periodically evaluate the condition of the structure. Each node measures vibration,
tilt, humidity, and strain, and is designed for easy interfacing of virtually any other analog or digital sensor. The
sensor nodes use Zigbee to transmit their data to the base station, which in turn uses the GSM cellular phone
network to provide long-range communication and support for remote control.
The system has been designed from the outset to minimize power consumption, and is projected to operate
autonomously for up to four years without any on-site maintenance, due largely to the minimal power consumption
and rugged design. Remote calibration over the GSM network further increases the autonomy of the system.
Most importantly, it can perform all requisite actions with no cables for power or communication. The focus of
this paper is the addition of short-range wireless communication over Zigbee. This allows a network of several
devices to be used to monitor larger structures, such as multi-span bridges. Results of laboratory testing are
included and discussed in detail, demonstrating the unique capabilities of the proposed SHM system.
This paper describes an autonomous wireless system that generates road safety alerts, in the form of SMS and
email messages, and sends them to motorists subscribed to the service. Drivers who regularly traverse a particular
route are the main beneficiaries of the proposed system, which is intended for sparsely populated rural
areas, where information available to drivers about road safety, especially bridge conditions, is very limited. At
the heart of this system is the SmartBrick, a wireless system for remote structural health monitoring that has
been presented in our previous work. Sensors on the SmartBrick network regularly collect data on water level,
temperature, strain, and other parameters important to safety of a bridge. This information is stored on the
device, and reported to a remote server over the GSM cellular infrastructure. The system generates alerts indicating
hazardous road conditions when the data exceeds thresholds that can be remotely changed. The remote
server and any number of designated authorities can be notified by email, FTP, and SMS. Drivers can view road
conditions and subscribe to SMS and/or email alerts through a web page. The subscription-only form of alert
generation has been deliberately selected to mitigate privacy concerns. The proposed system can significantly
increase the safety of travel through rural areas. Real-time availability of information to transportation authorities
and law enforcement officials facilitates early or proactive reaction to road hazards. Direct notification of
drivers further increases the utility of the system in increasing the safety of the traveling public.
Proc. SPIE. 6932, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2008
KEYWORDS: Environmental monitoring, Sensors, Computing systems, Telecommunications, Structural health monitoring, Bridges, Embedded systems, Data communications, Floods, Global system for mobile communications
This paper describes an autonomous embedded system for remote monitoring of bridges. Salient features of the
system include ultra-low power consumption, wireless communication of data and alerts, and incorporation of
embedded sensors that monitor various indicators of the structural health of a bridge, while capturing the state
of its surrounding environment. Examples include water level, temperature, vibration, and acoustic emissions.
Ease of installation, physical robustness, remote maintenance and calibration, and autonomous data communication
make the device a self-contained solution for remote monitoring of structural health. The system
addresses shortcomings present in centralized structural health monitoring systems, particularly their reliance
on a laptop or handheld computer. The system has been field-tested to verify the accuracy of the collected data
and dependability of communication. The sheer volume of data collected, and the regularity of its collection can
enable accurate and precise assessment of the health of a bridge, guiding maintenance efforts and providing early
warning of potentially dangerous events. In this paper, we present a detailed breakdown of the system's power
requirements and the results of the initial field test.