Civil Engineering Reference
In-Depth Information
Designers need to carefully choose or design the hardware (including appropriate
processor board, sensor board, wireless communication module) and software
(including system software, if necessary, and application software) that will satisfy
the requirements. However, SHM application programmers, particularly civil
engineers, are generally not familiar with the operating system of WSN and
are unwilling to be exposed to the intricacies of WSNs, such as wireless commu-
nication and energy management, and so on. They wish to be only involved in
the development of application software. Therefore, middleware framework
which is able to provide programming abstractions is quite important. With
the help of the middleware, SHM application programmers can focus on the
SHM application logic without caring too much about the lower level implemen-
tation details.
However, developing middleware framework for a WSN-based SHM system is
not a trivial task. The main difficulty comes from the diversity of SHM applications.
Different SHM applications have different requirements in terms of sampling
frequency, communication range, synchronization accuracy, data delivery reliabil-
ity, detection accuracy and energy strategy, and so on. A versatile middleware
framework for WSN-based SHM should provide reusable services (e.g., synchro-
nized sensing, reliable data delivery) and also should be able to be configured or be
self-adaptive. Also, the way that different types of services are delivered, such as
query based, event triggered or pub/sub based, should be carefully considered in the
middleware framework.
To design a versatile middleware framework, some common services that most
of the SHM applications are required must firstly be identified. Fig. 11.5 lists the
common services required by most of the SHM applications are listed in
Figure 11.5. These services include:
Figure 11.5 Common services required by SHM applications
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